Application of a Stable Isotope Approach to Evaluate Impact of Changes in Manufacturing Parameters for an Immediate-Release Tablet.

There is continued emphasis from the various worldwide regulatory agencies to ensure that the pharmaceutical industry fully understands the products they are developing. This emphasis is seen via development of quality-by-design (QbD) publications and guidelines generated by the International Committee on Harmonization. The challenge to meet these expectations is primarily associated with the generation of in vivo data (eg, pharmacokinetic data) that is resource intensive. A technique reducing the resources needed to generate this in vivo data permits a more extensive application of QbD principles. This paper presents the application of stable isotopes in pharmacokinetic studies. The data show that the use of stable isotopes can significantly reduce the number of subjects required for a study. This reduction in subjects thus translates into a significant reduction in resources and time needed to generate the required in vivo data to support QbD.

The Effect of Food and Formulation on the Pharmacokinetics, Safety, and Tolerability of GSK1322322 in Healthy Volunteers.

GSK1322322 is the first in a new class of antibiotics that inhibit peptide deformylase, necessary for bacterial protein maturation. Previously, low absolute bioavailability was observed for the 1500-mg oral tablet formulation, resulting in a less than dose-proportional increase from the 1000-mg dose. Furthermore, high variability of pharmacokinetic (PK) parameters within cohorts was suggested to be associated with differences in body weight. This open-label, randomized, 4-period, crossover, single-dose phase I study in healthy individuals compared the PK, safety, and tolerability of free base oral tablets under fasted or fed conditions with intravenous and oral mesylate salt solution of GSK1322322 under fasted conditions. Absolute bioavailability of GSK1322322 1500-mg free base tablets under fasted conditions, fed conditions, and oral mesylate salt solution was 57%, 77%, and 92%, respectively. Moderate-fat/calorie food intake increased area under the concentration-time curve (AUC0-∞) by 36%, maintained maximum observed concentration (Cmax), and delayed time to Cmax. It appeared that AUC0-∞ decreased with body weight, whereas clearance increased. GSK1322322 administration resulted in only mild-to-moderate adverse events. These results support future clinical investigations of the free base oral tablet formulation of GSK1322322 1500 mg after intake of a moderate-fat/calorie meal, including further investigation of a potential weight-based dosage change.

Stability enhancement of drug layered pellets in a fixed dose combination tablet.

The purpose of this research was to develop a stable fixed dose combination tablet for a model DPP-IV inhibitor and metformin hydrochloride. The dipeptidyl peptidase IV (DPP-IV) inhibitor was particularly challenging to formulate due to its significant chemical instability and moisture sensitivity. Various formulation strategies were investigated and placed on accelerated stability to determine the lead approach and critical quality attributes. The lead formulation investigated was a drug layered pellet containing the DPP-IV inhibitor, which was further coated with various seal coats and moisture barriers, then compressed into a tablet with compression aids and granulated metformin hydrochloride. The investigations revealed that the drug layered pellets compressed into a fixed dose combination tablet yielded a unique stability enhancement. The stability was highly dependent on the final tablet water content and could be further improved by the addition of moisture barrier coatings. A fundamental understanding of the key critical quality attributes for the fixed dose combination product containing a DPP-IV inhibitor and metformin hydrochloride as an oral solid dosage form were established. This research identified a formulation approach to enable a successful commercial product to be developed.

A novel method to radiolabel gastric retentive formulations for gamma scintigraphy assessment.

PURPOSE: To develop a robust radiolabeling technique to enable evaluation of difficult to radiolabel gastric retentive formulations using gamma scintigraphy. The use of a successful radiolabel will allow accurate assessment of the gastric residence time of the formulations. MATERIALS AND METHODS: The retention of two radionuclides, indium ((111)In) and samarium ((153)Sm), with and without further processing to improve radiolabel performance were evaluated in simulated gastric pH in vitro. The most successful formulation from the in vitro screening was further evaluated in preclinical and clinical studies. RESULTS: In vitro evaluation revealed significant radionuclide leakage at pH 1.5 for most radiolabeling attempts. Radionuclide leakage at pH 4.5 was less pronounced. The most successful radiolabel was formulated by adsorbing indium chloride onto activated charcoal, followed by entrapment in a cellulose acetate polymer melt. This provided the best radiolabel retention under both pH conditions in vitro. The radiolabel also proved to be successful during preclinical and clinical evaluations, allowing evaluation of gastric retention performance as well as complete gastrointestinal transit. CONCLUSION: A simple, yet robust radiolabel was developed for gastric retentive formulations to be evaluated pre-clinically or in a clinical setting by entrapping the radionuclide in an insoluble polymer through a simple polymer melt process.

Impact of formulation excipients on human intestinal transit.

The accelerating effect of polyethylene glycol 400 on small intestinal transit has been previously reported. The aim of this study was to investigate the influence of other solubility-enhancing excipient, propylene glycol, D-alpha-tocopheryl-polyethylene glycol-1,000 succinate (VitE-TPGS) and Capmul MCM, on human intestinal transit. A 5-g dose of each excipient was administered to seven healthy male subjects. Propylene glycol and VitE-TPGS were administered dissolved in 150 mL water. Capmul MCM was administered in the form of four 000 hard gelatin capsules to mask its taste and then given with 150 mL water. On a separate occasion, 150 mL water was administered as the control. Each formulation was radiolabelled with technetium-99 m to follow its transit using a gamma camera. The mean small intestinal transit times were 234, 207, 241 and 209 min for the control, propylene glycol, VitE-TPGS and Capmul MCM treatments, respectively. Although there were differences in the small intestinal transit times for the excipients investigated compared with the control, none of the results were statistically significant. Unlike polyethylene glycol 400 at the same dose of 5 g, the excipients tested (propylene glycol, VitE-TPGS and Capmul MCM) had little or no impact on small intestinal transit.

Excipient effects on gastrointestinal transit and drug absorption in beagle dogs.

Previous work has shown that polyethylene glycol 400 (PEG 400) has an accelerating effect on gastrointestinal transit and a modulating influence on drug absorption in humans. The aim of this study was to assess the impact of various excipients, PEG 400, propylene glycol, d-alpha-tocopheryl-polyethylene glycol-1000 succinate (TPGS) and Labrasol on gastrointestinal transit and drug absorption in four beagle dogs using scintigraphy. Each dog received, on five separate occasions, water (control) or a dose of excipient equivalent to 1 g PEG 400, 2 g propylene glycol, 1 g TPGS or 2 g Labrasol dissolved in water and administered in the form of two capsules. The model drugs ampicillin (200mg) and antipyrine (100mg) were co-administered in the capsules. The capsule solutions were radiolabelled with technetium-99m to follow their transit using a dual-headed gamma camera, and blood samples were collected to determine drug pharmacokinetics. On a separate occasion, the drugs were dissolved in saline and given intravenously. The capsules rapidly disintegrated in the stomach liberating their liquid contents. The mean small intestinal transit times for the different treatments (control, PEG 400, propylene glycol, TPGS and Labarasol) were 183, 179, 195, 168 and 154 min, respectively. The corresponding mean absolute oral bioavailability figures were 36, 32, 39, 42 and 32% for ampicillin and 76, 74, 85, 73 and 74% for antipyrine, respectively. The transit and bioavailability data for the excipient treatments were not significantly different from the control. In summary, these excipients, at the doses administered, have limited influence on gastrointestinal transit and drug in beagle dogs.

Concentration-dependent effects of polyethylene glycol 400 on gastrointestinal transit and drug absorption.

PURPOSE: The aim of the study was to investigate the effect of different concentrations of polyethylene glycol 400 (PEG 400) on liquid transit through, and ranitidine absorption from, the gastrointestinal tract. METHODS: Six healthy male volunteers received, on four separate occasions, 150 mL water containing 150 mg ranitidine and either 0 (control), 1,2.5, or 5 g PEG 400. The solutions were radiolabeled with technetium-99m to allow their gastrointestinal transit to be followed using a gamma camera. Urine samples were collected over a 24-h period to assess the amount of ranitidine excreted and hence absorbed. RESULTS: No significant differences in gastric emptying were noted between the four solutions. In contrast, the presence of 1, 2.5, and 5 g PEG 400 reduced the mean small intestinal transit times of the solutions by 9, 20, and 23%, respectively, against the control. In terms of drug absorption, the mean cumulative amount of ranitidine excreted was reduced by 38% in the presence of both 2.5 and 5 g PEG 400, although it was significantly increased by 41% in the presence of 1 g PEG 400. CONCLUSIONS: The results show that low concentrations of PEG 400 enhance the absorption of ranitidine possibly via modulation of intestinal permeability, while high concentrations have a detrimental effect on ranitidine absorption presumably via a reduction in the small intestinal transit time.