With each advancement in medicine, we are faced with the need for an effective method of drug delivery which is easy for the patient and maintains the bioavailability of the drug. Sustained release (SR) dosage is such a method, where discharge of drug is achieved for prolonged period. Such tuitions are used to provide a primary dose, obligatory for a usual therapeutic response, trailed by a steady release of the active constituent in quantities appropriate to maintain the required therapeutic reaction for the time required, usually 8-12 hrs. The sustained release drug delivery (SRDD) method has some potential advantage like; sustained release rate, reduction in dose frequency, dose maintenance in plasma, improved patient compliance, reduced toxicity due to overdose, reduction in fluctuation of peak valley concentration. (Isha et al. 2012)
Polymers are used in SRDD because of their quality of self-transforming and longer activity. For decades, polymers have been playing an important role as excipients in tablet and capsule formulation and offer functions such as drug targeting. They are employed successfully in SRDD because of their low molecular weight. (Rao et al. 2012) The use of naturally arising plant based polymers become very imperative in the expansion of SR dosage forms and employed in many preparations based on their molecular weight and properties. Natural polymers are among the most prevalent hydrophilic polymers because they are cheap to run, governing acceptance, non-toxic in nature, reasonable and obtainability. Okra gum, Xanthan gum, Karaya gum, Guar gum etc are the most popular naturally occurring polymers act as thickening agents and drug release retardants used in cosmetics, pharmaceuticals and food products.(Rajamma et al. 2012)
Xanthan gum is extensively used in the formulation of sustained release matrix tablets as it is biodegradable, non-toxic hydrate and swells. Pure culture fermentation procedure of a
carbohydrate with Xanthomonas compestris is used to produce Xanthan gum. It is a sodium, calcium or potassium salt of a high molecular weight polysaccharide having D-glucuronic acid, D-glucose and D-mannose. (Sekhar et al.2011) This gum is selected as it is widely available and cheaper as compared to other polymers currently available (Rajesh et al.2009).
Hypertension is well-defined as a systolic blood pressure of > 140 mm Hg and diastolic blood pressure of>90 mm Hg. Hypertension is threat for myocardial infarction, congestive heart failure, stroke, end stage renal disease and peripheral vascular disease. The World Health Organization stated that suboptimal blood pressure (systolic blood pressure>160) is accountable for 62% of cerebrovascular diseases and 49% of ischemic heart diseases. (Parvathi et al.2012)
Indapamide is a thiazide like diuretic that is lipid soluble and has a long duration of action. It has antihypertensive effect at low doses, while having minimal diuretic effect. It decreases the reabsorption of sodium by inhibiting Na+/Cl- transporter. (Hossain MA et al. 2013). It shows anti-hypertensive activity in SR at a dosage of 1.5mg/day. Pure Indapamide is almost insoluble in water (0.75 mg/l) and poorly absorbed from gastro intestinal tract. Indapamide has half-life of 14-18 hours and poor bioavailability of 30-40%. (Sanam et al. 2012)
Present study was conducted to formulate sustained release dosage form of Indapamide used for the treatment of hypertension using natural polymer xanthan gum as a release retardant material.