Preparation and evaluation of verapamil hydrochloride microcapsules.

Verapamil was encapsulated with ethylcellulose (EC) and cellulose acetate (CA) in various ratios of drug and polymer by the hot melt technique and the prepared microcapsules were evaluated for size range, drug content, drug release profiles, and kinetics of drug release. The microcapsules were compressed into tablets to study the variation of drug release between the 2 types of formulations (ie, microcapsules and tablets). The size analysis of prepared microcapsules was done by a standard sieving method and in vitro dissolution studies were carried out in USP XXI dissolution test apparatus in 0.1 N HCl as dissolution media to study the drug release profiles of the microcapsules. Scanning electron microscopy studies were carried out to investigate the surface characteristics of the microcapsules prepared from both type of polymers. Drug release profiles from the compressed non-disintegrating matrix tablets prepared from the microcapsules were also investigated. All the microcapsules were discrete, free flowing, and reproducible with respect to size distribution and drug content. Maximum percentage of the microcapsules belonged to the size range of 35/50. Drug release durations of VERCA1 (drug: CA 3:1), VERCA2 (drug: CA 2:1), and VERCA3 (drug: CA 1:1) microcapsules were extended up to 3, 5, and 6 hours, respectively, and those of VEREC1 (drug: EC 3:1), VEREC2 (drug: EC 2:1), and VEREC3 (drug: EC 1:1) microcapsules were extended up to 4, 5, and 7 hours, respectively. The microcapsules of both types having a drug:polymer ratio of 1:1 had the slowest release rate in their respective categories. The microcapsules were compressed into nondisintegrating matrix tablets. The hardness of the tablets was tested using the Monsanto Hardness Tester and was found to be 6-7 kg/cm. All the tablets contained the drug verapamil within 100% +/- 5%. The drug release data of both the microcapsules and tablets prepared were examined kinetically, and the ideal kinetic model was determined for the drug release. The tablets prepared by compressing the microcapsule formulations were more satisfactory in releasing the drug at a controlled and uniform rate following Higuchian kinetics and the formulations VCACRT3 and VECCRT3 were able to control release of drug up to 12 hours. Thus, it is possible to formulate a single-unit, controlled-release dosage form of verapamil for oral administration at least once every 12 hours using the polymers CA and EC.

A comparison between povidone-ethylcellulose and povidone-eudragit transdermal dexamethasone matrix patches based on in vitro skin permeation.

The present study was designed to develop a suitable matrix type transdermal drug delivery system (TDDS) of dexamethasone using blends of two different polymeric combinations, povidone (PVP) and ethylcellulose (EC) and Eudragit with PVP. Physical studies including moisture content, moisture uptake, flatness to study the stability of the formulations and in vitro dissolution of the experimental formulations were performed to determine the amount of dexamethasone present in the patches were performed and scanning electron microscopy (SEM) photographs of the prepared TDDS were taken to see the drug distribution pattern. Drug-excipient interaction studies were carried out using Fourier transform infrared (FTIR) spectroscopic technique. In vitro skin permeation study was conducted in a modified Franz's diffusion cell. All the formulations were found to be suitable for formulating in terms of physicochemical characteristics and there was no significant interaction noticed between the drug and polymers used. In vitro dissolution studies showed that the drug distribution in the matrix was homogeneous and the SEM photographs further demonstrated this. The formulations of PVP:EC provided slower and more sustained release of drug than the PVP:Eudragit formulations during skin permeation studies and the formulation PVP:EC (1:5) was found to provide the slowest release of drug. Based on the above observations, it can be reasonably concluded that PVP-EC polymers are better suited than PVP-Eudragit polymers for the development of TDDS of dexamethasone.

Vanadium--an element of atypical biological significance.

The biological image of the transition element vanadium ferments a great deal of contradiction-from toxicity to essentiality. Importance of this element as micro-nutrient is yet to be unequivocally accepted by biologists and biomedical scientists. In spite of toxicity, it seems interesting to analyze the different biological roles of the element. Vanadium compounds have been proven to be associated with various implications in the pathogenesis of some human diseases and also in maintaining normal body functions. Salts of vanadium interfere with an essential array of enzymatic systems such as different ATPases, protein kinases, ribonucleases and phosphatases. While vanadium deficiency accounts for several physiological malfunctionings including thyroid, glucose and lipid metabolism, etc., several genes are regulated by this element or by its compounds, which include genes for tumor necrosis factor-alpha (TNF-alpha), Interleukin-8 (IL-8), activator protein-1 (AP-1), ras, c-raf-1, mitogen activated protein kinase (MAPK), p53, nuclear factors-kappaB, etc. All these seem to be not far from its recognition as an element of pharmacological and nutritional significance, which is revealed through its increasing therapeutic uses in diabetes. Vanadium is also emerging as a potent anti-carcinogenic agent. This review summarizes the developments related to vanadium biology as a whole by analyzing the general biochemical functions of vanadium.