Abstract: Carvedilol is a poorly water-soluble oral antihypertensive agent, with problems of variable bioavailability and bio-inequivalence related to its poor water-solubility. This work investigated the possibility of developing Carvedilol tablets, allowing fast, reproducible, and complete drug dissolution, by using drug solid dispersion in polyethylene glycol. Solubility studies were performed to investigate the drug-carrier interactions in solution, X-ray powder diffraction, were used to characterize the solid state of solid dispersions. The tablets were prepared by direct compression technique. The prepared tablets were evaluated for thickness, uniformity of weight, content uniformity, hardness, friability, wetting time, in vitro disintegration time and in vitro drug release. The tablets apart from fulfilling all official and other specifications, the Carvedilol dissolution profile from the newly developed tablets was clearly better than those from various conventional tablets at the same drug dosage. The stability studies conducted as per ICH guidelines at 40° and 75% RH showed insignificant loss in drug content and on physical evaluations at the end of six months.
The concept of Fast dissolving Drug Delivery System emerged from the desire to provide patient with more conventional means of taking their medication. It is difficult for many patients to swallow tablets and hard gelatin capsules. Hence they do not comply with prescription, which results in high incidence of non-compliance and ineffective therapy.1 In some cases such as motion sickness, sudden episodes of allergic attacks or coughing and unavailability of water, swallowing conventional tablets may be difficult.2 Particularly the difficulty is experienced by pediatric and geriatric patients. Such problems can be resolved by means of Fast Dissolving Tablet. When put on tongue, this tablet disintegrates instantaneously, releasing the drug, which dissolves or disperses in the saliva. Some drugs are absorbed from the mouth, pharynx and esophagus as the saliva passes down into the stomach. In such cases, bioavailability of drug is significantly greater than those observed from conventional tablet dosage form.1,3 Carvedilol is both an alpha and a beta adrenoreceptor-blocking agent used in the treatment of various cardiovascular disorders such as angina pectoris, cardiac arrhythmia and hypertension. Its biological half-life (2.2 hours) is very short and it is 90% absorbed from GIT, but its bioavailability is only 10-20% indicating extensive first pass metabolism in liver. In view of substantial first pass effect and its shorter plasma half-life, therefore is an ideal drug candidate for rapid release drug delivery system.