Venlafaxine Hydrochloride Controlled Release Bilayer Tablets: Optimization Of Formulation Variable By Using Dyspnea On Exertion

The current research work was to develop bilayer tablet of venlafaxine hydrochloride to increase drug efficacy for efficient treatment of depression. The satisfactory result of treatment can be achieved upon the maintenance of drug concentration within an effective level in the body, so a uniform and constant drug supply are desirable. An immediate layer of venlafaxine HCl was formulated using super disintegrants, i.e., croscarmellose sodium (CCS) and sodium starch glycolate (SSG); tablet compact by direct compression. HPMC K100M and ethylcellulose (EC) were utilized as release retarding polymers in sustained release layer by wet granulation technique with the help of PVP K30 in IPA solution (10%) as a granulating agent. Full 32 factorial designs were used to find out the optimum quantity of release retardant polymers. Bilayer tablet was evaluated for various parameters, i.e. hardness, friability, weight variation, % drug content, disintegration time (IR layer), and % drug release study. Statically, an analysis was carried out using factor X1 (HPMC K100M) and X2 (EC) for dependent variable % drug release at 8, 12, and 20 hours. A formulation was optimized and a formulation containing 305.36 mg of HPMC K100M and 54.03 mg of ethyl cellulose. Optimized formulation show 47.12 ± 2.1, 59.89 ± 2.2, and 89.06 ± 2.3 drug release at 8, 12, and 20 hours, respectively, which is almost similar to theoretical dose calculation with similarity factor f2 97, 99, and 98%, respectively. Bilayer tablet formulation was observed to be stable and fulfilled all compendia specifications.

A fast adaptive active contour model based on local gray difference for parotid duct / 南方医科大学学报

OBJECTIVE@#To establish a fast adaptive active contour model based on local gray difference for parotid duct image segmentation.@*METHODS@#On the basis of the LBF model, we added the mean difference of the local gray scale inside and outside the contour as the energy term of the driving evolution curve, and the local gray-scale variance difference was used to replace and as the control term of the energy parameter value. Two local similarity factors of different neighborhood sizes were introduced to correct the effects of image gray unevenness and boundary blur to improve the segmentation efficiency.@*RESULTS@#During image segmentation, this algorithm allowed for adaptive adjustment of the evolution direction, velocity and the energy weight of the internal and external regions according to the difference of gray mean and variance between the internal and external regions. This algorithm was also capable of detecting the actual boundary in a complex gradient boundary region, thus enabling the evolution curve to approach the target boundary quickly and accurately.@*CONCLUSIONS@#The proposed algorithm is superior to the existing segmentation algorithms and allows fast and accurate segmentation of the parotid duct with well-preserved image details.

Similarity Evaluation of Dissolution Curves of Self-made and Original Telmisartan /Hydrochlorothiazide Tablets by the f2 Factor Method / 中国药学杂志

OBJECTIVE: To explore the similarity of the dissolution curves of self-made and original telmisartan /hydrochlorothiazide tablets and provide basis for the prescription and process screening of self-made preparation and the quality similarity evaluation with original preparation. METHODS: The dissolution curves of telmisartan and hydrochlorothiazide from self-made and original preparations in four different dissolution media were determined using HPLC. The HPLC method was performed on Welch Ultimate XB-C8 column (4.6 mm × 250 mm, 5 μm) with mobile phase A consisting of ammonium dihydrogen phosphate solution (2.0 g ammonium dihydrogen phosphate was dissolved in 1 L water then adjusted to pH 3.0 with phosphoric acid) and mobile phase B consisting of acetonitrile- methanol (50:50) at a flow rate of 1.2 mL•min-1. The detection wavelength was set at 270 nm. The injection volume was 20 μL. Then f2 factor method was used to evaluate the similarity. RESULTS: The dissolution curves of self-made and original preparations of telmisartan /hydrochlorothiazide tablets in different dissolution media showed similarity, with the f2 factor ≥50 or the dissolution rate within 15 min≥85%. CONCLUSION: The dissolution behaviors of self-made and original telmisartan /hydrochlorothiazide tablets are basically similar, which indicates that the prescription and technology of self-made preparation are reasonable and feasible.

Determination of the Dissolution Curves of Albendazole Tablets / 中国药学杂志

OBJECTIVE: To establish a determination method of the dissolution curves of albendazole tablets with differentiation ability and investigate the similarity of dissolution curves in vitro between reference preparation and generic preparations.METHODS: Paddle method was adopted with rotation speed of 50 r•min-1 and the dissolution medium volume was 900 mL. The dissolution media were pH 1.2 hydrochloric acid solution and water. The similarity factor (f2) method was used to evaluate the comparability of dissolution curves.RESULTS: The three established dissolution curves had good distinguishing ability. As shown by the similarity factor (f2), the generic preparation from manufacture A was similar to the reference preparation, while those from the manufacture B and C were not similar.CONCLUSION: The study provides the experimental basis for the consistency evaluation of the dissolution curves of abendazole tablets.

Estudio comparativo de la calidad biofarmacéutica de marcas comerciales y multifuente de tabletas de ibuprofeno en el mercado colombiano / Comparative study of the biopharmaceutical quality of commercial brands and multisource of ibuprofen tablets in the Colombian market

RESUMEN Los medicamentos de mayor consumo en el mundo son los analgésicos antiinflamatorios no esteroideos (AINEs), debido a su capacidad para aliviar el dolor, condición común a muchas patologías. Uno de los AINEs de gran utilización en Colombia es el ibuprofeno. Con el fin de evaluar la conformidad de los productos y determinar su equivalencia biofarmacéutica, se adquirieron y evaluaron un total de 10 productos comerciales. Estos se compraron en establecimientos comerciales de cuatro de las principales ciudades del país: Cartagena, Barranquilla, Bogotá y Cali. Para ello, se evaluaron las características físicas, químicas y biofarmacéuticas de las tabletas, tales como variación de peso, dureza, desintegración, prueba de disolución, perfil de disolución, eficiencia de la disolución y valoración de principio activo a partir de metodologías validadas. Los ensayos farmacopeicos se evaluaron según lo establecido en la USP 39. Los resultados permitieron establecer que todos los productos evaluados cumplieron con las especificaciones de la Farmacopea, con respecto a contenido de ingrediente activo y prueba de disolución. En cuanto al comportamiento biofarmacéutico, pese a que todas las marcas cumplen con las especificaciones farmacopeicas, solo tres de las 10 marcas evaluadas son biofarmacéuticamente equivalentes con el innovador. Los resultados de este trabajo permiten proponer a la comunidad científica la determinación de la equivalencia biofarmacéutica como elemento de apoyo en la toma de decisiones de compra en el servicio farmacéutico.

SUMMARY The most widely used drugs in the world are non-steroidal anti-inflammatory analgesics (NSAIDs), because of their ability to relieve pain, a condition common to many pathologies. One of the widely used NSAIDs in Colombia is Ibuprofen. To assess the conformity of products and determine their biopharmaceutical equivalence, a total of 10 commercial products were purchased and evaluated. These were bought in commercial establishments of four of the main cities of the country: Cartagena, Barranquilla, Bogota and Cali. For this purpose, the physical, chemical and biopharmaceutical characteristics of the tablets were evaluated, such as weight variation, hardness, disintegration, dissolution test, dissolution profile, dissolution efficiency and active ingredient titration from validated methodologies. The pharma-copoeial tests were evaluated according to USP 39. The results allowed to establish that all evaluated products met the specifications of the pharmacopoeia with respect to content of active ingredient and test of dissolution. Regarding biopharmaceutical behavior, although all brands comply with pharmacopoeial specifications, only three of the ten brands evaluated are biopharmaceutically equivalent to the innovator. The results of this work allow proposing to the scientific community, the determination of biopharmaceutical equivalence as an element of support in making purchasing decisions in the pharmaceutical service.

Similarity Comparison of the Dissolution Curve of Risperidone Oral Soluble Films in Various Dissolution Media / 中国药师

Objective: To study the effect of different dissolution media on the dissolution curve of risperidone oral soluble films to provide reference for the quality evaluation of the preparation.

Study on in vitro release consistency between self-prepared Torasemide Sustained-Release Tablet and original preparation / 药物评价研究

Objective To establish a method for determining the dissolution oftorasemide sustained-release tablet in vitro and study the methodology of the determination.The consistency of the in vitro release behavior between self-prepared torasemide sustained-release tablet and original preparation were evaluated by constructed method.Methods HPLC method was applied to detect the cumulative release percentage of self-prepared torasemide sustained-release tablet and original preparation in five kinds of release media (water,0.1 mol/L hydrochloric acid solution,pH 4.5 acetate buffer,pH 6.8 phosphate buffer,and 0.1 mol/L hydrochloric acid solution turn to pH 6.8 phosphate buffer).Similarity factor (f2) was used to evaluate the similarity of release curves.Results There was a good linear relationship between the quality concentration of torasemide and peak area in the range of 1.0-12.0 μg/mL (r =0.9995).Results of precision and stability tests were good,and the RSDs for probational liquid were all lower than 2.0％.The average recovery of accuracy test was 100.04％,and RSD was 0.54％ (n =12).The homogeneity of within group of self-prepared preparation met the technical requirement,RSDs of each sampling points in six Dissolution Vessels were lower than 10.0％.The f2 factors of self-prepared torasemide sustained-release tablet and original preparation were 72,60,77,66,and 60 in five kinds of release media.Conclusion The method in the paper is suitable for the release test of torasemide,meanwhile,the self-prepared tablet shows consistent in vitro release behavior with that of the original preparation.

Similarity Evaluation of the Dissolution Curves between Generic and Original Metoprolol Tartrate Tablets / 中国药房

OBJECTIVE:To establish the method for dissolution determination of Metoprolol tartrate tablets,and to evaluate the similarity of dissolution curves of generics and original drugs. METHODS:The paddle method was adopted with rotational the speed of 50 r/min,using pH 1.2 hydrochloric acid solution,pH 4.5 acetate buffer solution and pH 6.8 phosphate buffer solution as dissolution media. Fiber-optical drug dissolution real-time measurement instrument was used to determine the dissolution curves of generic and original Metoprolol tartrate tablets with optical distance of 10 mm. Similarity factor (f2) method was used to evaluate its similarity. RESULTS:In 3 dissolution mediums,the f2 of generic and original Metoprolon tartrate tablets were 80.5,66.8, 69.4,respectively,which indicated that the dissolution curves showed similarity. CONCLUSIONS:Established real-time dissolution process analysis method is suitabe for the dissolution determination of Metoprolol tartrate tablets. Generic and eriginal show the sim-ilarity in dissolation behavier,so they have good consistency in quality.

Effects of Particle Size of Ticagrelor Crude Drug on in vitro Dissolution Behavior of Ticagrelor Tablets / 中国药房

OBJECTIVE:To study the effects of particle size of ticagrelor crude drug on in vitro dissolution behavior of Ticagre-lor tablets. METHODS:Ticagrelor crude drug and different particle size of ticagrelor powder A,B,C,D,E after smashing for dif-ferent time(15,30,40,60 s)were used to prepare the tablet by wet granulation method. Accumulative in vitro dissolution rate of prepared tablets within 60 min were determined by UV spectrophotometry at 300 nm(using 0.2% tween as medium,paddle meth-od). Using original tablet as reference preparation,the similarity factor(f2)method was used to compare the similarity of dissolu-tion behavior between 5 prepared tablets and original tablet. RESULTS:d(0.9)of powder A,B,C,D,E were 69.181,40.778, 24.805,12.611,3.083 μm,respectively. The corresponding f2 were 27.77,36.79,50.06,67.68,79.99. CONCLUSIONS:The par-ticle size of ticagrelor crude drug is much smaller,and the dissolution behavior of prepared tablet is closer to that of original tablet. The in vitro dissolution rate of Ticagrelor tablets is improved remarkably by micronization technology. In order to produce Ticagre-lor tablets with the same bioavailability as original tablet,particle size of ticagrelor crude drug powder should be controlled with d(0.9)≤20μm.

Similarity Evaluation of the Dissolution Curves of Generic and Original Preparation of Losartan Potassium Tablets / 中国药房

OBJECTIVE:To evaluate the dissolution curves similarity of generic and original preparation of Losartan potassium tablets,and to provide reference for improving quality evaluation of the preparation.METHODS:Using hydrochloric acid solution (pH 3.0),phosphate buffer solution(pH 4.5),phosphate buffer solution (pH 6.8) and water as medium,paddle method was adopted for dissolution test with dissolution medium volume of 900 mL and rotation speed of 50 r/min.UV-visible spectrophotometry was adopted to determine accumulative dissolution of generic and original preparation of Losartan potassium tablets with the detection wavelength of 256 um.The similarity of dissolution curves were evaluated by calculating similarity factor(f2).RESULTS:The linear range of losartan potassium was 12.11-35.96 μg/mL (r≥0.999 7).RSDs of precision,stability and reproducibility tests were all lower than 5.0％.The recoveries of 4 dissolution media were 98.66％-100.84％ (RSD=0.77％,n=9),98.91％-100.59％ (RSD=0.49％,n=9),98.33％-101.39％ (RSD=0.85％,n=9),99.46％-101.32％ (RSD=0.55％,n=9).In 4 dissolution media,f2 of the dissolution curves of 3 batches of generic and original preparation of Losartan potassium tablets were all higher than 70.CONCLUSIONS:The dissolution curves of self-made and original preparation of Losartan potassium tablets show good similarity.

In-vitro bioequivalence, physicochemical and economic benefits study for marketed innovator and generic ciprofloxacin hydrochloride tablets in Saudi Arabia.

The objective of the present study was to compare and evaluate the economic benefits and in-vitro bioequivalence of different marketed generic ciprofloxacin tablets against the innovator tablet formulation that are present in the local market of Saudi Arabia. The comparative bioequivalence and physicochemical study of five ciprofloxacin marketed tablets were performed through the assessment of the uniformity of weight, hardness, disintegration, dissolution, and content assay of the products. In order to compare the dissolution profiles of all generic tablet formulations and the innovator, a model independent approach of similarity factor (f2) and difference factor (f1) was employed in the in vitro dissolution studies. Deviations were noted in two generic products, these deviations caused significant differences in disintegration time and dissolution profile in only one of the generic products. All tested generic products passed USP monograph dissolution testing except one product which failed to pass both similarity factor (f2) and difference factor (f1) tests required by FDA bioequivalence testing. The majority of generic products in Saudi Arabia which had lower prices showed comparable quality to innovator.

Comparación de los perfiles de disolución de comprimidos de lamotrigina de 100mg comercializados en Paraguay / Comparison of the dissolution profiles of tablets of lamotrigine 100mg traded in Paraguay

Objetivo: evaluar los perfiles de disolución decomprimidos de Lamotrigina 100mg (Test) con laReferencia (Lamictal®) comercializados en Paraguay.Material y Métodos: Se utilizaron comprimidosde Lamotrigina de 100mg comercializados enParaguay. Se determinaron los perfiles de disoluciónde los productos Test y Referencia, en los tresmedios de disolución recomendados (pHs 1,2 ; 4,5y 6,8). El método analítico se basó en HPLC condetector PDA a 277nm, usando una PhenomenexLuna C18 a 40ºC, con fase móvil de buffer fosfatode sodio 0.05M pH4.0-acetonitrilo (80:20), flujode 1.3mL/min y tiempo de retención de 5 min.Resultados: Los perfiles de disolución del productoTest de Lamotrigina 100mg, fueron similaresen los diferentes pHs al producto de Referencia,liberando más del 85% a los 15 minutos en los 3medios de disolución, no siendo necesaria la comparacióncon el factor f2.Conclusión: Los perfiles de disolución de los comprimidosde Lamotrigina de 100mg Test muestranun comportamiento in vitro semejante al productode Referencia, lo que sugiere que su comportamientoin vivo podría ser también semejante.

Objectives: to evaluate the dissolution profiles ofLamotrigine tablets of 100 mg (Test) and Reference(Lamictal®) marketed in Paraguay.Material and Methods: Tablets of Lamotrigine100 mg marketed in Paraguay were used. Dissolutionprofiles of the Test and Reference productswere determined in the three recommended dissolutionmedia (pH 1.2; 4.5 and 6.8). The HPLCmethod used consisted of a Phenomenex Luna C18column, with mobile phase of 0.05M sodium phosphatebuffer pH4.0-acetonitrile (80:20), flow rateof 1.3mL / min and retention time of 5 min. Thecolumn compartment was kept at 40ºC, and thewavelength detection was 277 nm.Results: The dissolution profiles of the Test productof Lamotrigine 100mg, showed similar behavior tothe Reference product at the three different pHs,releasing more than 85% in 15 minutes in the threemedia dissolution. No calculation using the similarityfactor f2 was needed.Conclusion: Dissolution profiles of the two formulationsof Lamotrigine 100mg were similar in thedifferent pH dissolution media, thus a similar invivo behavior could be expected.

Comparability evaluation of dissolution curve of esomeprazole magnesium enteric tablets / 国际药学研究杂志

Objective To evaluate the similarity of dissolution behavior in vitro of self-made and reference listed drug(RLD) of esomeprazole magnesium enteric tablets. Methods The dissolution test method and HPLC method were established according to Chinese pharmacopoeia. The HPLC method was validated according to ICH guidance. The dissolution behavior of the 3 batches of the self-made drug and RLD were compared in dissolution medium of pH 1.2 HCl solutuion,pH 4.5 phosphate buffer,pH 6.8 phosphate buffer,pH 1.2 HCl solutuion(2 h)and pH 6.0 phosphate buffer,pH 1.2 HCl solutuion(2 h)and pH 6.8 phosphate buffer,and puri?fied water with different rotation rates. Results The HPLC validation results for linearity,repeatability,recovery,etc. all met the re?quirement. The similarity factors F2 between the self-made drug and RLD were greater than 50 in different dissolution mediums. Con?clusion The dissolution behaviors of the self-made drug and RLD are similar.

Preparation of self-microemulsifying drug delivery system and similarity analysis on dissolution behavior of ginkgolides components / 中草药

Objective: Optimization of ginkgolides components (GC) self-microemulsifying drug delivery system (SMDDS) (GC-SMDDS) and similarity analysis on each drug release. Methods: Using equilibrium solubility to screen the oil phase, emulsifier, and co-emulsifier; Taking appearance, the proportion of microemulsion particle size, Zeta potential, surfactants and co-surfactants, and surfactant mixing ratio of the oil phase as study factors, pseudo-ternary phase diagrams were used to screen GC-SMDDS process. SMEDDS of drug loading, particle size distribution, Zeta potential, and stability were evaluated. With the aid of the similarity factor and the curve linear regression slope analysis, the similarity between the composition of the component and the rate and extent of drug release was analyzed. Results: Optimal prescription of polyoxyethylene and polyethylene glycol 200 mass ratio of 4:1, ethoxylates and polyethylene glycol quality and bitterness total mass of 200 capric triglycerides ratio of 9:1, drug content of 100 mg/g. Particle size under 40 nm, ginkgolides 48 h internal components from microemulsion to room temperature, high temperature, and low temperature stability is good. The release quantity achieves the synchronous drug release with the similarity of 96.9%. Conclusion: The SMDDS not only can improve the dissolution of difficult soluble drugs, but also independently regulate the drug release behavior of each component so as to make the drug release maintain good consistency.

Comparability evaluation of dissolution curve of esomeprazole magnesium enteric tablets / 国际药学研究杂志

Objective To evaluate the similarity of dissolution behavior in vitro of self-made and reference listed drug (RLD) of esomeprazole magnesium enteric tablets. Methods The dissolution test method and HPLC method were established according to Chinese pharmacopoeia. The HPLC method was validated according to ICH guidance. The dissolution behavior of the 3 batches of the self-made drug and RLD were compared in dissolution medium of pH 1.2 HCl solutuion, pH 4.5 phosphate buffer, pH 6.8 phosphate buffer, pH 1.2 HCl solutuion (2 h) and pH 6.0 phosphate buffer, pH 1.2 HCl solutuion (2 h) and pH 6.8 phosphate buffer, and purified water with different rotation rates. Results The HPLC validation results for linearity, repeatability, recovery, etc. all met the requirement. The similarity factors F2 between the self-made drug and RLD were greater than 50 in different dissolution mediums. Conclusion The dissolution behaviors of the self-made drug and RLD are similar.

Preparation Process of Xuangui Zhitong Dispersible Tablets / 中国药房

OBJECTIVE:To prepare Xuangui zhitong dispersible tablets and optimize its formulation technology. METHODS:Using disintegration time as index,single factor test was conducted for filler,disintegrating agent,the types and amount of adhe-sives and compression pressure. The amount of mixed disintegrating agent,avicel and gum arabic were optimized by orthogonal test. The tablet quality by optimized formulation was detected,and disintegration time,the content and dissolution rate of tetrahy-dropalmatine were determined;the similarity of in vitro dissolution rate of dispersible tablets and dropping pills were evaluated by similarity factor test. RESULTS:The optimized formulation was composed of 25% MCC as fillers,9% PVPP and 9% L-HPC as mixed disintegrants,85% ethanol solution as adhesives,micro-silica gel 2%,compression pressure of 3.0 kg/cm2. The average dis-integration time was 1.22 min,and the content of tetrahydropalmatine was 1.097 mg/g. The accumulative dissolution rate was more than 80% at 10 min and more than 90% at 15 min. The similarity factor f2 of dissolution curve was 62,using dropping pills as ref-erence preparation. CONCLUSIONS:Xuangui zhitong dispersible tablet had a rapid disintegration and the behavior of dissolution is similar to Xuangui zhitong dropping pills.

Consistency Evaluation of the Dissolution of Generic and Original Preparations of Dronedarone Hydrochlo-ride Tablet / 中国药房

OBJECTIVE:To establish a method for the dissolution determination of Dronedarone hydrochloride tablet,and eval-uate the quality consistency of its generic and original preparations. METHODS:UV spectrometry was performed on the column of 288 nm,dissolution media of Phosphate buffer solution (pH4.5),0.1 mol/L Hydrochloric acid solution [adding into 0.5% sodium dodecyl sulfate(SDS)],Phosphate buffer solution [pH6.8,adding into 0.5%SDS] and water,volume of dissolution medium was 1 000 ml,rotation speed was 75 r/min,the dissolution of generic and original preparations of Dronedarone hydrochloride tablet was detected,and the similarity of dissolution curve was evaluated by calculating the similarity factor (f2). RESULTS:The linear range of dronedarone hydrochloride was 2.147-25.764 μg/ml;RSDs of precision,stability and reproducibility tests were lower than 2.0%;recoveries 4 dissolution media were 99.53%-101.05%(RSD=0.48%,n=9),98.95%-100.05%(RSD=0.39%,n=9), 99.54%-100.20%(RSD=0.24%,n=9)and 98.54%-100.06%(RSD=0.44%,n=9). In the 4 dissolution media,f2 of the dissolu-tion curve of 3 batches of generic and original preparations of Dronedarone hydrochloride tablet was 56,60,63,68,68,52,59, 67,65,68,76,62,respectively. CONCLUSIONS:The method is suitable for the dissolution determination of Dronedarone hydro-chloride tablet;meanwhile,the in vitro dissolution curves of generic and original preparations of Dronedarone hydrochloride tablet show similarity,so the quality consistency is good.

Similarity Evaluation of Dissolution Profiles of Self-development and Original Preparation of Solifenacin Suc-cinate Tablet / 中国药房

OBJECTIVE:To explore the similarity of dissolution profiles of self-development and original preparation of Solife-nacin succinate tablet,and provide reference for the prescription and process screening of the former one and the quality similarity evaluation of the latter one. METHODS:The paddle method was adopted with rotational speed of 50 r/min,using water,pH1.2 hy-drochloric acid solution,pH4.0 acetate buffer solution and pH6.8 phosphate buffer solution as dissolution media,HPLC was used to determine the cumulative dissolution of main components of self-development and original preparation of Solifenacin succinate tablet at different time points,dissolution profile was drew,then f2 was used to evaluate its similarity. RESULTS:In the 4 dissolu-tion media,the f2 of both self-development and original preparation of Solifenacin succinate tablet was higher than 50,which indi-cated that the dissolution profiles showed similarity. CONCLUSIONS:The established HPLC is suitable for the dissolution determi-nation of Solifenacin succinate tablet;the dissolution profiles of the self-development and original preparations are basically simi-lar,which indicates the prescription and technology of self-development preparation are feasible.

Similarity evaluation of the dissolution curves of domestic and imported cilnidipine tablets and study on dissolution method with discriminatory power / 中国药学杂志

OBJECTIVE: To study the dissolution behavior of cilnidipine tablets, evaluate the consistency of dissolution behavior between three domestic products and the original tablets, and develop a new dissolution method with discriminatory power for prescription process. METHODS: The dissolution media were hydrochloric acid solution (pH 1.2), acetate buffer (pH 4.0), phosphate buffer (pH 6.8) and water, all containing 0.4% SDS. Using original tablets as the reference preparation, the dissolution curve of the test and reference preparations was compared by the similarity factor method. Apparatus 2 was used for the new method of dissolution test, using 900 mL phosphate buffer with 0.5% SDS (pH 6.8) as the dissolutive medium,at the rate of 75 r·min-1. The dissolution solution was taken at 60 min and analyzed by HPLC. The dissolution limit was set at 70%. RESULTS: For the three domestic pharmaceutical products, only one had consistent dissolution curves in the four dissolution media with the original product from Japanese Ajinomoto Co.. The new method of dissolution test could distinguish the products manufactured by advanced technology from those by process of general level. CONCLUSION: The new dissolution method has discriminatory power for prescription process of insoluble cilnidipine tablets when using phosphate buffer (pH 6.8) as the dissolutive medium, and the quality of the product can be effectively controlled.

Comparative in vitro dissolution of commercially available sustained release nifedipine tablet brands in the Kumasi Metropolis, Ghana.

The aim of this study was to assess the dissolution properties of twelve sustained release (SR) nifedipine tablet brands, including 20 mg and 30 mg innovator brands, for possible generic substitution. The tablet brands were purchased from retail pharmacies in the Kumasi Metropolis, Ghana. The weight uniformity, drug content and in vitro dissolution of the tablets in phosphate buffer pH 6.8 were evaluated. The dissolution data were compared using the similarity (f2) and difference (f1) factors, and the USP acceptance criteria for SR tablets. The kinetics of drug release from the tablets was also evaluated. All the brands passed the weight uniformity test. Nine brands (75 %) passed the drug content test while three brands (25 %) failed. The two innovator nifedipine SR brands passed all the tests undertaken. Comparison of the dissolution data using f1 and f2 showed that all three 30 mg nifedipine SR brands were dissimilar to the innovator brand. Also, two 20 mg nifedipine SR brands (28.6 %) were similar or bioequivalent with the innovator 20 mg brand while five brands (71. 4 %) were dissimilar. Three (75 %) 30 mg and four (50 %) 20 mg nifedipine SR brands exhibited appropriate drug release profiles based on the USP acceptance criteria. Drug release from the twelve tablet brands mostly followed the Higuchi kinetic model (58.3 %) followed by the Hixson-Crowell model (16.7 %). Only one brand (N7) exhibited constant drug release kinetics. Results from the study have shown that switching or substituting brands of SR nifedipine for patients should be guided by a critical assessment of the dissolution data using appropriate evaluation techniques.