Application of the GastroDuo as an in Vitro Dissolution Tool To Simulate the Gastric Emptying of the Postprandial Stomach.

In the postprandial stomach, processes such as secretion, digestion, and gastric emptying all occur simultaneously. Therefore, the system is highly heterogeneous and dynamically changing, for instance, in terms of various physicochemical parameters such as pH value or viscosity. Thus, the administration of a drug together with food can result in highly variable drug plasma concentrations, which may affect the efficacy and safety of the pharmacotherapy. In this work, the pharmacokinetic (PK) data obtained from two fed-state bioequivalence studies with the immediate release (IR) drug products Viagra (sildenafil) and Adenuric (febuxostat) have been analyzed. This evaluation revealed that basically three characteristic types of onset behaviors of drug plasma concentration can be distinguished. It was hypothesized that the different types of onset behaviors were mainly caused by the interplay between gastric drug dissolution and gastric emptying. To study this interplay in vitro, a biopredictive dissolution tool-GastroDuo-was developed and used for both drug products. Therefore, three different test programs have been applied to simulate certain aspects of the postprandial human stomach, which included dynamic pH changes, gastric peristalsis, and the kinetics of gastric emptying. Specifically, the behavior of noncaloric fluids by the so-called "Magenstrasse" was taken into deeper consideration. The experiments revealed that the dissolution and emptying behavior of the two drug products were affected in different ways by the three test programs. The in vitro data nicely explained the tendencies of the drug products for certain types of onset behaviors observed in the PK data. While Viagra was strongly affected by simulated peristalsis, Adenuric was more sensitive to the simulated emptying kinetics. This work clearly demonstrated the important role of gastric fluid emptying for the onset of drug plasma concentration after oral administration of IR formulations in the fed state. Moreover, this was the first study in which GastroDuo was applied as a biopredictive in vitro model which is able to simulate crucial parameters of the human stomach (e.g., pH profiles and gastric emptying) in a realistic manner.

Bioequivalence of Sandoz methylphenidate osmotic-controlled release tablet with Concerta® (Janssen-Cilag).

The aim was to assess the bioequivalence of Sandoz methylphenidate osmotic-controlled release (OCR) tablets (Sandoz [Methylphenidate[ MPH OCR) with Concerta®, a methylphenidate formulation indicated for the treatment of attention deficit/hyperactivity disorder (ADHD). Four open-label, randomized, single-dose, two-way crossover bioequivalence studies were conducted in healthy subjects: three fasting studies with 54-, 36- and 18-mg doses of methylphenidate, and one fed study with the 54-mg dose. The d- and l-threo-methylphenidate plasma levels were quantified using liquid chromatographic methods with tandem mass spectrometry (LC MS/MS). Bioequivalence of the formulations was accepted if the 90% geometric confidence intervals of the ratio of least-squares means of Sandoz MPH OCR to Concerta® of ln-transformed area under the curve (AUC0-t ) and C max were within the acceptance range of 80-125%. All studies met the bioequivalence criteria, and 90% geometric confidence intervals for AUC0-t and C max were within the predefined range. All plasma concentration time curves for Sandoz MPH OCR under fasting conditions showed a biphasic profile comparable with Concerta®, confirmed by bioequivalence of the partial metrics AUC0-2h, AUC2-24 h, C max(0-2 h) and C max(2-24 h). Both products were well tolerated and no relevant differences in the safety profiles were observed. It was concluded that Sandoz MPH OCR is bioequivalent to Concerta® in terms of rate and extent of absorption when administered as a single dose of one extended-release tablet of 54, 36, or 18 mg under fasting conditions and at a dose of 54 mg under fed conditions.

Clinical development of two innovative pharmaceutical forms of leuprorelin acetate.

OBJECTIVES: Two innovative pharmaceutical forms of leuprorelin acetate have been developed as 1-month and 3-month implants for the treatment of advanced hormone-dependent prostate cancer. These products contain active substance dispersed homogeneously in a biodegradable polymer. Here we present the key results from the clinical development of these slow-release implant formulations of leuprorelin. METHODS: Two therapeutic studies of the 1-month implant were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Enantone) as the active control; and a single-arm study of the leuprorelin implant. For the 3-month implant, four therapeutic studies were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Trenantone) as the active control; a single-arm study of the leuprorelin implant; and two long-term studies with the 3-month implant administered twice, either 12 or 16 weeks apart. A pooled analysis of data from the comparator-controlled and single-arm studies of the 3-month implant was also conducted. The main inclusion criterion for all studies was histologically confirmed advanced prostate cancer, with primary endpoints based around successful testosterone suppression (≤0.5 ng/ml). RESULTS: In the comparator-controlled studies, both implants were as effective as the microspheres for achieving successful testosterone suppression and normalization of prostate-specific antigen (PSA) levels. Data from the single-arm and long-term studies were consistent with those from the comparator-controlled studies. In the pooled analysis, significantly more patients treated with the 3-month implant achieved successful testosterone suppression compared with the comparator (p ≤ 0.01). The safety profile of the implants in the comparator-controlled studies was similar to that of the prolonged-release microsphere formulation, and consistent with that of the luteinizing hormone-releasing hormone agonist class. CONCLUSIONS: The innovative 1-month and 3-month implants of leuprorelin acetate are at least as effective as leuprorelin acetate prolonged-release microspheres for achieving successful testosterone suppression and normalization of PSA in men with advanced hormone-dependent prostate cancer, with a comparable safety profile.