Bioavailability Enhancement and Food Effect Elimination of Abiraterone Acetate by Encapsulation in Surfactant-Enriched Oil Marbles

Pharmaceutical Product Characterization and Manufacturability of Surfactant-Enriched Oil Marbles with Abiraterone Acetate

The present study investigates the physicochemical properties and stability of a novel lipid-based formulation-surfactant-enriched oil marbles containing abiraterone acetate. While the biopharmaceutical performance of this formulation has been reported recently, this study aims to fill the gap between a promising in vivo performance and industrial applicability. A series of techniques were employed to assess the solid-state characteristics of oil marble cores along with their physicochemical properties upon stability testing. The chemical stability of abiraterone acetate in the formulation was also investigated. The core of the formulation was found to be stable both physically and chemically over 12 months of storage. The in vitro performance of stressed samples was evaluated using a dissolution experiment. The formulation has successfully self-emulsified upon incubation in bio-relevant media, resulting in a fast and complete API release. An important issue connected with the excipient used as a covering material of oil marbles has been identified. The seemingly insignificant water sorption caused agglomeration of the oil marbles and consequently compromised the dissolution rate in some of the stressed samples. Replacing HPMC with lactose as a covering material resulted in more favorable properties upon storage. Overall, it has been shown that oil marbles are an industrially applicable concept of the solidified lipid-based formulation.

Open-Label, Phase I, Pharmacokinetic Studies in Healthy Chinese Subjects to Evaluate the Bioequivalence and Food Effect of a Novel Formulation of Abiraterone Acetate Tablets

Purpose

Abiraterone acetate tablets (I)(N-AbA) is a novel tablet co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). This study aimed to compare the pharmacokinetics, bioequivalence, safety, and food effects of N-AbA with the reference ZYTIGA^® (R-AbA) in healthy Chinese male subjects.

Patients and Methods

This study was conducted in three parts. Part I was an open, dose-escalation trial conducted in 16 Chinese healthy males; Part II was a randomized, open-label, 2 × 4 crossover, single-dose bioequivalence trial conducted in 36 subjects; Part III was a randomized, 3 × 3 crossover trial conducted on 24 volunteers to investigate the effect of food on the pharmacokinetics of N-AbA.

Results

The exposure (AUC_0-∞) and maximum concentration (C_max) of abiraterone and excipient SNAC were linear in the range of 75–450 mg dose. The bioavailability of N-AbA 300 mg was equivalent to that of R-AbA 1000 mg. The drug exposure of prednisone and prednisolone was not affected by SNAC co-administration. The C_max of orally administered abiraterone as R-AbA in a modified fed state was 5.9 times and AUC_0-∞ was 4.3 times, respectively, higher than those in of orally administered abiraterone as N-AbA in a high-fat diet. The C_max and AUC_0-∞ of orally administered abiraterone as N-AbA on a high-fat diet were 2.2 times and 2 times, respectively, higher than those on a fasting state. All adverse events reported in the three parts of the study were grade 1 or 2, and no serious adverse events were reported.

Conclusion

These three Phase I trials showed that N-AbA and excipient SNAC had excellent linear pharmacokinetic characteristics. A single dose of N-AbA 300 mg was bioequivalent to R-AbA 1000 mg in healthy subjects under fasting conditions. Meanwhile, SNAC had no effect on the pharmacokinetics of prednisone and prednisolone. The effect of food on N-AbA was significantly lower than that on R-AbA.

Development of Self-Microemulsifying Drug Delivery System to Improve Nisoldipine Bioavailability: Cell Line and In Vivo Evaluations : Development of Self-Microemulsifying Drug Delivery System

The authors attempted to fabricate a novel lipid-based formulation of a lipophilic drug, nisoldipine (NISO). As NISO belongs to BCS class 2 drug, it suffers from low bioavailability (5%). Hence, the research was intended to ameliorate oral bioavailability of NISO via intestinal lymphatic transport. The NISO loaded self microemulsifying drug delivery system (SMEDDS) (NISO SMEDDS) was prepared using Peceol, Cremophor EL, and Transcutol HP. The Cremophor EL and Transcutol HP at 1:1 ratio showed maximum microemulsifying area, and average globule size was 16.78 ± 0.97 nm with PDI 0.121 ± 0.024. Cellular uptake studies (confocal microscopy and flow cytometry) using Caco-2 cells depicted higher fluorescence with coumarin-6 loaded SMEDDS as that of coumarin-6 solution which indicated deeper penetration. Mean fluorescence intensity (MFI) of coumarin-6 loaded SMEDDS was significantly improved (9.92-fold) in contrast to coumarin-6 solution. The NISO SMEDDS showed enhanced permeability (5.02 times) across Caco-2 cells compared to NISO suspension. The bioavailability improvement with NISO SMEEDS was 2.14 times relative to suspension, and lymphatic uptake was involved in oral absorption of NISO SMEDDS.

Validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport of drugs

BACKGROUND AND PURPOSE

Lymphatic transport of drugs after oral administration is an important mechanism for absorption of highly lipophilic compounds. Direct measurement in lymph duct cannulated animals is the gold standard method, but non-invasive cycloheximide chylomicron flow blocking method has gained popularity recently. However, concerns about its reliability have been raised. The aim of this work was to investigate the validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport using model compounds with high to very high lipophilicity, that is, abiraterone and cinacalcet.

EXPERIMENTAL APPROACH

Series of pharmacokinetic studies were conducted with abiraterone acetate and cinacalcet hydrochloride after enteral/intravenous administration to intact, lymph duct cannulated and/or cycloheximide pre-treated rats.

KEY RESULTS

Mean total absolute oral bioavailability of abiraterone and cinacalcet was 7.0% and 28.7%, respectively. There was a large and significant overestimation of the lymphatic transport extent by the cycloheximide method. Mean relative lymphatic bioavailability of abiraterone and cinacalcet in cycloheximide method was 28-fold and 3-fold higher than in cannulation method, respectively.

CONCLUSION AND IMPLICATIONS

Cycloheximide chylomicron flow blocking method did not provide reliable results on lymphatic absorption and substantially overestimated lymphatic transport for both molecules, that is, abiraterone and cinacalcet. This non-invasive method should not be used for the assessment of lymphatic transport and previously obtained data should be critically revised.

The effect of drug loading on the properties of abiraterone-hydroxypropyl beta cyclodextrin solid dispersions processed by solvent free KinetiSol® technology

Abiraterone is a poorly water-soluble drug used in the treatment of prostate cancer. In our previous study, we reported that KinetiSol® processed solid dispersions (KSDs) based on hydroxypropyl β-cyclodextrin (HPBCD) showed improved dissolution and pharmacokinetics of abiraterone. However, the nature of abiraterone-HPBCD interaction within the KSDs or the effect of drug loading on the physicochemical properties and in vivo performance of HPBCD-based KSDs remain largely unknown. We hypothesize that KinetiSol technology can prepare abiraterone-HPBCD complexes within KSDs and that increasing the drug loading beyond an optimal point reduces the in vitro and in vivo performance of these KSDs. To confirm our hypothesis, we developed KSDs with 10-50% w/w drug loading and analyzed them using X-ray diffractometry and modulated differential scanning calorimetry. We found that KSDs containing 10-30% drug were amorphous. Interestingly, two-dimensional solid-state nuclear magnetic resonance and Raman spectroscopy indicated that the abiraterone-HPBCD complexes were formed. At elevated temperatures, the 10% and 20% drug-loaded KSDs were physically stable, while the 30% drug-loaded KSD showed recrystallization of abiraterone. In vitro dissolution and in vivo pharmacokinetic performances improved as the drug loading decreased; we attribute this to increased noncovalent interactions between abiraterone and HPBCD at lower drug loadings. Overall, the 10% drug loaded KSD showed a dissolution enhancement of 15.7-fold compared to crystalline abiraterone, and bioavailability enhancement of 3.9-fold compared to the commercial abiraterone acetate tablet Zytiga®. This study is first to confirm that KinetiSol, a high-energy, solvent-free technology, is capable of forming abiraterone-HPBCD complexes. Furthermore, in terms of in vitro and in vivo performance, a 10% drug load is optimal.