Comparative in vitro dissolution studies of fixed-dose combination formulations: analgesic tablets of acetaminophen/caffeine

A simple and rapid UV derivative method with zero-crossing determinations was developed for estimation of acetaminophen (ACE) and caffeine (CAF) in fixed-dose combination formulations. The first-derivative of standard solutions of both drugs were used and ACE and CAF were quantified at 273.0 and 216.5 nm, respectively. The method was validated, and it was applied to dissolution studies with the USP Apparatus 2 and flow-through cell (USP Apparatus 4). Dissolution profiles comparisons (generic vs reference) were carried out with model-independent and model-dependent approaches. Mean dissolution time and dissolution efficiency were calculated and significant differences, in almost all calculated parameters, were found (p<0.05). Weibull, logistic, Gompertz, and Probit models were used to fit dissolution data and Probit was the best-fit model that describes the in vitro dissolution performance of ACE and CAF. Using t50% data, derived from this fit, dissolution profiles of ACE in USP Apparatus 2 were significant different (p<0.05). The proposed UV derivative method generates reliable information that can be compared with published results. Dissolution studies of fixed-dose combination formulations are important because quality of generic drug products depends on quality of references. It is essential to maintain a post-marketing evaluation of formulations with analgesic drugs mixed with CAF to offer the population high quality medicines.

Development and Study of Semi-Solid Preparations Containing the Model Substance Corticotropin (ACTH): Convenience Application in Neurodegenerative Diseases

Corticotropin (ACTH, previously an adrenocorticotropic hormone) is used in the diagnosis and treatment of pituitary gland disorders, adrenal cortex disorders, and other diseases, including autoimmune polymyositis, systemic lupus erythematosus, rheumatoid arthritis, Crohn’s disease, and ulcerative colitis. So far, the ointment dosage form containing ACTH for use on the skin is unknown. Therefore, it seems appropriate to develop a semi-solid formulation with corticotropin. Emulsion ointments were prepared using an Unguator based on the cream base Lekobaza® containing corticotropin in different concentrations, and then the physical and chemical parameters of the ointment formulations, such as pH, spreadability, rheological properties, and texture analysis, were evaluated. In addition, a USP apparatus 2 with enhancer cells was utilized to study the in vitro drug release characteristics of the selected formulations. All the ointments obtained were characterized by good spreadability and viscosity. An analysis of the ointment texture was performed and the dependence of the tested parameters on the ACTH content in the ointment was demonstrated. Examination of the structure of the ointment showed that a high concentration of ACTH increases the hardness and adhesiveness of the ointment. In turn, it adversely affects the cohesiveness and elasticity of the ointments tested. The results of the release study showed that ACTH is released the fastest from the formulation with the lowest concentration, while the slowest from the ointment with the highest concentration of ACTH.

Dissolution Method Development and Validation for Estimation of Noscapine Tablets

A dissolution method was developed and UV spectrophotometry was developed for the evaluation of the dissolution of tablets containing 15 mg Noscapine .The dissolution medium 0.1 N HCl was found suitable to ensure sink conditions. USP Apparatus 2, 900 mL dissolution medium 45 minutes and 100 RPM were fixed. Dissolution profiles were generated at 10, 15, 20, 30; 45 min. Dissolution samples were analyzed with UV spectrophotometer at 213 nm. The UV method for determination of tablet was developed and validated. The method presented linearity (R2 = 0.999) in the concentration range of 1–9 μg/mL. The recoveries were good, ranging from 97.18% to 101.45%. The intraday and Interday precision results were 0.54% and 0.78% RSD, respectively. The developed dissolution test is adequate for its purpose and can be applied for the quality control of tablets. Keywords: Dissolution test; Noscapine; Tablets; UV Spectrophotometry method

Evaluation of linagliptin dissolution from tablets using HPLC and UV methods

Linagliptin (LGT) is used to reduce glucose blood levels in patients with type 2 Diabetes mellitus. The proposed conditions for a biowaiver guide can be applied due to high solubility of linagliptin in aqueous media. The aim of the present study was to develop and validate a dissolution test for 5 mg linagliptin coated tablets. After diverse dissolution procedure evaluation, the selected method was achieved using USP apparatus 1 (basket) at 75 rpm and 900 mL of citrate buffer pH 3.5 as dissolution medium. The conditions proposed by biowaiver guide were also applied to this drug, using USP apparatus 2 (paddle) and 900 mL of 0.1 M HCl, pH 4.5 acetate buffer and pH 6.8 phosphate buffer as dissolution medium. HPLC and UV spectrophotometry were used to LGT quantitation and validated for this purpose. The chromatographic and spectrophotometric methods in the dissolution context proved to be linear in 0.5 – 20.0 μg.mL-1 range, precise with RSD values less than 1.0 % and 2.0%, respectively, and accurate (mean recovery 100.29 % and 100.59%). The parameters such as specificity, linearity, accuracy, precision and robustness were according to international guidelines for both methods HPLC and UV. Dissolved linagliptin results were compared using the Student’s t-test and the data found were not significant different (P=0.068). In most dissolution conditions evaluated, LGT presented more than 85% drug dissolved from the tablets in fifteen minutes. The proposed methods can be applied for quality control of this gliptin. According to the results, linagliptin may be a biowaiver candidate.

Dissolution Test for Mianserin Hydrochloride in Tablets

A dissolution test for mianserin hydrochloride in coated tablets containing 30 mg was developed and validated using a fast ultraviolet spectrophotometric method. The appropriate conditions were determinate after testing sink conditions, agitation spped and dissolution medium. The sink conditions tested showed that mianserin hydrochloride was soluble in 0.01 and 0.1 M hydrochloric acid (HCl), acetate buffer pH 4.1 and 5.0 and phosphate buffer pH 6.8. Then, dissolution tests were performed to investigate the drug release in each medium. Optimal conditions to carry out the dissolution test were 900 mL 0.1 M HCl and USP apparatus 2 (paddle) at 50 rpm stirring speed. The quantification method was also adapted and validated. The UV method showed specificity, linearity, precision and accuracy. The in vitro dissolution test can be used to evaluate the drug release profile and the data was used as an aid to establish a possible correlation with in vivo data.

IN VITRO EQUIVALENCE STUDY OF DIFFERENT DOSES OF CARBAMAZEPINE REFERENCE TABLETS USING USP APPARATUSES 2 AND 4

Objective: To perform an in vitro equivalence study of two doses of carbamazepine reference tablets sold in the local market under hydrodynamic conditions of USP Apparatus 4, a dissolution apparatus that better simulates the human gastrointestinal tract. Results were compared with dissolution official conditions using USP Apparatus 2. Methods: Dissolution profiles of both formulations were carried out with an automated USP Apparatus 2 at 75 rpm and 900 ml of dissolution medium. USP Apparatus 4 with laminar flow at 16 ml/min and 22.6 mm cells were used. 1% lauryl sulfate aqueous solution at 37.0±0.5 °C was used as dissolution medium. Spectrophotometric determination of drug at 285 nm was carried out during 60 min. Dissolution profiles were compared with model-independent and-dependent approaches. Results: When comparing dissolution profiles of low vs. high dose similar profiles were found (f2>50) in each dissolution apparatus, however, when the same dose was compared, USP 2 vs. USP 4, opposite results were obtained. Comparison of mean dissolution time and dissolution efficiency data corroborates these results. Weibull function was the best mathematical model that described the in vitro dissolution performance of carbamazepine. No significant differences were found in Td values (low vs. high dose) but opposite results were also found with USP 2 vs. USP 4. Conclusion: Equivalent dissolution performance of two doses of carbamazepine reference tablets were found in each USP dissolution apparatus. The main problem identified in this comparative study is the low dissolution rate and extent found with USP Apparatus 4. More research on this field is necessary for all available doses of reference drug products since the quality of generic formulations depends on the quality of references.

DISSOLUTION BEHAVIOR OF CARBAMAZEPINE SUSPENSIONS USING THE USP DISSOLUTION APPARATUS 2 AND THE FLOW-THROUGH CELL METHOD WITH SIMULATED GI FLUIDS

Objective: To characterize the dissolution behaviour of carbamazepine generic suspensions using the USP Dissolution Apparatus 2 and the flow-through cell method with simulated gastrointestinal fluids as dissolution media.Methods: Tegretol® suspension and two generic formulations were tested. Dissolution studies were performed using the USP Apparatus 2 (75 rpm and 900 ml of dissolution medium) and the flow-through cell method (laminar flow at 16 ml/min). Simulated gastric fluid (SGF) (with and without pepsin) and simulated intestinal fluid (SIF) (without pancreatin) at 37.0±0.5 °C, was used as dissolution media. The quantity of dissolved carbamazepine was determined at 5 min intervals until reaching 60 min, at 285 nm. Percentage dissolved at 60 min, mean dissolution time, dissolution efficiency values (model-independent parameters), as well as t50% and t63.2% were calculated (model-dependent parameters). Values for all parameters were compared between the reference and generic formulations using one-way analysis of variance (ANOVA) following a Dunnett’s multiple comparison test. Dissolution data were also fitted to different fit models.Results: Since the first sampling time, the reference product had reached 100% of drug dissolved, which was determined using USP Apparatus 2. Nevertheless, significant differences in the three model-independent parameters of generic products were found (*P<0.05). Dissolution data obtained with the paddle apparatus were fitted to different kinetic equations; however, using the flow-through cell method and SIF without pancreatin, the three drug products were fitted to the same kinetic model (Gompertz). With ANOVA-based comparisons and the flow-through cell method, significant differences were found in dissolution data of generic product A versus reference at all sampling times (*P<0.05). The flow-through cell method and SGF with pepsin were the best options to discriminate among dissolution profiles.Conclusion: The flow-through cell method seems to be an adequate dissolution apparatus to characterize in vitrodissolution performance of Class II drugs manufactured as suspensions. For carbamazepine suspensions, SGF and laminar flow at 16 ml/min were the most appropriate conditions to discriminate among generic formulations. Given the physicochemical characteristics of carbamazepine and the environment in which the drug products were tested, these differences could be of clinical relevance.

COMPARISON OF THE USP APPARATUS 2 AND 4 FOR TESTING THE IN VITRO RELEASE PERFORMANCE OF IBUPROFEN GENERIC SUSPENSIONS

Objective: The aim of this study was the comparison of the in vitro release performance of ibuprofen generic suspensions and reference, based on the hydrodynamic environment generated by the flow-through cell method (USP Apparatus 4). Results were compared with those obtained by the use of the USP Apparatus 2.Methods: The Advil® suspension (2 g/100 ml) and two generic formulations with the same dose were tested. Dissolution studies were carried out using a USP Apparatus 4 Sotax CE6 with 22.6 mm cells, laminar flow at 16 ml/min, and pH 7.2 phosphate buffer at 37.0±0.5 °C as dissolution medium. Ibuprofen was quantified spectrophotometrically at 222 nm. The in vitro release of the three drug products were studied using the USP Apparatus 2. The dissolution profiles of generic products were compared with the reference by model-independent, model-dependent, and analysis of variance (ANOVA)-based comparisons.Results: The dissolution profile of the generic product A was similar to the dissolution profile of reference, only with the use of the USP Apparatus 4. The f2 similarity factor was>50 and no significant differences were found with dissolution efficiency data (*P>0.05). Similar results were found with the comparison of t50% and t63.2% values. Similar dissolution profiles between generic product A and reference were also found with ANOVA-based comparisons.Conclusion: The flow-through cell method was adequate for study the in vitro release of ibuprofen suspensions. It is necessary to evaluate the in vivoperformance of the drug products used in order to estimate the predictability of the proposed methodology.

Formulation and In vitro Evaluation of Oral Floating Tablets of Salbutamol Sulphate: Comparison with Effervescent Tablets

The aim of this research was to develop and evaluate gastric floating tablets of salbutamol sulphate. The oral delivery of anti-asthmatic salbutamol sulphate tablets were facilitated by preparing floating dosage form which could increase its absorption in the stomach by increasing the gastric residence time of the drug. Floating tablets were formulated by using different polymers like carbopol, xanthan gum, HPMC-K4 MCR and HPMC- K100 MCR with different proportions. A comparative study of normal effervescent tablets of salbutamol sulphate had also been done. The prepared tablets were evaluated for all their physicochemical properties and in vitro buoyancy study. In vitro dissolution studies of the formulations were done in pH 6.8 phosphate buffer using USP apparatus 2 (paddle method) at 50 rpm. Percent drug release of the formulations (F-1 to F-11) was from 87.34%- 99.12% after 12 hours. From the results, F-11 was selected as an optimized formulation based on 12 h drug release which showed minimal floating lag time and maximum floating time. On the other hand, 100% drug was released within 2 hours from the F-12 of effervescent salbutamol sulphate tablets in which polymer was absent while gas generating sodium bicarbonate and citric acid were present. The results of the study were consistent and may encourage formulating similar dosage form with other drugs.Dhaka Univ. J. Pharm. Sci. 15(2): 203-208, 2016 (December)