Influence of sorbitol solution on the bioavailability of theophylline

Bioequivalence of a New Pediatric Paracetamol Oral Suspension Compared With a Marketed Formulation in Healthy Adults: A Randomized, Open-Label Study

Background

A new oral paracetamol formulation with the same paracetamol quantity (24 mg/mL) as a marketed formulation but with finer active ingredient particle size and lower amounts of maltitol (5.85 g/dose in the test formulation vs 7.25 g/dose in the reference formulation) and sorbitol (2.4 g/dose vs 2.83 g/dose) was developed.

Objective

Establish the bioequivalence of the new pediatric formulation (test treatment) compared with the marketed formulation (reference treatment).

Methods

This Phase I, open-label trial assigned healthy adult volunteers to a single 42-mL (1 g para-cetamol) dose of test or reference treatment. Participants received both treatments in a randomized order separated by a 72-hour washout period. The primary endpoints were AUC0-tlast (AUC vs time curve from time 0 to last measurable sampling timepoint), Cmax, and tmax. Safety assessments included adverse event, clinical laboratory, and physical examination data.

Results

Thirty-five participants were randomized and treated. The study population was 42.9% women (57.1% men) with a median age of 30 years; most participants were non-Hispanic White. Mean Cmax values were comparable between test and reference products, with a median tmax of 1.00 hour for both. The test/reference ratios (%) (90% CI) for AUC0-tlast and Cmax were 98.69% (96.46, 100.97) and 100.73% (95.63, 106.10), respectively. There were no adverse events or deaths.

Conclusions

The new paracetamol formulation is bioequivalent to the marketed formulation.

Bioequivalence Dissolution Test Criteria for Formulation Development of High Solubility-Low Permeability Drugs

The purpose of the present study was to provide the experimental and theoretical basis of bioequivalence (BE) dissolution test criteria for formulation development of high solubility-low permeability drugs. According to the biowaiver scheme based on the biopharmaceutics classification system (BCS), for BCS class III drugs, a test formulation and a reference formulation are predicted to be BE when 85% of the drug dissolves within 15 min (T_85% < 15 min) in the compendial dissolution test. However, previous theoretical simulation studies have suggested that this criterion may possibly be relaxed for use in practical formulation development. In the present study, the dissolution profiles of 14 famotidine formulations for which BE has been clinically confirmed were evaluated by the compendial dissolution test at pH 1.2 and 6.8. The plasma concentration-time profiles of famotidine formulations were simulated using the dissolution data. In addition, virtual simulations were performed to estimate the range of dissolution rates to be bioequivalent. The fastest and slowest dissolution rates among the famotidine formulations were T_85% = 10 min and T_85% = 60 min at pH 6.8, respectively. The virtual simulation BE study suggested that famotidine formulations can be bioequivalent when T_85% < 99 min. In the case of BCS III drugs, the rate-limiting step of oral drug absorption is the membrane permeation process rather than the dissolution process. Therefore, a difference in the dissolution process has less effect on BE. These results contribute to a better understanding of the biowaiver approach and would be of great help in the formulation development of BCS class III drugs.

Evaluation of Excipient Risk in BCS Class I and III Biowaivers

The objective of this review article is to summarize literature data pertinent to potential excipient effects on intestinal drug permeability and transit. Despite the use of excipients in drug products for decades, considerable research efforts have been directed towards evaluating their potential effects on drug bioavailability. Potential excipient concerns stem from drug formulation changes (e.g., scale-up and post-approval changes, development of a new generic product). Regulatory agencies have established in vivo bioequivalence standards and, as a result, may waive the in vivo requirement, known as a biowaiver, for some oral products. Biowaiver acceptance criteria are based on the in vitro characterization of the drug substance and drug product using the Biopharmaceutics Classification System (BCS). Various regulatory guidance documents have been issued regarding BCS-based biowaivers, such that the current FDA guidance is more restrictive than prior guidance, specifically about excipient risk. In particular, sugar alcohols have been identified as potential absorption-modifying excipients. These biowaivers and excipient risks are discussed here.

The Provisional No-Effect Threshold of Sugar Alcohols on Oral Drug Absorption Estimated by Physiologically Based Biopharmaceutics Model

Sugar alcohols reduce oral drug bioavailability by osmotic effects, but the magnitude of these effects differs among different drugs. This study aimed to identify the drug-related critical attributes of osmotic effects and estimate the impact of a "practical" sugar alcohol dose on the pharmacokinetics of various molecules using modeling and simulation approaches. We developed a physiologically based biopharmaceutics model that considers the dose-dependent effects of sugar alcohols on the gastrointestinal physiology. The developed model captured the effects of sugar alcohols on ranitidine hydrochloride, metoprolol tartrate, theophylline, cimetidine, and lamivudine. Sensitivity analysis provided quantitative insights into the effects of sugar alcohols dependent on different drug permeability. In addition, our developed model indicated for the first time that a high systemic elimination rate is crucial for the reduction in maximum plasma concentration even for highly permeable drugs. Nonetheless, mannitol/sorbitol level of less than 400 mg had minor effects on the pharmacokinetics of the most sensitive drugs, indicating a provisional no-effect threshold dose. This mechanistic approach provides comprehensive estimation of osmotic effects on variety of drugs. Subsequently, these findings may invoke scientific discussion on the criteria for excipient changes in the context of biowaiver guidelines (e.g. biopharmaceutics classification system-based biowaiver).

Use of sorbitol as pharmaceutical excipient in the present day formulations - issues and challenges for drug absorption and bioavailability

Sorbitol is a popular sugar alcohol which has been used as an excipient in formulations of various drugs. Although from a safety perspective the presence of sorbitol in drug formulations does not raise a concern, reports have emerged and these suggest that sorbitol in drug formulations may alter oral absorption and bioavailability of certain drugs. The focus of this article was to review the published literature of various drugs where pharmacokinetic data has been reported for the drug alone versus drug administered with sorbitol and provide perspectives on the pharmacokinetic findings. Interestingly, for BCS class I drugs such as theophylline, metoprolol, the oral absorption, and bioavailability were generally not affected by sorbitol. However, theophylline oral absorption and bioavailability were decreased when sustained release formulation was used in place of immediate release formulation. For drugs such as risperidone (BCS class II) and lamivudine and ranitidine (BCS class III), the solution formulations showed diminished oral bioavailability in presence of sorbitol, whereas cimetidine and acyclovir (BCS class III), did not show any changes in pharmacokinetic profiles due to sorbitol. Finally, the presence of activated charcoal with sorbitol showed different pharmacokinetic outcome for BCS class I and II drugs.

A Modern View of Excipient Effects on Bioequivalence: Case Study of Sorbitol

PURPOSE

To examine the effect of common excipients such as sugars (sorbitol versus sucrose) on bioequivalence between pharmaceutical formulations, using ranitidine and metoprolol as model drugs.

METHODS

Two single-dose, replicated, crossover studies were first conducted in healthy volunteers (N=20 each) to compare the effect of 5 Gm of sorbitol and sucrose on bioequivalence of 150 mg ranitidine or 50 mg metoprolol in aqueous solution, followed by a single-dose, nonreplicated, crossover study (N=24) to determine the threshold of sorbitol effect on bioequivalence of 150 mg ranitidine in solution.

RESULTS

Ranitidine Cmax and AUC0-infinity were decreased by approximately 50% and 45%, respectively, in the presence of sorbitol versus sucrose. Similarly, sorbitol reduced metoprolol Cmax by 23% but had no significant effect on AUC0-infinity. An appreciable subject-by-formulation interaction was found for ranitidine Cmax and AUC0-infinity, as well as metoprolol Cmax. Sorbitol decreased the systemic exposure of ranitidine in a dose-dependent manner and affected bioequivalence at a level of 1.25 Gm or greater.

CONCLUSIONS

As exemplified by sorbitol, some common excipients have unexpected effect on bioavailability/bioequivalence, depending on the pharmacokinetic characteristics of the drug, as well as the type and amount of the excipient present in the formulation. More research is warranted to examine other 'common' excipients that may have unintended influence on bioavailability/bioequivalence.

Multiple-layer, direct-compression, controlled-release system: in vitro and in vivo evaluation

A new approach to achieve controlled drug delivery is demonstrated for a triple-layer tablet, which simultaneously combines the principles of diffusion and dissolution. Heckel's equation was used to characterize the compression behavior of formulation components. A balanced proportion of each component and a model drug (theophylline) were selected to avoid lamination after ejection and ensure coherent compaction. In vitro release profiles over a period of 10 h in different dissolution media and hydrodynamic conditions were similar and resulted in an n value of 0.786, signifying anomalous release kinetics. The n value is calculated from a curve fit to the empirical equation: Mt/Minfinity = Ktn, where Mt and Minfinity denote the amount of drug released at time t and at infinite time, respectively, K denotes the proportionality constant, and n characterizes the type of release mechanism operative during the dissolution process. In vivo study in human subjects after administration of the experimental triple-layer system exhibited a steady rise in plasma concentration up to 7 h. The actual amount of drug absorbed by the body was calculated by the Wagner-Nelson technique, and a linear relationship was observed between the percentage absorbed in vivo and the percentage dissolved in vitro. The proposed triple-layer model appears to provide good correlation between in vitro and in vivo results with maximum flexibility with respect of dose, duration range, and ease of production.