Investigations on dose proportionality and drug-drug interaction for a fixed-dose combination of trazodone and gabapentin.

OBJECTIVES: To establish dose proportionality for trazodone and gabapentin at fixed ratios of trazodone/gabapentin 2.5/25, 10/100, and 30/300 and investigation of potential drug-drug interaction at a dose of 10/100. MATERIALS AND METHODS: 29 out of 30 healthy subjects completed this single-center, open-label, randomized, 5-period cross-over trial with single-dose fasted administrations. Administrations were separated by a washout period of at least 6 days. Blood samples were drawn until 48 hours post dose. A validated liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was applied for determination of trazodone and gabapentin in plasma. The lower limits of quantitation (LLOQ) were 1.00 ng/mL and 5.00 ng/mL for trazodone and gabapentin, respectively. Adverse events (AEs) were analyzed in the study population descriptively. RESULTS: Plasma concentrations were characterized thoroughly. For trazodone, assessment of proportionality (power model/pairwise-comparison by ANOVA) showed proportionality for AUC over all doses and for Cmax between the middle and high dose. For gabapentin, a less than proportional increase in both metrices was present with a likely proportional increase from 25 to 100 mg only. Considering common bioequivalence criteria, absence of pharmacokinetic interaction was confirmed comparing the combination and individual agents. 23 subjects experienced 53 AEs during the trial, the most frequent being fatigue (20 cases/15 subjects) and dizziness (14 cases/11 subjects). No serious AEs were reported. CONCLUSION: To our knowledge, for the first time, proportionality for trazodone at doses of 2.5 to 30 mg and for gabapentin at doses of 25 to 300 mg was investigated. Absence of a pharmacokinetic interaction was shown.

The Two Main Goals of Bioequivalence Studies.

The principal goal of bioequivalence (BE) investigations has crucial importance and has been the subject of extensive discussions. BE studies are frequently considered to serve as procedures for sensitive discrimination. The BE investigation should be able to provide methods and conditions sensitively identifying relevant differences between drug products if such differences in fact exist. Alternatively, BE studies can be deemed as surrogates of clinical investigations assessing therapeutic equivalence. Bioequivalent drug products will be provided to patients for their benefits. Both points of view are valid since they represent two aspects of product performance. It has been argued that both should be equally sustained and applied. In practice, however, they collide when regulatory conditions and statements are developed. For instance, some regulators prefer to conduct BE studies following single drug administrations since these conditions are considered to provide the highest sensitivity of discrimination between pharmacokinetic profiles and thus, a product's in-vivo performance. Others suggest that, at least for modified-release products, BE investigations should be performed in the steady state since it represents clinical conditions. Preference for one point of view or the other pervades other regulatory statements including suggestions for subjects to be selected in studies and pharmacokinetic measures to be evaluated. An overview is provided on the disturbing inconsistency of statements within and between regulations. It is argued that harmonization would be highly desirable, and relevant recommendations are offered.

Relative bioavailability of a newly developed 5-mg levomethadone hydrochloride IR tablet (L-Polamidon® 5 mg tablets) in comparison with the 5-mg levomethadone hydrochloride oral solution (L-Polamidon® solution for substitution) as reference product.

OBJECTIVES: To establish the relative bioavailability (rBA) between two p.o. 5-mg levomethadone hydrochloride formulations, i.e., L-Polamidon® 5 mg tablets (test) vs. L-Polamidon® solution for substitution (reference). To assess the safety and tolerability of both formulations. SUBJECT AND METHODS: A total of 33 healthy male subjects, aged 29 ± 6 years (BMI: 23.9 ± 2.5 kg/m2) completed this single center, open-label, randomized, 2-period cross-over study with single dose administrations under fasting conditions and coadministration with naltrexone for safety reasons. Administrations of both investigational products were separated by a washout period of at least 2 weeks, i.e., 13 treatmentfree days. The total dose for each subject was 2 x 5 mg resulting in 10 mg levomethadone hydrochloride. For pharmacokinetic evaluation, blood samples were withdrawn until 72 hours postdose. A validated non-stereoselective liquid chromatography-tandem mass spectroscopy method (LC-MS/MS) was applied for the determination of levomethadone in plasma. The lower limit of quantitation was 0.100 ng/mL. Adverse events were descriptively analyzed in the study population. RESULTS: The geometric means of the parameters related with the extent of total exposure of levomethadone, i.e., AUC(0-tlast) and AUC(0-∞), were 244.422 ng x h/mL and 332.999 ng x h/mL for test and 246.837 ng x h/mL and 329.467 ng×h/mL for reference, respectively. The geometric means of the peak exposure for levomethadone, i.e., Cmax, were 8.923 ng/mL for test and 8.635 ng/mL for reference. The point estimates (PEs) of the Test/Reference (T/R) adjusted geometric mean ratios of AUC(0-last), AUC(0-∞), and C(max) were 99.20%, 101.42%, and 104.11%, respectively, and all of them showed 90%-confidence intervals (CIs) within the range of 80.00 - 125.00% as suggested by regulatory requirements for bioequivalence assessment In total, 21 subjects experienced 55 AEs during the study, the most frequently reported AE, i.e., headache, accounted for 13 out of the total 55 AEs (23.6%) and no AEs of severe intensity were reported. CONCLUSIONS: Bioequivalence could be demonstrated in terms of rate and extent of absorption after administration of test and reference products under naltrexone protection. Concerning the safety evaluation, no negative implications on the possible use of the test formulation could be determined.

Bioavailability and pharmacodynamics of two 10-mg estradiol valerate depot formulations following IM single dose administration in healthy postmenopausal volunteers.

OBJECTIVE: To establish the bioequivalence (BE) between two i.m. estradiol valerate (E2V) depot formulations, i.e., Estradiol-Depot 10 mg® (test) and Progynon Depot-10® (reference). To compare the effect of both treatments on the vaginal maturation index and on the increase of the endometrial thickness after administration of both formulations. METHODS: A total of 24 postmenopausal females aged 54.7 ± 5.35 year (BMI 25.84 ± 1.98 kg/m2) completed this BE assessment. The investigation was planned and designed as a single center, openlabel, single dose, cross-over study including 2 periods with 2 treatments and 2 sequences. Baseline levels were obtained for all subjects. Single doses of 10-mg E2V of each product were administered and pharmacokinetics and pharmacodynamics were assessed over 2 weeks with a washout period of 4 weeks. A gas chromatographic-mass spectrometric method with negative chemical ionization and selected ion monitoring was applied, after validation, for the determination of estradiol (E2), estrone (E1) and internal standard estradiol-D4 derivatives. The cytology of the vaginal smear (parabasal, intermediate and superficial cells from lateral wall opposite tip of cervix) was assessed by investigation of ~ 200 cells. The vaginal maturation index (VMI) was calculated by the equation: VMI (%) = (superficial cells × 1) (%) + (intermediate cells × 0.5) (%). Endometrial thickness was measured by transvaginal ultrasonic scans and recorded in mm. RESULTS: The geometric means (Gmeans) of the measured values of Cmax and AUC0-t for E2 were 543.5 pg/ ml and 84,734 pg × h/ml for test and 505.7 pg/ml and 82,660 pg × h/ml for reference, whereas those for E1 were 219.0 pg/ml and 38,950 pg × h/ml for test and 204.9 pg/ml and 37,159 pg × h/ml for reference, respectively. The point estimates (PEs) of the Test/ Reference (T/R) mean ratios of the variables Cmax and AUC0-t for E2 (measured values) were 107.3% and 102.5%, respectively. The PEs of the T/R mean ratios of the variables Cmax and AUC0-t for E1 (measured values) were 106.9% and 105.0%, respectively. Median endometrial thickness increased in Period I from baseline levels of ~ 3 mm (Day -2) to ~ 7 mm (Day 21) after administration of both products without returning completely to baseline prior to the next administration. In Period II, median values of 7 mm were also reached (Day 21) after administration of both products. Median vaginal maturation indices increased in Period I from baseline levels of ranging from 45 - 60% (Day -2) to 86 - 94.5% (Day 21). In Period II maturation indices of ≥ 90% were calculated as baselines (Day -2) and these levels remained constant until the end of the assessment (Day 21) independently from the products. After 21 days of treatment, test and reference presented practically no differences in terms of their effects on endometrial thickness and vaginal maturation index. CONCLUSIONS: The 95% CIs for the T/R mean ratios of AUC0-t and Cmax for E2 and E1 fell within the acceptance limits of 80 - 125% and therefore bioequivalence could be demonstrated for both formulations. The changes in endometrial thickness and the vaginal maturation index indicated that the pharmacodynamic effect is pronounced already after the first administration and that the effect continued notably for longer time compared to the presence of E2 and E1 in plasma. A 4-week washout phase was insufficient to avoid residual pharmacological effects after the administration of both preparations.

Improved therapeutic entities derived from known generics as an unexplored source of innovative drug products.

With a New Drug Application (NDA) innovative drug therapies are reaching the market in a specific dosage form for one or more clinically proven indications of which after expiration of the patent or the data exclusivity copies are launched using Abbreviated New Drug Applications (ANDA). Advanced therapies that emerged from launched molecules during their product life-cycle have gained considerable attention as clinical practice provides evidence for additional therapeutic values, patient centric delivery systems show improved therapeutic outcomes or emerging technologies offer efficiency gains in manufacturing or access to emerging markets. The USA and European regulatory framework has set reasonable regulations in place for these "Supergenerics" or "hybrid" applications. While these regulations are relatively recent the pharmaceutical industry is just starting to use this route for their product development and life-cycle management. From a clinical perspective the potential for advanced product development have been demonstrated. Yet, there is still a lag of common understanding between the different stakeholders regarding the development, application process and commercial incentive in developing enhanced therapeutic entities based on existing drug products for the market.

Lidocaine 8 mg sore throat lozenges in the treatment of acute pharyngitis. A new therapeutic option investigated in comparison to placebo treatment.

An acute pharyngitis is characterised by mild to severe sore throat mostly accompanied by inflammation, throat pain, pain on swallowing, and burning. This randomised, double-blind, placebo-controlled phase III study was conducted for comparison of the efficacy and safety of a newly developed lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl) acetamide, CAS 137-58-6) 8 mg lozenge formulation (Trachisan Halsschmerztabletten) for the treatment of acute sore throat not necessarily to be treated with antibiotics. 240 patients of both genders were enrolled. The study was performed in a single centre setting and consisted of two parts. A 2-h stationary phase (single dose treatment) was directly followed by a 46-h ambulatory phase, where patients were allowed to take up to a maximum of 11 further lozenges (multiple dose treatment). Pain intensity was assessed via Visual Analogue Scale during the course of the study. Moreover, the global efficacy and tolerability of the treatments were assessed. Lidocaine 8 mg sore throat lozenges were found to be superior to placebo for all efficacy parameters investigated. For the primary efficacy parameter, area under the curve of pain intensity from baseline over 2 h (AUC(0-2h)), i.e. after single-dose treatment, a significant treatment difference with a p-value of p < 0.001 in favour of the verum treatment could be demonstrated. Significant superiority could also be demonstrated for the descriptive AUC(0-48h) values, reflecting the treatment effect during the ambulatory multiple dose phase. Pain relief, minimum pain intensity, meaningful pain relief and the time of onset of meaningful pain relief as well as the assessments of global efficacy underlined the superiority of the treatment with lidocaine 8 mg sore throat lozenges. Global tolerability of the verum treatment was rated as "good" or "very good" in the majority of cases, the number of study drug related adverse events was low and evenly distributed to both treatment groups. Therefore, the results of the trial emphasise lidocaine 8 mg sore throat lozenges to be a favourable option in the treatment of pain symptoms of an acute sore throat.

Determination of hyperforin in mouse brain by high-performance liquid chromatography/tandem mass spectrometry.

Hyperforin is one of the essential active ingredients of St. John's wort extract, which is used as an antidepressant for mild to moderately severe depressions. In vitro and in vivo data as well as several clinical studies and meta analyses have confirmed the pharmacological effect of treatment with hyperforin-containing preparations. However, little is known about the brain availability of hyperforin until now. Accordingly, a highly sensitive and selective LC/MS method for this purpose was developed and validated. This method proved suitable for the determination of hyperforin in mouse brain, after oral administration of hyperforin sodium salt and St. John's wort extract. This method involves liquid-liquid extraction of hyperforin with ethyl acetate followed by separation with rapid reversed-phase high-performance liquid chromatography and tandem mass spectrometry detection using electrospray ionization. Excellent linearity was obtained for the entire calibration range from 0.25 to 10 ng/mL (corresponding to 2.5-100 ng/g brain tissue concentration, calculated with the factor derived from sample processing) with an average coefficient of correlation of 0.9992. The recovery of hyperforin from mouse brain homogenates was between 71.4 and 75.3% with a relative standard deviation of less than 3%. Validation assays for the lower limit of quantitation yielded an accuracy of 5.8%. Intraday accuracy and precision for the developed method were between 4.6 and 10.6% and 4.3-8.4%, respectively, while the interday parameters varied between 6.7 and 12.2% for accuracy and 2.0-5.0% for precision. After the method validation, hyperforin brain levels in mice, treated with 15 mg/kg hyperforin (either as the sodium salt or as 5% St. John's wort extract), were investigated. The average concentration of hyperforin found for the sodium salt group was 28.8+/-10.1 ng/g of brain (n = 8), which was somewhat higher than the hyperforin concentration of 15.8+/-10.9 ng/g of brain (n = 8), determined in the extract-treated group. This method is robust, selective, and highly sensitive and represents an appropriate tool to further prove the occurrence and distribution of hyperforin in mouse brain.

Determination of 11-keto-boswellic acid in human plasma.

A sensitive, specific, accurate, fast and reproducible GC/MS-method for the quantitative determination of 11-keto-boswellic acid in human plasma using 18alpha-glycyrrhetinic acid as the internal standard was developed and validated. 11-Keto-boswellic acid and the internal standard were separated from acidified plasma by liquid/liquid extraction. The extracted samples were methylated and analyzed by GC/MS in the negative ion chemical ionization mode (NICI) and selected ion monitoring (SIM). The total run time was 8 min between injections. The assay described in this paper demonstrates a validated lower limit of quantification of 0.0100 microg/ml using 1 ml of plasma. The calibration curves are linear in the measured range between 10.0 and 2000 ng/ml plasma. The overall precision (expressed as CV) and accuracy (expressed as bias) for all concentrations of quality controls and standards is better than 15%. No indications were found for possible instabilities of 11-keto-boswellic acid in plasma, in whole blood, in the extraction solvent or after repeated thawing/freezing cycles. The recovery of the extraction method is calculated as 84%. The assay was applied successfully to determine the plasma level of 11-keto-boswellic acid in a clinical pilot study.

Formulation-dependent food effects demonstrated for nifedipine modified-release preparations marketed in the European Union.

The objective of this study was a comparative investigation of the influence of concomitant food intake on the bioavailability of two nifedipine-containing controlled-release formulations. Adalat OROS and CORAL were compared in a randomised, non-blind, four-way crossover design in 24 healthy, male subjects after single dose administration following a high fat American breakfast or an overnight fast of 12 h, respectively. Plasma samples were withdrawn until 48 h post-dose. In the fasted state, the bioavailability (AUC and C(max) values) was lower for CORAL than for Adalat OROS. Under fed conditions, differences in bioavailability between both products were markedly increased. With respect to the therapeutic use of both products, the most important finding was the significant dose-dumping effect observed after fed administration of CORAL, resulting in nifedipine plasma concentrations of nearly three- to four-fold in 11 of 24 volunteers. The mean ratio of C(max) was 235% comparing CORAL with Adalat OROS under these conditions. The formulation-dependent food interaction observed in this study may be therapeutically relevant, especially in the case of changing administration conditions or switching from one product to the other.