Poly vinylpyrrolidone

Methotrexate disodium (MTX Na) (purity ≥ 99.35%) was purchased from Haihang Industry Co. LTD (Shandong, China). Poly(vinylalcohol) (MW= 9–10 kDa, 80% hydrolysed) (PVA 10 K) and Poly(vinylalcohol) (MW=31–50 kDa, 87–89% hydrolysed) (PVA 50 K) were purchased from Sigma-Aldrich (Dorset, UK). Poly(vinylpyrrolidone) (MW=58 kDa) (PVP) was obtained from Ashland (Kidderminster, UK). Ultrapure water was obtained from a water purification system (Elga PURELAB DV 25, Veolia Water Systems, Dublin, Ireland). All other reagents used were of analytical grade.

TAF (also known as GS-7340) was provided by Gilead Sciences, Inc. TAF and TFV and their stable isotopically labelled (SIL) internal standards (TFV-d6 and TAF-d5) were obtained from Toronto Research Chemicals (Canada). Poly(vinylpyrrolidone) (PVP K29-32; and PVP K90) was provided by Ashland (Kidderminster, UK). Poly(vinyl alcohol) (PVA 9–10 ​kDa) and solvents methanol ≥99.9%, dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) inhibitor-free ≥ 99.9% and acetonitrile (ACN) ​≥ ​99.9% (all HPLC grade), ammonium acetate ≥98%, and Acetic acid ≥99.7% were purchased from Sigma-Aldrich, St. Louis, USA. Two different types of poly(d,l-lactide-co-glycolide) (PLGA) were used, a low viscosity PLGA, Purasorb® PDLG 7502 with a lactide:glycolide ratio of 75:25 and ester end (Purac®, Corbion, Netherlands) (LV-PLGA) and a high viscosity PLGA with a lactide:glycolide ratio of 75:25 and ester end (Viatel® DLG 7503 ​E) (HV-PLGA). Both PLGAs were a donation from Ashland (Kidderminster, UK). All other reagents used in this work were of analytical grade and purchased from Sigma-Aldrich. Elga purified water was used in all cases (Purelab option® Elga LabWater, High Wycombe, UK).

Micronized abiraterone acetate was purchased from Sterling (Cramlington, UK). Polyvinylpyrrolidone was obtained from Ashland (Covington, KY, USA). Soluplus^® was purchased from BASF (Ludwigshafen, Germany). SIF powder was purchased from biorelevant.com, Switzerland. FaSSIF V2 biorelevant medium was prepared according to the manufacturer’s instructions. Lactose monohydrate was purchased from Meggle (Wasserburg am Inn, Germany), sodium deoxycholate was purchased for New Zealand Pharma (Palmerston North, New Zealand), microcrystalline cellulose was purchased from JRS Pharma (Rosenburg, Germany) and crospovidone was purchased from BASF (Florham Park, NJ, USA). All other chemicals were purchased from Sigma (St. Louis, MO, USA).