In-situ freeze-drying - forming amorphous solids directly within capsules: An investigation of dissolution enhancement for a poorly soluble drug

TY - JOUR

T1 - In-situ freeze-drying - forming amorphous solids directly within capsules: An investigation of dissolution enhancement for a poorly soluble drug

AU - Alqurshi, Abdulmalik

AU - Royall, Paul G.

AU - Chan, K. L. Andrew

PY - 2017/6/6

Y1 - 2017/6/6

N2 - Conversion into the amorphous form enhances the dissolution of poorly soluble drugs, however the barrier to market for medicines containing an amorphous drug is poor stability. The aim was to produce the amorphous form of a drug within a capsule, without thermal or mechanical stress during manufacture. To facilitate this aim, the mechanism for drug-polymer interaction was explored. Nifedipine and polyvinylpyrrolidone were dissolved in tert-butanol at different drug/polymer ratios. These solutions were dispensed into gelatin capsules and freeze-dried. Differential scanning calorimetry (DSC) & novel FT-IR analysis based on peak symmetry measurements confirmed the absence of crystallinity when polyvinylpyrrolidone exceeded 50%w/w. Capsules containing 10mg of nifedipine were amorphous and stable for over 3 months at ≈40oC. Evidence of hydrogen bonding between the N-H group of nifedipine and the C=O group of PVP was observed and this interaction inhibited nifedipine crystallisation. PVP’s high affinity for water and the nifedipine-polymer interaction lead to a significant dissolution rate enhancement. The freeze-dried capsule, 10%w/w nifedipine/PVP, had the highest dissolution rate constant of 0.37±0.05min-1, and the lowest time to achieve 50% dissolution or t1/2 of 1.88±0.05min. This formulation reached 80% dissolved in less than 6min whereas the equivalent marketed liquid filled nifedipine capsule took 3 times longer to reach 80% dissolution.

AB - Conversion into the amorphous form enhances the dissolution of poorly soluble drugs, however the barrier to market for medicines containing an amorphous drug is poor stability. The aim was to produce the amorphous form of a drug within a capsule, without thermal or mechanical stress during manufacture. To facilitate this aim, the mechanism for drug-polymer interaction was explored. Nifedipine and polyvinylpyrrolidone were dissolved in tert-butanol at different drug/polymer ratios. These solutions were dispensed into gelatin capsules and freeze-dried. Differential scanning calorimetry (DSC) & novel FT-IR analysis based on peak symmetry measurements confirmed the absence of crystallinity when polyvinylpyrrolidone exceeded 50%w/w. Capsules containing 10mg of nifedipine were amorphous and stable for over 3 months at ≈40oC. Evidence of hydrogen bonding between the N-H group of nifedipine and the C=O group of PVP was observed and this interaction inhibited nifedipine crystallisation. PVP’s high affinity for water and the nifedipine-polymer interaction lead to a significant dissolution rate enhancement. The freeze-dried capsule, 10%w/w nifedipine/PVP, had the highest dissolution rate constant of 0.37±0.05min-1, and the lowest time to achieve 50% dissolution or t1/2 of 1.88±0.05min. This formulation reached 80% dissolved in less than 6min whereas the equivalent marketed liquid filled nifedipine capsule took 3 times longer to reach 80% dissolution.

KW - Nifedipine

KW - PVP

KW - amorphous

KW - Freeze-drying

KW - Capsules

KW - dissolution rate enhancement

KW - thermal analysis

KW - light microscopy

KW - FTIR

U2 - 10.1038/s41598-017-02676-2

DO - 10.1038/s41598-017-02676-2

M3 - Article

SN - 2045-2322

VL - 7

JO - Scientific Reports

JF - Scientific Reports

M1 - 2910

ER -