chapter 21 Anticholinergic Drugs Objectives AFTER STUDYING THIS CHAPTER, THE STUDENT WILL BE ABLE TO: 1. List characteristics of anticholinergic drugs in terms of effects on body tissues, indications for use, nursing process implications, observation of client response, and teaching clients. 2. Discuss atropine as the prototype of anticholinergic drugs. 3. Discuss clinical disorders/symptoms for which anticholinergic drugs are used. 4. Describe the mechanism by which atropine relieves bradycardia. 5. Review anticholinergic effects of antipsychotics, tricyclic antidepressants, and antihistamines. 6. Discuss principles of therapy and nursing process for using anticholinergic drugs in special populations. 7. Describe the signs and symptoms of atropine or anticholinergic drug overdose and its treatment. 8. Teach clients about the safe, effective use of anticholinergic drugs. Critical Thinking Scenario George Wilson, 76 years of age, has been treated for depression with amitriptyline (Elavil) for 5 years. He is admitted to the hospital for elective surgery, after which he becomes acutely confused. The physician prescribes haloperidol (Haldol) PRN to control severe agitation. You note in the drug reference text that both these medications have anticholinergic side effects. Reflect on: Important assessments to detect anticholinergic effects. How anticholinergic side effects can be especially significant for the elderly. Developing a plan to minimize or manage anticholinergic effects for this client. DESCRIPTION Anticholinergic drugs, also called cholinergic blocking and parasympatholytic agents, block the action of acetylcholine on the parasympathetic nervous system (PNS). Most anticholinergic drugs interact with muscarinic cholinergic receptors in the brain, secretory glands, heart, and smooth muscle and are also called antimuscarinic agents. A few anticholinergic drugs, when given at high doses, are also able to block nicotinic receptors in autonomic ganglia and skeletal muscles. Glycopyrrolate (Robinul) is an example of such a medication. The prototype anticholinergic drug is atropine, and this drug class includes belladonna alkaloids, their derivatives, and many synthetic substitutes. Most anticholinergic medications are either tertiary amines or quaternary amines in their chemical structure. Tertiary amines are uncharged lipid-soluble molecules. Atropine and scopolamine are tertiary amines and therefore are able to 308 cross cell membranes readily. They are well absorbed from the gastrointestinal (GI) tract and conjunctiva and they cross the blood–brain barrier. Tertiary amines are excreted in the urine. Some belladonna derivatives and synthetic anticholinergics are quaternary amines. These drugs carry a positive charge and are lipid insoluble. Consequently, they do not readily cross cell membranes. They are poorly absorbed from the GI tract and do not cross the blood–brain barrier. Quaternary amines are excreted largely in the feces. Table 21–1 lists common tertiary amine and quaternary amine anticholinergic drugs. Mechanism of Action and Effects These drugs act by occupying receptor sites at parasympathetic nerve endings, thereby leaving fewer receptor sites free to respond to acetylcholine (Fig. 21–1). Parasympathetic response is absent or decreased, depending on the number of CHAPTER 21 ANTICHOLINERGIC DRUGS TABLE 21–1 Common Tertiary Amine and Quaternary Amine Anticholinergic Drugs Tertiary Amines Quarternary Amines Atropine Benztropine (Cogentin) Biperiden (Akineton) Dicyclomine hydrochloride (Bentyl) Flavoxate (Urispas) l-Hyoscyamine (Anaspaz) Oxybutynin (Ditropan) Procyclidine (Kemadrin) Scopolamine Tolterodine (Detrol and Detrol LA) Trihexyphenidyl (Trihexy) Glycopyrrolate (Robinul) Ipratropium (Atrovent) Mepenzolate (Cantil) Methscopolamine (Pamine) Propantheline bromide (Pro-Banthine) receptors blocked by anticholinergic drugs and the underlying degree of parasympathetic activity. Since cholinergic muscarinic receptors are widely distributed in the body, anticholinergic drugs produce effects in a variety of locations, including the central nervous system, heart, smooth muscle, glands, and the eye. Specific effects on body tissues and organs include: 1. Central nervous system (CNS) stimulation followed by depression, which may result in coma and death. This is most likely to occur with large doses of anticholinergic drugs that cross the blood–brain barrier (atropine, scopolamine, and antiparkinson agents). 2. Decreased cardiovascular response to parasympathetic (vagal) stimulation that slows heart rate. Atropine is the anticholinergic drug most often used for its cardiovascular effects. According to Advanced Cardiac Life Support (ACLS) protocol (2000), atropine is the Nerve ending Presynaptic vesicles containing acetylcholine Acetylcholine Anticholinergic drug Muscarinic receptor Effector target organ Figure 21–1 Mechanism of action of anticholinergic drugs. Anticholinergic (antimuscarinic) blocking agents prevent acetylcholine from interacting with muscarinic receptors on target effector organs, thus blocking or decreasing a parasympathetic response in these organs. 309 drug of choice to treat symptomatic sinus bradycardia. Low doses (<0.5 mg) may produce a slight and temporary decrease in heart rate; however, moderate to large doses (0.5 to 1 mg) increase heart rate by blocking parasympathetic vagal stimulation. Although the increase in heart rate may be therapeutic in bradycardia, it can be an adverse effect in patients with other types of heart disease because atropine increases the myocardial oxygen demand. Atropine usually has little or no effect on blood pressure. Large doses cause facial flushing because of dilation of blood vessels in the neck. 3. Bronchodilation and decreased respiratory tract secretions. Bronchodilating effects result from blocking the bronchoconstrictive effects of acetylcholine. When anticholinergic drugs are given systemically, respiratory secretions decrease and may become viscous, resulting in mucous plugging of small respiratory passages. Administering the medications by inhalation decreases this effect while preserving the beneficial bronchodilation effect. 4. Antispasmodic effects in the GI tract due to decreased muscle tone and motility. The drugs have little inhibitory effect on gastric acid secretion with usual doses and insignificant effects on pancreatic and intestinal secretions. 5. Mydriasis and cycloplegia in the eye. Normally, anticholinergics do not change intraocular pressure, but with narrow-angle glaucoma, they may increase intraocular pressure and precipitate an episode of acute glaucoma. When the pupil is fully dilated, photophobia may be bothersome, and reflexes to light and accommodation may disappear. 6. Miscellaneous effects include decreased secretions from salivary and sweat glands; relaxation of ureters, urinary bladder, and the detrusor muscle; and relaxation of smooth muscle in the gallbladder and bile ducts. The clinical usefulness of anticholinergic drugs is limited by their widespread effects. Consequently, several synthetic drugs have been developed in an effort to increase selectivity of action on particular body tissues, especially to retain the antispasmodic and antisecretory effects of atropine while eliminating its adverse effects. This effort has been less than successful—all the synthetic drugs produce atropine-like adverse effects when given in sufficient dosage. One group of synthetic drugs is used for antispasmodic effects in GI disorders. Another group of synthetic drugs includes centrally active anticholinergics used in the treatment of Parkinson’s disease (see Chap. 12). They balance the relative cholinergic dominance that causes the movement disorders associated with parkinsonism. Indications for Use Anticholinergic drugs are used for disorders in many body systems. Clinical indications for use of anticholinergic drugs include GI, genitourinary, ophthalmic and respiratory dis- 310 SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM orders, bradycardia, and Parkinson’s disease. They also are used before surgery and bronchoscopy. Drugs at a Glance: Selected Anticholinergic Drugs describes the therapeutic use, dosage and route of administration of selected anticholinergic medications. • GI disorders in which anticholinergics have been used include peptic ulcer disease, gastritis, pylorospasm, diverticulitis, ileitis, and ulcerative colitis. These conditions are often characterized by excessive gastric acid and abdominal pain because of increased motility and spasm of GI smooth muscle. In peptic ulcer disease, more effective drugs have been developed, and anticholinergics are rarely used. The drugs are weak inhibitors of gastric acid secretion even in maximal doses (which usually produce intolerable adverse effects). Although they do not heal peptic ulcers, they may relieve abdominal pain by relaxing GI smooth muscle. Anticholinergics may be helpful in treating irritable colon or colitis, but they may be contraindicated in chronic inflammatory disorders (eg, diverticulitis, ulcerative colitis) or acute intestinal infections (eg, bacterial, viral, amebic). Other drugs are used to decrease diarrhea and intestinal motility in these conditions. • In genitourinary disorders, anticholinergic drugs may be given for their antispasmodic effects on smooth muscle to relieve the symptoms of urinary incontinence and frequency that accompany an overactive bladder. In infections such as cystitis, urethritis, and prostatitis, the drugs decrease the frequency and pain of urination. The drugs are also given to increase bladder capacity in enuresis, paraplegia, or neurogenic bladder. • In ophthalmology, anticholinergic drugs are applied topically for mydriatic and cycloplegic effects to aid examination or surgery. They are also used to treat some inflammatory disorders. Anticholinergic preparations used in ophthalmology are discussed further in Chapter 65. • In respiratory disorders characterized by bronchoconstriction (ie, asthma, chronic bronchitis), ipratropium (Atrovent) may be given by inhalation for bronchodilating effects (see Chap. 47). • In cardiology, atropine may be given to increase heart rate in bradycardia and heart block characterized by hypotension and shock. • In Parkinson’s disease, anticholinergic drugs are given for their central effects in decreasing salivation, spasticity, and tremors. They are used mainly in clients who have minimal symptoms, who do not respond to levodopa, or who cannot tolerate levodopa because of adverse reactions or contraindications. An additional use of anticholinergic drugs is to relieve Parkinson-like symptoms that occur with older antipsychotic drugs. • Before surgery, anticholinergics are given to prevent vagal stimulation and potential bradycardia, hypotension, and cardiac arrest. They are also given to reduce respiratory tract secretions, especially in head and neck surgery and bronchoscopy. Contraindications to Use Contraindications to the use of anticholinergic drugs include any condition characterized by symptoms that would be aggravated by the drugs. Some of these are prostatic hypertrophy, myasthenia gravis, hyperthyroidism, glaucoma, tachyarrhythmias, myocardial infarction, and heart failure unless bradycardia is present. They should not be given in hiatal hernia or other conditions contributing to reflux esophagitis because the drugs delay gastric emptying, relax the cardioesophageal sphincter, and increase esophageal reflux. INDIVIDUAL ANTICHOLINERGIC DRUGS Belladonna Alkaloids and Derivatives Atropine, the prototype of anticholinergic drugs, produces the same effects, has the same clinical indications for use, and has the same contraindications as those described earlier. In addition, it is used as an antidote for an overdose of cholinergic drugs and exposure to insecticides that have cholinergic effects. Atropine is a naturally occurring belladonna alkaloid that can be extracted from the belladonna plant or prepared synthetically. It is usually prepared as atropine sulfate, a salt that is very soluble in water. It is well absorbed from the GI tract and distributed throughout the body. It crosses the blood–brain barrier to enter the CNS, where large doses produce stimulant effects and toxic doses produce depressant effects. Atropine is also absorbed systemically when applied locally to mucous membranes. The drug is rapidly excreted in the urine. Pharmacologic effects are of short duration except for ocular effects, which may last for several days. Belladonna tincture is a mixture of alkaloids in an aqueousalcohol solution. It is most often used in GI disorders for antispasmodic effect. It is an ingredient in several drug mixtures. Homatropine hydrobromide (Homapin) is a semisynthetic derivative of atropine used as eye drops to produce mydriasis and cycloplegia. Homatropine may be preferable to atropine because ocular effects do not last as long. Hyoscyamine (Anaspaz) is a belladonna alkaloid used in GI and genitourinary disorders characterized by spasm, increased secretion, and increased motility. It has the same effects as other atropine-like drugs. Ipratropium (Atrovent) is an anticholinergic drug chemically related to atropine. When given as a nasal spray, it is useful in treating rhinorrhea due to allergy or the common cold. When given as an inhalation treatment or aerosol to patients with chronic obstructive pulmonary disease (COPD), it is beneficial as a bronchodilator. An advantage of administration of anticholinergic drugs by the respiratory route over systemic administration is less thickening of respiratory secretions and reduced incidence of mucus-plugged airways. Scopolamine is similar to atropine in uses, adverse effects, and peripheral effects but different in central effects. CHAPTER 21 ANTICHOLINERGIC DRUGS 311 Drugs at a Glance: Selected Anticholinergic Drugs Routes and Dosage Ranges Generic/Trade Name Use Adults Children Belladonna Alkaloids and Derivatives Atropine Systemic use PO, IM, SC, IV 0.4–0.6 mg Surgery IM, SC, or IV 0.4–0.6 mg prior to induction. Use 0.4-mg dose with cyclopropane anesthesia. IV 0.4–1 mg (up to 2 mg) q1–2h PRN. IV titrate large doses of 2–3 mg as needed until signs of atropine toxicity appear and cholinergic crisis is controlled. For refraction: Instill 1–2 drops of 1% solution into eye(s) 1 h before refraction. For uveitis: Instill 1–2 drops of 1% solution into eye(s) qid. For refraction: Instill 1–2 drops of 2% solution or 1 drop 5% solution into eye before procedure. May repeat at 5–10 min intervals as needed. For uveitis: Instill 1–2 drops of 2% or 5% solution bid to tid or every 3–4 h as needed. PO, SL 0.125–0.25 mg tid or qid, ac and hs. PO (timedrelease formula): 0.375–0.75 q12h. IM, IV, SC: 0.25–0.5 mg q6h. 2 puffs (36 mcg) of aerosol qid. Additional inhalations may be needed. Do not exceed 12 puffs/24h. Solution for inhalation: 500 mcg, tid–qid. 2 sprays/nostril of 0.03% spray bid–tid. 2 sprays/nostril of 0.06% spray tid–qid. PO 0.4–0.8 mg qd. SC, IM 0.32–0.65 mg IV 0.32–0.65 mg diluted in sterile water for injection. Transdermal: Apply disc 4 h before antiemetic effect is needed. Replace q 3 days. For refraction: Instill 1–2 drops into eye 1 h before refracting. For uveitis: Instill 1–2 drops into eye(s) up to tid. PO, IM, SC, IV: 7–16 lbs: 0.1 mg 16–24 lbs: 0.15 mg 24–40 lbs: 0.2 mg 40–65 lbs: 0.3 mg 65–90 lbs: 0.4 mg >90 lbs 0.4–0.6 mg 0.1 mg (newborn) to 0.6 mg (12 y) given SC 30 min prior to surgery. Bradyarrythmias Antidote for cholinergic poisoning Ophthalmic atropine (Isopto-Atropine) Mydriatic/cycloplegia/ inflammation of uveal tract Homatropine (Homapin) Mydriatic/cycloplegia/ inflammation of uveal tract Hyoscyamine (Anaspaz) Antispasmodic Antisecretory for gastrointestinal (GI) and genitourinary (GU) disorders Ipratropium (Atrovent) Bronchodilation Nasal spray for rhinorrhea Scopolamine Systemic use Antiemetic Mydriatic/cycloplegia/ inflammation of uveal tract For refraction: Instill 1–2 drops of 0.5% solution bid for 1–3 days before procedure. For refraction: Instill 1 drop of 2% solution into eye before procedure. May repeat q 10 min as needed. For uveitis: Instill 1 drop of 2% solution bid to tid. Children 2–10 y: PO 0.062–0.125 mg q 6–8h. Children <2 y: half of the previous dose. 2 sprays/nostril of 0.03% spray bid–tid. Not approved for PO use <6 y. Parenteral: 0.006 mg/kg. Maximum dose: 0.3 mg. Not approved in children. Same as adult dose (continued ) 312 SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM Drugs at a Glance: Selected Anticholinergic Drugs (continued ) Routes and Dosage Ranges Generic/Trade Name Use Antisecretory/Antispasmodic Anticholinergics for GI Disorders Dicyclomine hydrochloride (Bentyl) Antisecretory/antispasmodic Glycopyrrolate (Robinul) Antisecretory/antispasmodic Preanesthetic Mepenzolate (Cantil) Methscopolamine (Pamine) Propantheline bromide (Pro-Banthine) Antisecretory/antispasmodic Antisecretory/antispasmodic Antisecretory/antispasmodic Anticholinergics Used in Parkinson’s Disease Benztropine (Cogentin) Parkinsonism Drug-induced extrapyramidal symptoms Biperiden (Akineton) Parkinsonism Drug-induced extrapyramidal symptoms Procyclidine (Kemadrin) Parkinsonism Drug-induced extrapyramidal symptoms Trihexyphenidyl (Trihexy) Parkinsonism Drug-induced extrapyramidal symptoms Urinary Antispasmodics Flavoxate (Urispas) Oxybutynin (Ditropan and Ditropan XL) Tolterodine (Detrol and Detrol LA) ac, before meals; hs, bedtime; pc, after meals. Adults PO 20–40 mg ac & hs IM 20 mg ac & hs PO 1–2 mg bid–tid IM, IV 0.1–0.2 mg IM 0.004 mg/kg 30–60 min before anesthesia PO 25–50 mg qid ac & hs PO 2.5–5 mg 30 min ac & hs PO 7.5–15 mg 30 min ac & hs Children < 12 y: not recommended <2 y: 0.004 mg/lb IM 30–60 min before anesthesia. 2–12 y: 0.002–0.004 mg/lb IM 30–60 min before anesthesia. 200 mcg/kg ac & hs PO, IM, IV 0.5–1 mg hs. May increase up to 6 mg given hs or in 2–4 divided doses. For acute dystonia: IM, IV 1–2 mg. May repeat if needed. For prevention: PO 1–2 mg. PO 2 mg tid–qid. Maximum dose 16 mg/day. PO 2 mg tid–qid IM, IV 2 mg. Repeat q12h until symptoms are resolved. Do not give more than 4 doses/24h PO 2.5 mg tid pc. May increase to 5 mg tid. PO 2.5 mg tid. Increase by 2.5-mg increments until symptoms are resolved. Usual maximum dose 10–20 mg/d. PO 1–2 mg. Increase by 2 mg increments at 3–5-d intervals until a total of 6–10 mg is given qd in divided doses 3–4 times/d at mealtimes and bedtimes. PO 1 mg initially. Increase as needed to control symptoms. PO 100–200 mg tid–qid. Reduce when symptoms improve. PO 5 mg bid or tid. Maximum dose 5 mg qid. Extended-release 5 mg PO qd up to 30 mg/d. PO 2 mg bid. May decrease to 1 mg when symptoms improve. Reduce doses to 1 mg PO bid in presence of hepatic impairment. <12 y: safety and efficacy not established >5 y: 5 mg PO bid. Maximum dose 5 mg tid. Safety and efficacy not established. CHAPTER 21 ANTICHOLINERGIC DRUGS When given parenterally, scopolamine depresses the CNS and causes amnesia, drowsiness, euphoria, relaxation, and sleep. Effects of scopolamine appear more quickly and disappear more readily than those of atropine. Scopolamine also is used in motion sickness. It is available as oral tablets and as a transdermal adhesive disc that is placed behind the ear. The disc (Transderm-V) protects against motion sickness for 72 hours. Centrally Acting Anticholinergics Used in Parkinson’s Disease Older anticholinergic drugs such as atropine are rarely used to treat Parkinson’s disease because of their undesirable peripheral effects (eg, dry mouth, blurred vision, photophobia, constipation, urinary retention, and tachycardia). Newer, centrally acting synthetic anticholinergic drugs are more selective for muscarinic receptors in the CNS and are designed to produce fewer side effects. Trihexyphenidyl (Trihexy) is used in the treatment of parkinsonism and extrapyramidal reactions caused by some antipsychotic drugs. Trihexyphenidyl relieves smooth muscle spasm by a direct action on the muscle and by inhibiting the PNS. The drug supposedly has fewer side effects than atropine, but approximately half the recipients report mouth dryness, blurring of vision, and other side effects common to anticholinergic drugs. Trihexyphenidyl requires the same precautions as other anticholinergic drugs and is contraindicated in glaucoma. Biperiden (Akineton) and procyclidine (Kemadrin) are chemical derivatives of trihexyphenidyl and have similar actions. Benztropine (Cogentin) is a synthetic drug with both anticholinergic and antihistaminic effects. Its anticholinergic activity approximates that of atropine. A major clinical use is to treat acute dystonic reactions caused by antipsychotic drugs and to prevent their recurrence in clients receiving long-term antipsychotic drug therapy. It also may be given in small doses to supplement other antiparkinson drugs. In full dosage, adverse reactions are common. Urinary Antispasmodics Flavoxate (Urispas) was developed specifically to counteract spasm in smooth muscle tissue of the urinary tract. It has anticholinergic, local anesthetic, and analgesic effects. Thus, the drug relieves dysuria, urgency, frequency, and pain with genitourinary infections, such as cystitis and prostatitis. 313 How Can You Avoid This Medication Error? Sam Miller is admitted for elective surgery. He has a history of heart disease, glaucoma, and benign prostatic hyperplasia (BPH). After surgery, a scopolamine patch is prescribed to control nausea. You administer the patch, as ordered, placing it on his chest in a nonhairy area. Oxybutynin (Ditropan and Ditropan XL) has direct antispasmodic effects on smooth muscle and anticholinergic effects. It increases bladder capacity and decreases frequency of voiding in clients with neurogenic bladder. Oxybutynin is now available in an extended-release form for once a day dosing. Tolterodine (Detrol and Detrol LA) is a competitive antimuscarinic, anticholinergic agent that inhibits bladder contraction, decreases detrusor muscle pressure, and delays the urge to void. It is used to treat urinary frequency, urgency, and urge incontinence. Tolterodine is more selective for muscarinic receptors in the urinary bladder than other areas of the body, such as the salivary glands, and therefore anticholinergic side effects are less marked. Reduced doses (of 1 mg) are recommended for those with hepatic dysfunction. Tolterodine is also available in an extended-release form. Nursing Process Assessment • Assess the client’s condition in relation to disorders for which anticholinergic drugs are used (ie, check for bradycardia or heart block, diarrhea, dysuria, abdominal pain, and other disorders). If the client reports or medical records indicate a specific disorder, assess for signs and symptoms of that disorder (eg, Parkinson’s disease). • Assess for disorders in which anticholinergic drugs are contraindicated (eg, glaucoma, prostatic hypertrophy, reflux esophagitis, myasthenia gravis, hyperthyroidism). • Assess use of other drugs with anticholinergic effects, such as antihistamines (histamine-1 receptor antagonists [see Chap. 48]), antipsychotic agents, and tricyclic antidepressants. Nursing Diagnoses • Impaired Urinary Elimination: Decreased bladder tone and urine retention Nursing Notes: Apply Your Knowledge Scott Andrews is scheduled for a bronchoscopy. Before this procedure, you have been ordered to give him Valium and atropine. Explain the rationale of giving an anticholinergic agent as a preoperative medication. • Constipation related to slowed GI function • Disturbed Thought Processes: Confusion, disorientation, especially in older adults • Deficient Knowledge: Drug effects and accurate usage • Risk for Injury related to drug-induced blurred vision and photophobia • Risk for Noncompliance related to adverse drug effects • Risk for Altered Body Temperature: Hyperthermia 314 SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM Planning/Goals The client will: • Receive or self-administer the drugs correctly • Experience relief of symptoms for which anticholinergic drugs are given • Be assisted to avoid or cope with adverse drug effects on vision, thought processes, bowel and bladder elimination, and heat dissipation Interventions Use measures to decrease the need for anticholinergic drugs. For example, with peptic ulcer disease, teach the client to avoid factors known to increase gastric secretion and GI motility (alcohol; cigarette smoking; caffeine-containing beverages, such as coffee, tea, and cola drinks; ulcerogenic drugs, such as aspirin). Late evening snacks also should be avoided because increased gastric acid secretion occurs approximately 90 minutes after eating and may cause pain and awakening from sleep. Although milk was once considered an “ulcer food,” it contains protein and calcium, which promote acid secretion, and is a poor buffer of gastric acid. Thus, drinking large amounts of milk should be avoided. Evaluation • Interview and observe in relation to safe, accurate drug administration. • Interview and observe for relief of symptoms for which the drugs are given. • Interview and observe for adverse drug effects. PRINCIPLES OF THERAPY Gastrointestinal Disorders When anticholinergic drugs are given for GI disorders, larger doses may be given at bedtime to prevent pain and awakening during sleep. Parkinsonism When these drugs are used in parkinsonism, small doses are given initially and gradually increased. This regimen decreases adverse reactions. Extrapyramidal Reactions When used in drug-induced extrapyramidal reactions (parkinson-like symptoms), these drugs should be prescribed only if symptoms occur. They should not be used routinely to prevent extrapyramidal reactions because fewer than half the clients taking antipsychotic drugs experience such reactions. Most drug-induced reactions last approximately 3 months and do not recur if anticholinergic drugs are discontinued at that time. (An exception is tardive dyskinesia, which does not respond to anticholinergic drugs and may be aggravated by them.) Muscarinic Agonist Poisoning Atropine is the antidote for poisoning by muscarinic agonists such as certain species of mushrooms, cholinergic agonist drugs, cholinesterase inhibitor drugs, and insecticides containing organophosphates. Symptoms of muscarinic poisoning include salivation, lacrimation, visual disturbances, bronchospasm, diarrhea, bradycardia, and hypotension. Atropine blocks the poison from interacting with the muscarinic receptor, thus reversing the toxic effects. Use in Specific Conditions Asthma Renal or Biliary Colic Atropine is sometimes given with morphine or meperidine to relieve the severe pain of renal or biliary colic. It acts mainly to decrease the spasm-producing effects of the opioid analgesics. It has little antispasmodic effect on the involved muscles and is not used alone for this purpose. Oral anticholinergics are not used to treat asthma and other chronic obstructive pulmonary diseases because of their tendency to thicken secretions and form mucus plugs in airways. Ipratropium (Atrovent) may be given by inhalation to produce bronchodilation without thickening of respiratory secretions. Preoperative Use in Clients With Glaucoma Toxicity of Anticholinergics: Recognition and Management Glaucoma is usually listed as a contraindication to anticholinergic drugs because the drugs impair outflow of aqueous humor and may cause an acute attack of glaucoma (increased intraocular pressure). However, anticholinergic drugs can be given safely before surgery to clients with open-angle glaucoma (80% of clients with primary glaucoma) if they are receiving miotic drugs, such as pilocarpine. If anticholinergic preoperative medication is needed in clients predisposed to angle closure, the hazard of causing acute glaucoma can be minimized by also giving pilocarpine eye drops and acetazolamide (Diamox). Overdosage of atropine or other anticholinergic drugs produces the usual pharmacologic effects in a severe and exaggerated form. The anticholinergic overdose syndrome is characterized by hyperthermia; hot, dry, flushed skin; dry mouth; mydriasis; delirium; tachycardia; ileus; and urinary retention. Myoclonic movements and choreoathetosis may be seen. Seizures, coma, and respiratory arrest may also occur. Treatment involves use of activated charcoal to absorb ingested poison. Hemodialysis, hemoperfusion, peritoneal dialysis, and repeated doses of charcoal are not effective in removing anticholinergic agents. CHAPTER 21 ANTICHOLINERGIC DRUGS 315 CLIENT TEACHING GUIDELINES Anticholinergic Drugs General Considerations ✔ Do not take other drugs without the physician’s knowledge. In addition to some prescribed antiparkinson drugs, antidepressants, antihistamines, and antipsychotic drugs with anticholinergic properties, over-the-counter sleeping pills and antihistamines have anticholinergic effects. Taking any of these concurrently could cause overdosage or excessive anticholinergic effects. ✔ Use measures to minimize risks of heat exhaustion and heat stroke: ✔ Wear light, cool clothing in warm climates or environments. ✔ Maintain fluid and salt intake if not contraindicated. ✔ Limit exposure to direct sunlight. ✔ Limit physical activity. ✔ Take frequent cool baths. ✔ Ensure adequate ventilation, with fans or air conditioners if necessary. ✔ Avoid alcoholic beverages. ✔ Use sugarless chewing gum and hard candy, if not contraindicated, to relieve mouth dryness. ✔ Carry out good dental hygiene practices (eg, regular brushing of teeth) to prevent dental caries and loss of teeth that may result from drug-induced xerostomia (dry mouth from decreased saliva production). This is more likely to occur with long-term use of these drugs. Physostigmine salicylate (Antilirium), an acetylcholinesterase inhibitor, is a specific antidote. It is usually given intravenously (IV) at a slow rate of injection. Adult dosage is 2 mg (no more than 1 mg/minute); child dosage is 0.5 to 1 mg (no more than 0.5 mg/minute). Rapid administration may cause bradycardia, hypersalivation (with subsequent respiratory distress), and seizures. Repeated doses may be given if life-threatening dysrhythmias, convulsions, or coma occur. Diazepam (Valium) or a similar drug may be given for excessive CNS stimulation (delirium, excitement). Ice bags, cooling blankets, and tepid sponge baths may help reduce fever. Artificial ventilation and cardiopulmonary resuscitative measures are used if excessive depression of the CNS causes coma and respiratory failure. Infants, children, and the elderly are especially susceptible to the toxic effects of anticholinergic agents. ✔ To prevent injury due to blurring of vision or drowsiness, avoid potentially hazardous activities (eg, driving or operating machinery). ✔ To reduce sensitivity to light (photophobia), dark glasses can be worn outdoors in strong light. ✔ Contact lens wearers who experience dry eyes may need to use an ophthalmic lubricating solution. ✔ When using anticholinergic ophthalmic preparations, if eye pain occurs, stop using the medication and contact your physician or health care provider. This may be a warning sign of undiagnosed glaucoma. ✔ Notify your physician or health care provider if urinary retention or constipation occurs. ✔ Tell your physician or health care provider if you are pregnant or breast-feeding or allergic to sulfite preservatives or any other atropine compound. Self-Administration ✔ Take anticholinergic drugs for gastrointestinal disorders 30 minutes before meals and at bedtime. ✔ Safeguard anticholinergic medications from children because they are especially sensitive to atropine poisoning. ✔ To prevent constipation, use a diet high in fiber. Include whole grains, fruits, and vegetables in your daily menu. Also, drink 2 to 3 quarts of fluid a day and exercise regularly. spasmodics, flavoxate is not recommended for children younger than 12 years, oxybutynin is not recommended for children younger than 5 years of age, and the safety and efficacy of tolterodine are not established in children. The drugs cause the same adverse effects in children as in adults. However, they may be more severe because children are especially sensitive to the drugs. Facial flushing is common in children, and a skin rash may occur. Ophthalmic anticholinergic drugs are used for cycloplegia and mydriasis before eye examinations and surgical procedures (see Chap. 65). They should be used only with close medical supervision. Cyclopentolate (Cyclogyl) and tropicamide (Mydriacyl) have been associated with behavioral disturbances and psychotic reactions in children. Tropicamide also has been associated with cardiopulmonary collapse. Use in Older Adults Use in Children Systemic anticholinergics, including atropine, glycopyrrolate (Robinul), and scopolamine, are given to children of all ages for essentially the same effects as for adults. Most of the antisecretory, antispasmodic agents for gastrointestinal disorders are not recommended for children. With the urinary anti- Anticholinergic drugs are given for the same purposes as in younger adults. In addition to the primary anticholinergic drugs, many others that are commonly prescribed for older adults have high anticholinergic activity. These include many antihistamines (histamine-1 receptor antagonists), tricyclic antidepressants, and antipsychotic drugs. 316 SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM Older adults are especially likely to have significant adverse reactions because of slowed drug metabolism and the frequent presence of several disease processes. Some common adverse effects and suggestions for reducing their impact are: • Blurred vision. The client may need help with ambulation, especially with stairs or other potentially hazardous environments. Remove obstacles and hazards when possible. • Confusion. Provide whatever assistance is needed to prevent falls and other injuries. • Heat stroke. Help to avoid precipitating factors, such as strenuous activity and high environmental temperatures. • Constipation. Encourage or assist with an adequate intake of high-fiber foods and fluids and adequate exercise when feasible. • Urinary retention. Encourage adequate fluid intake and avoid high doses of the drugs. Men should be examined for prostatic hypertrophy. • Hallucinations and other psychotic symptoms. These are most likely to occur with the centrally active anticholinergics given for Parkinson’s disease or druginduced extrapyramidal effects, such as trihexyphenidyl or benztropine. Dosage of these drugs should be carefully regulated and supervised. such a medication. In the presence of liver impairment, dosages should be reduced and given less frequently. Use in Critical Illness Atropine is an important drug in the emergency drug box. According to ACLS guidelines, atropine is the first drug to be administered in the emergency treatment of bradyarrhythmias. Atropine 0.5 to 1 mg should be administered IV every 5 minutes and may be repeated up to 2 to 3 mg (0.03 to 0.04 mg/kg total dose). For clients with asystole, 1 mg of atropine is administered IV and repeated every 3 to 5 minutes if asystole persists, up to 0.04 mg/kg. Administration of atropine in doses less than 0.5 mg should be avoided because this may result in a paradoxical bradycardia. Atropine may be administered by endotracheal tube in clients without an intravenous access. The recommended dose is 2 to 3 mg diluted in 10 mL normal saline. Abuse of Anticholinergic Agents Anticholinergic drugs have potential intoxicating effects. Abuse of these drugs may produce euphoria, disorientation, hallucinations, and paranoia in addition to the classic anticholinergic adverse reactions. Use in Renal Impairment Anticholinergic agents that have a tertiary amine structure, such as atropine, are eliminated by a combination of hepatic metabolism and renal excretion. In the presence of renal impairment, they may accumulate and cause increased adverse effects. Quaternary amines are eliminated largely in the feces and are less affected by renal impairment. Use in Hepatic Impairment Because some anticholinergic drugs are metabolized by the liver, they may accumulate and cause adverse effects in the presence of hepatic impairment. Tolterodine is an example of Home Care Anticholinergic medications are commonly used in home care with children and adults. Children and older adults are probably most likely to experience adverse effects of these drugs and should be monitored carefully. With elderly clients, the home care nurse needs to assess medication regimens for combinations of drugs with anticholinergic effects, especially if mental confusion develops or worsens. The home care nurse may also need to teach elderly clients or caregivers that the drugs prevent sweating and heat loss and increase risks of heat stroke if precautions to avoid overheating are not taken. CHAPTER 21 ANTICHOLINERGIC DRUGS NURSING ACTIONS 317 Anticholinergic Drugs NURSING ACTIONS RATIONALE/EXPLANATION 1. Administer accurately a. For gastrointestinal disorders, give most oral anticholinergic drugs approximately 30 min before meals and at bedtime. To allow the drugs to reach peak antisecretory effects by the time ingested food is stimulating gastric acid secretion. Bedtime administration helps prevent awakening with abdominal pain. b. When given before surgery, parenteral preparations of atropine can be mixed in the same syringe with several other common preoperative medications, such as meperidine (Demerol), morphine, oxymorphone (Numorphan), and promethazine (Phenergan). The primary reason for mixing medications in the same syringe is to decrease the number of injections and thus decrease client discomfort. Note, however, that extra caution is required when mixing drugs to be sure that the dosage of each drug is accurate. Also, if any question exists regarding compatibility with another drug, it is safer not to mix the drugs, even if two or three injections are required. c. When applying topical atropine solutions or ointment to the eye, be sure to use the correct concentration and blot any excess from the inner canthus. Atropine ophthalmic preparations are available in several concentrations (usually 1%, 2%, and 3%). Excess medication should be removed so the drug will not enter the nasolacrimal (tear) ducts and be absorbed systemically through the mucous membrane of the nasopharynx or be carried to the throat and swallowed. d. If propantheline is to be given intravenously, dissolve the 30-mg dose of powder in no less than 10 mL of sterile water for injection. Parenteral administration is reserved for clients who cannot take the drug orally. e. Instruct clients to swallow oral propantheline tablets, not to chew them. The tablets have a hard sugar coating to mask the bitter taste of the drug. f. Parenteral glycopyrrolate can be given through the tubing of a running intravenous infusion of physiologic saline or lactated Ringer’s solution. g. Do not crush extended-release forms of anticholinergic drugs such as Detrol LA and Ditropan XL. 2. Observe for therapeutic effects Crushing long-acting medications may result in high blood levels of the medication and increased adverse effects. Therapeutic effects depend primarily on the reason for use. Thus, a therapeutic effect in one condition may be a side effect or an adverse reaction in another condition. a. When a drug is given for peptic ulcer disease or other gastrointestinal disorders, observe for decreased abdominal pain. Relief of abdominal pain is due to the smooth muscle relaxant or antispasmodic effect of the drug. b. When the drug is given for diagnosing or treating eye disorders, observe for pupil dilation (mydriasis) and blurring of vision (cycloplegia). Note that these ocular effects are side effects when the drugs are given for problems not related to the eyes. c. When the drug is given for symptomatic bradycardia, observe for increased pulse rate. These drugs increase heart rate by blocking action of the vagus nerve. d. When the drug is given for urinary tract disorders, such as cystitis or enuresis, observe for decreased frequency of urination. When the drug is given for renal colic due to stones, observe for decreased pain. Anticholinergic drugs decrease muscle tone and spasm in the smooth muscle of the ureters and urinary bladder. e. When the centrally acting anticholinergics are given for Parkinson’s disease, observe for decrease in tremor, salivation, and drooling. Decreased salivation is a therapeutic effect with parkinsonism but an adverse reaction in most other conditions. (continued ) 318 SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM NURSING ACTIONS RATIONALE/EXPLANATION 3. Observe for adverse effects These depend on reasons for use and are dose related. a. Tachycardia Tachycardia may occur with usual therapeutic doses because anticholinergic drugs block vagal action, which normally slows heart rate. Tachycardia is not likely to be serious except in clients with underlying heart disease. For example, in clients with angina pectoris, prolonged or severe tachycardia may increase myocardial ischemia to the point of causing an acute attack of angina (chest pain) or even myocardial infarction. In clients with congestive heart failure, severe or prolonged tachycardia can increase the workload of the heart to the point of causing acute heart failure or pulmonary edema. b. Excessive central nervous system (CNS) stimulation (tremor, restlessness, confusion, hallucinations, delirium) followed by excessive CNS depression (coma, respiratory depression) These effects are more likely to occur with large doses of atropine because atropine crosses the blood-brain barrier. Large doses of trihexyphenidyl (Trihexy) also may cause CNS stimulation. c. Sedation and amnesia with scopolamine or benztropine (Cogentin) This may be a therapeutic effect but becomes an adverse reaction if severe or if the drug is given for another purpose. Benztropine has anticholinergic and antihistaminic properties. Apparently, drowsiness and sedation are caused by the antihistaminic component. d. Constipation or paralytic ileus These effects are the result of decreased gastrointestinal motility and muscle tone. Constipation is more likely with large doses or parenteral administration. Paralytic ileus is not likely unless the drugs are given to clients who already have decreased gastrointestinal motility. e. Decreased oral and respiratory tract secretions, which cause mouth dryness and thick respiratory secretions Mouth dryness is more annoying than serious in most cases and is caused by decreased salivation. However, clients with chronic lung disease, who usually have excessive secretions, tend to retain them with the consequence of frequent respiratory tract infections. f. Urinary retention This reaction is caused by loss of bladder tone and is most likely to occur in elderly men with enlarged prostate glands. Thus, the drugs are usually contraindicated with prostatic hypertrophy. g. Hot, dry skin; fever; heat stroke These effects are due to decreased sweating and impairment of the normal heat loss mechanism. Fever may occur with any age group. Heat stroke is more likely to occur with cardiovascular disease, strenuous physical activity, and high environmental temperatures, especially in elderly people. h. Ocular effects-mydriasis, blurred vision, photophobia These are adverse effects when anticholinergic drugs are given for conditions not related to the eyes. 4. Observe for drug interactions a. Drugs that increase effects of anticholinergic drugs: Antihistamines, disopyramide, phenothiazines, thioxanthene agents, tricyclic antidepressants and amantadine These drugs have anticholinergic properties and produce additive anticholinergic effects. b. Drugs that decrease effects of anticholinergic drugs: Cholinergic drugs These drugs counteract the inhibition of gastrointestinal motility and tone induced by atropine. They are sometimes used in atropine overdose. CHAPTER 21 ANTICHOLINERGIC DRUGS Nursing Notes: Apply Your Knowledge Answer: Although anticholinergic medications are no longer used routinely as preoperative medication, they are still used in some preoperative situations when decreased secretions in the respiratory tract are important. Also, anticholinergic agents block excessive vagal stimulation by the parasympathetic nervous system, which can occur after administration of some anesthetics or muscle relaxants (eg, succinylcholine) or after manipulation of the pharynx or trachea. Vagal stimulation causes bradycardia and hypotension, and in severe cases can result in cardiac arrest. How Can You Avoid This Medication Error? Answer: To prevent possible complications, more information must be obtained from Mr. Miller before the scopolamine patch can be safely administered. If Mr. Miller has closed-angle glaucoma, administering an anticholinergic agent could result in a significant rise in intraocular pressure and visual impairment. If it cannot be determined whether Mr. Miller has open-angle or closed-angle glaucoma, the drug should be held. Anticholinergic medications should be used cautiously with clients who have BPH because these drugs can cause urinary retention. Anticholinergic medications increase heart rate, which may not be advisable for many clients with heart disease. Review and Application Exercises 1. How do anticholinergic drugs exert their therapeutic effects? 2. What are indications for use and contraindications for anticholinergic drugs? 3. What is the effect of anticholinergic drugs on heart rate, and what is the mechanism for this effect? 4. Under what circumstances is it desirable to administer atropine before surgery, and why? 5. What are adverse effects of anticholinergic drugs? 319 6. What treatment measures are indicated for a client with an overdose of a drug with anticholinergic effects? 7. Name two other commonly used drug groups that have anticholinergic effects. 8. What nursing observations and interventions are needed to increase client safety and comfort during anticholinergic drug therapy? SELECTED REFERENCES Brown, J. H. & Taylor, P. (2001). Muscarinic receptor agonists and antagonists. In J. G. Hardman & L. E. Limbird. (Eds.), Goodman & Gilman’s The pharmacological basis of therapeutics, 10th ed., pp. 155–173. New York: McGraw-Hill. Crabtree, B. L. & Polles, A. (1997). Substance-related disorders. In J. T. Dipiro, R. L. Talbert, G. C. Yee, G. R. Matzke, B. G. Wells, and L. M. Posey (Eds.), Pharmacotherapy: A pathophysiologic approach, 3rd ed., pp. 1345–1365. Stamford, CT: Appleton & Lange. Drug facts and comparisons. (Updated monthly). St. Louis: Facts and Comparisons. Hazinski, M. F., Cummins, R. O., & Field, J. M. (Eds.). (2000). Handbook of emergency cardiovascular care for health care providers. Dallas: American Heart Association. Jones, L. A. (1997). Pharmacotherapy of cardiopulmonary resuscitation. In J. T. Dipiro, R. L. Talbert, G. C. Yee, G. R. Matzke, B. G. Wells, & L. M. Posey (Eds.), Pharmacotherapy: A pathophysiologic approach, 3rd ed., pp. 181–193. Stamford, CT: Appleton & Lange. Karch, A. M. (2002). Lippincott’s Nursing drug guide. Philadelphia: Lippincott Williams & Wilkins. 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