ABSTRACT
The purpose of the current work was to formulate Verapamil Hydrochloride (VH) sustained release matrix tablets by using natural polymers and comparison with leading national brand Calan SR of Searle Pharmaceuticals. Tragacanth and pectin were used in various concentrations. Pre compression studies i.e. angle of repose, bulk density, tapped density, Carr’s compressibility index and Hausner’s ratio were also performed and found within the Pharmacopoeial limits. Eight formulations (F1-F8) of (VH) were prepared by direct compression method. Post compression studies i.e. Thickness, Hardness, Diameter, Friability and Dissolution studies were conducted. Different kinetic models i.e. zero order, first order, Highuchi model and Korsmeyer Peppas were applied to study release patterns and similarity index was calculated. Dissolution studies were carried out in phosphate buffer of pH 6.8 showed that formulations (F4 and F8) formulated with higher polymers concentration showed comparatively better drug retardation. F5 was the most comparable with the reference product. Verapamil hydrochloride released was observed non-fickian as diffusion following Higuchi model.
ABSTRACT
The purpose of the current work was to formulate Verapamil Hydrochloride (VH) sustained release matrix tablets by using natural polymers and comparison with leading national brand Calan SR of Searle Pharmaceuticals. Tragacanth and pectin were used in various concentrations. Pre compression studies i.e. angle of repose, bulk density, tapped density, Carr’s compressibility index and Hausner’s ratio were also performed and found within the Pharmacopoeial limits. Eight formulations (F1-F8) of (VH) were prepared by direct compression method. Post compression studies i.e. Thickness, Hardness, Diameter, Friability and Dissolution studies were conducted. Different kinetic models i.e. zero order, first order, Highuchi model and Korsmeyer Peppas were applied to study release patterns and similarity index was calculated. Dissolution studies were carried out in phosphate buffer of pH 6.8 showed that formulations (F4 and F8) formulated with higher polymers concentration showed comparatively better drug retardation. F5 was the most comparable with the reference product. Verapamil hydrochloride released was observed non-fickian as diffusion following Higuchi model.
ABSTRACT
Verapamil Hydrochloride is a calcium channel blocking anti-anginal agent. Extensive first pass metabolism, low bioavailability (~20%) and short biological half life (4.8 hrs) altogether makes it an ideal candidate for transdermal drug delivery. The objectives of this study were to develop matrix-type transdermal patches of verapamil hydrochloride (VPL) with combinations of hydroxypropyl methyl cellulose (HPMC) and hydroxy propyl cellulose (HPC) as matrix polymers and to investigate the influence of oleic acid (OA) on in vitro permeation of VPL through rat skin. The permeation studies were performed using Franz-type diffusion cells and full-thickness excised abdominal rat skin. The effect of the polymers on the drug release, percentage moisture loss, percentage moisture absorption, folding endurance, and thickness, were investigated.. In vitro release studies showed zero-order release of the drug from all the patches, and the mechanism of release was diffusion mediated. Data was analysed using different release kinetic models. In vitro release profiles showed that from optimized combination the release of the drug was sustained and it extended over a period of 24 hr VPM 006 emerged as the most satisfactory formulation as far as its technological properties were concerned.
ABSTRACT
The interaction between Verapamil Hydrochloride and Magnesium Sulphate (anhydrous) has been studied in an aqueous system at pH 7.4 and 2.4. From spectrophotometric study, it has been found that Verapamil Hydrochloride form 1:1 complex with Magnesium Sulphate (anhydrous). Spectral studies helps to detect the initial complexation between drug and metal. Job’s plot at 7.4 and 2.4 provides same type of information. The Ardon’s spectrophotometric method confirmed the 1:1 complexation and the value of stability constants was calculated using Ardon’s plot. An in vitro study of protein binding of Verapamil Hydrochloride and their 1:1 mixture with Magnesium Sulphate (anhydrous) has been conducted by equilibrium dialysis method at (37 ± 0.5)0C and at pH 7.4. The Scatchard plots were prepared to reveal the number of binding sites and the affinity for protein binding. It has been found that interaction of the drug with Magnesium Sulphate (anhydrous) results into increasing the affinity and increasing the protein binding of Verapamil Hydrochloride.
ABSTRACT
The present study involves preparation and evaluation of floating microspheres of verapamil hydrochloride for improving the drug bioavailability by prolongation of gastric residence time. Cellulose acetate, acrycoat S100 and eudragit S100 microspheres loaded with verapamil hydrochloride were prepared by solvent diffusion-evaporation method. The microspheres had smooth surfaces, with free-flowing and good-packing properties. The yield of the microspheres was up to 70.51 percent and cellulose acetate microspheres entrapped the maximum amount of the drug. Scanning electron microscopy confirmed their hollow structures with sizes in the range 251.80 to 350.75 mm. The prepared microspheres exhibited prolonged drug release and remained buoyant for more than 12 h. Radiographic images of dog stomach revealed that cellulose acetate microspheres loaded with barium sulphate floated on the gastric fluid for about 3.2 h. In vitro release studies demonstrated non-Fickian diffusion of drug from the microspheres.
O presente estudo envolve a preparação e a avaliação de microesferas flutuantes de cloridrato de verapamil para o melhoramento da biodisponibilidade do fármaco por meio do prolongamento do tempo de residência gástrica. Prepararam-se, por meio do método de difusão-evaporação de solvente, microesferas de acetato de celulose, acrycoat S100 e eudragit S100 carregadas com cloridrato de verapamil. As microesferas apresentaram superfícies regulares, com propriedades de fluxo livre e de bom empacotamento. O rendimento das microesferas foi superior a 70,51 por cento e as microesferas de acetato de celulose captaram a quantidade máxima do fármaco. Microscopia eletrônica de varredura confirmou as cavidades em suas estruturas, com tamanhos na faixa de 251,80 a 350,75 mm. As microesferas preparadas apresentaram liberação prolongada do fármaco e permaneceram flutuantes por mais que 12 h. Imagens radiográficas do estômago de cão revelaram que as esferas de acetato de celulose carregadas com sulfato de bário flutuaram no fluido gástrico por, aproximadamente, 3,2 h. Estudos de liberação in vitro demonstraram difusão não-Fickiana dos fármacos das microesferas.
Subject(s)
Stomach/metabolism , Microspheres , Verapamil/pharmacokinetics , Biological Availability , Microscopy, Electron, Scanning/methodsABSTRACT
OBJECTIVE:To study the effect and mechanism of cilostazol in experimental anti-bradyarrhythmia.MET-HODS:Bradyarrhythmia model of mice was induced using verapamil hydrochloride and nicotine,respectively.The electrocardiograms at different time and the heart rates of the model mice after intragastric administration of different dosages of cilostazol were recorded.The in vivo His' bundle electrogram(HBE)recordings in rabbits were obtained after intragastric administration of different dosage of cilostazol for detection of A-H interval and H-V interval,which were compared with control group(normal saline group).RESULTS:Verapamil hydrochloride and nicotine markedly slowed down the heart rates of mice,but cilostazol significantly sped up the heart rates in mice(P
ABSTRACT
Objective To evaluate the in vivo behaviour of the pulsed tablet in six scintigraphic studies.Methods The lag time and the anatomical position at the time of release were detected by scintigraphic evaluation.Results The different types pulsed release tablets all can achieve the lag time in vivo.Conclusion Scintigraphic study is the first considered method to evaluate the in vivo behaviour of the new formulation.
ABSTRACT
Objective: To compare the pharmacokinetics and bioavailability of verapamil hydrochloride pulsed release tablets with core tablets. Methods: Latin test was employed in the single oral administration of the Ⅲ,Ⅳ type of pulsed release tablets and core tablets in 8 volunteers. The pharmaceutics behavior of the tablet in vivo was evaluated by the lag time, c max ,AUC and so on. Results: The pharmacokinetics results demonstrated that the Ⅲ type of pulsed tablet in humans could be released after about 4 h lag time. In a proper range, pulsed release tablets only changed the beginning time while c max and AUC were not different from the core tablets. Conclusion: A new system to reduce the early morning symptoms of ischemic heart disease is prepared. [