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Pep$de Preformula$on: Physicochemical Proper$es Evalua$on Christopher A. Rhodes, Ph.D. President and CEO Pep$de Preformula$on Outline Pep$de Physicochemical Proper$es What Do We Need to Know and Why? Tools for Evalua$on of Solubility and Stability Modifying Pep$de Proper$es Pharmaceu$cal Development Roadmap 5/3/2015 TIDES Workshop Physicochemical Proper$es 2 Pep$de Physicochemical Proper$es Common Solids Proper$es •  Amorphous powder -­‐ isolated by lyophiliza$on •  Poor powder flow proper$es •  Bulk density is low -­‐ can be compacted easily •  Hygroscopic •  Stable frozen at -­‐20C or -­‐80C in most cases Common Solu$on Proper$es •  Unstable in water and pH > 8 or pH < 4 •  Solubility is pH, buffer and salt concentra$on dependent •  Physical precipita$on over $me as fibrils, par$cles, etc… •  Stable frozen or at 2-­‐8C 5/3/2015 TIDES Workshop Physicochemical Proper$es 3 What Do We Need to Know and Why? How will solid drug substance be handled? •  Research lab and in scale-­‐up •  Transfer processes for poorly flowing solid •  Bulk storage condi$on and as useful aliquots •  Special humidity controls needed for weighing •  Will solids be weighed in a glove box? •  O_en stored in plas$c bag / drum liner / fiber drum at -­‐20C or -­‐80C 5/3/2015 TIDES Workshop Physicochemical Proper$es 4 What Do We Need to Know and Why? What do we need to know for formula$on? •  Dose or dose range for animal and human •  Injec$on route (IM, SC, IV) •  Dictates volume per dose and excipients •  Direct injec$on IV or diluted into infusion bag •  Bioavailability and PK profile •  O_en a diagnos$c for injec$on site precipita$on •  Exposure desired – immediate release or sustained exposure? •  Storage o_en 2-­‐8C, some$mes frozen 5/3/2015 TIDES Workshop Physicochemical Proper$es 5 Contraints for Injectables What is the volume limita$on for SC Injec$on? For IM Injec$on? For IV Injec$on? Osmolarity? 5/3/2015 TIDES Workshop Physicochemical Proper$es 6 Pharmaceu$cal Development of an IV Injec$on Formula$on Current clinical formula$on for phase 1 study IV injec$on –  15 mg/ml in phosphate buffer with tonicity modifiter –  Dilu$on into IV bag from a smaller volume (5 to 15 ml) –  Poten$al for SC injec$on? Human Dose mg/kg 0.1 0.3 1.0 3.0 8.0 10.0 DP Volume 15 mg/ml 0.4 1.3 4.3 13.0 34.7 43.3 Based on 65 kg human DP Volume 50 mg/ml 0.13 0.39 1.3 3.9 10.4 13 DP Volume 100 mg/ml 0.065 0.195 0.65 1.95 5.2 6.5 Dose fits in 5 ml vial New formula$on target is ~50 mg/ml due to aqueous solubility constraints Vial size will be 5, 10, or 20 mL depending on effec$ve dose 5/3/2015 TIDES Workshop Physicochemical Proper$es 7 Tools for Physicochemical Proper$es Evalua$on •  Solubility at solu$on satura$on •  Water (determine the pH) •  Phosphate buffered saline with pH adjusted to 7.4 •  pH solubility profile (make sure you adjust pH) •  Solubility determina$on •  Visual / nominal screen for gross observa$ons •  UV or HPLC concentra$on a_er filtra$on •  Solubility in blood / injec$on site? 5/3/2015 TIDES Workshop Physicochemical Proper$es 8 What is the nature of the pep$de in solu$on? •  Dynamic light scalering •  Observa$on of solu$on monomer or higher order structures •  Higher order structures can be on the path to agglomera$on, aggrega$on, precipita$on, fibril forma$on •  Higher order structure may be purposeful to enhance PK proper$es (lipidated pep$des) 5/3/2015 TIDES Workshop Physicochemical Proper$es 9 Dynamic Light Scalering Hydrodynamic Radius Typical Monomer 1 to 2 nm Hydrodynamic Radius 5 to 7 nm: Higher order structure 5 to 7 pep$des 5/3/2015 TIDES Workshop Physicochemical Proper$es 10 What happens on injec$on? •  Is the pep$de precipita$ng at the inject site? •  Plasma compa$bility assay mimics •  Nephelometric analysis •  Precipita$on •  UV / Vis plate reader assay •  Precipita$on observa$on at 600 nm •  Formula$ons added to PBS, PBS w/ HSA, or plasma 5/3/2015 TIDES Workshop Physicochemical Proper$es 11 Precipita$on on injec$on predic$on Plasma compa$bility using BSA 1 absorbance at680 nM 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.5 1 1.5 2 2.5 3 concentra$on (mg/mL) Compara$ve precipita$on with different formula$on excipients 5/3/2015 TIDES Workshop Physicochemical Proper$es 12 Drug Substance Modifica$on Salt prepara$on •  TFA or acetate salt is typically isolated in pep$de synthesis •  Evaluate the usefulness of other salts for varying solubility •  Or for ease of dissolu$on in formula$ng drug product •  Small scale $tra$on of an insoluble acid with base is easy •  Difficult on a 100 to 1 kg scale – example Modifying Proper$es •  Modify the solubility of pep$de for suspension formula$on •  Or for solubiliza$on in alternate formula$ons (non-­‐aqueous) 5/3/2015 TIDES Workshop Physicochemical Proper$es 13 Pharmaceu$cal Development Pre-­‐formula$on –  pH solubility profile (is the drug soluble where it is stable? –  pH stability and buffer selec$on at 0.1 or 1 mg/ml Co-­‐solvent solubility §  Commonly used parenteral co-­‐solvents screening for solubiliza$on §  Addi$ve to prevent precipita$on on stability at high concentra$on Formula$on op$miza$on –  Final screening at selected pH range, at concentra$on –  Prototypes (3-­‐4) on stability (5, 25, 40C) for 3 months 5/3/2015 TIDES Workshop Physicochemical Proper$es 14 Pharmaceu$cal Development Vial and syringe for early development –  Dosing flexibility and manufacturer availability Pre-­‐filled syringe aRrac$ve for larger volumes (1-­‐2 ml) –  Need to know the dose so o_en challenging to use in early development Pen injec$on / cartridge – may be alrac$ve for later development and commercializa$on 5/3/2015 TIDES Workshop Physicochemical Proper$es 15 Pharmaceu$cal Development Roadmap: Preformula$on and Early Formula$on pH Solubility
Profile
pH Buffer
Stability
1. High solubility at pH > 6.5 2. Buffer strength affects solubility Best stability at pH~7 (1 mg/ml) 110 100 90 80 70 60 50 40 30 20 10 0 98 89 91 95
90
2 0
5.0 5.5 6.0 6.5 7.0 7.5 Solubility in
Co-Solvent
High Conc
Stability
High solubility in Excipient screen (50 mg/ml) NMP, DMSO, DMA 3 Months
Stability
3-­‐4 Candidates on stability, Na Salt vs Acid pH 7 citrate-­‐PO4 best > clinical pH 7.5 (control) > Phosphate pH 7 >> pH 8 or no buffer citrate-PO4, pH=6.5
citrate-PO4, pH=7.0
citrate-PO4, pH=6.5, 0.05% PS20
citrate-PO4, pH=7.0, 0.05% PS20
control
16 1 Formula$on pH buffer screening at 70°C
100
Purity (%)
Concentra$on (mg/mL) Preformula$on 1
2
3
4
Time (weeks)
pH 5/3/2015 TIDES Workshop Physicochemical Proper$es 16 Pep$de Preformula$on Understand Basic Pep$de Physicochemical Proper$es Carefully consider what Do We Need to Know and Why? Simple Tools for Evalua$on of Solubility and Stability Will Pep$de Structure be Modified? Is a Salt Needed Outline Pharmaceu$cal Development Roadmap 5/3/2015 TIDES Workshop Physicochemical Proper$es 17 BACKUP SLIDES 5/3/2015 TIDES Workshop Physicochemical Proper$es 18