Original Article FORMULATION AND EVALUATION OF LEVODOPA EFFERVESCENT FLOATING TABLETS K. CHAITANYA a SELLAPPAN VELMURUGAN a, b * , a Department of Pharmaceutics, KLR Pharmacy College, Paloncha, Telangana, India, b Department of Pharmaceutics, Sunrise University, Alwar, Rajasthan ,India. Email: willard_cbe@rediffmail.com Received: 08 Jan 2015 Revised and Accepted: 05 Feb 2015 ABSTRACT Objective: Levodopa is an immediate precursor of dopamine used in treatment of Parkinsonism disorders. The Levodopa effervescent floating tablets were prepared by direct compression technique, using different low density polymers (POLYOX different grades) in various drug polymer ratios. Methods: The Levodopa effervescent floating tablets were prepared by direct compression method. The floating tablets were evaluated for friability, thickness, hardness, weight variation test, drug content, in vitro release and floating properties. The drug excipients compatibility was evaluated by DSC and FT-IR study. Results: All the batches showed compliance with pharmacopoeia standards. Among all the formulation F4 containing PEO WSR 303 in 1:1 drug polymer ratio showed controlled drug release for 12h (99.15%) emerging as the best formulation and follow first order kinetics via, swelling, diffusion. An in vitro buoyancy study reveals that all batches showed good in vitro buoyancy. The DSC study revealed that there was no strong interaction between Levodopa and excipients. Stability studies were carried out for best formulation F4 (PEO WSR 303 in 1:1 drug polymer ratio) according to ICH guidelines. Stability studies (40±2oC/75±5% RH) for 3 month indicated that Levodopa was stable in floating tablets. Conclusion: Hence different grades of low density polymer (PEO) in various drug polymer ratios can be used to prepare Levodopa floating tablets for prolongation of gastric residence time with enhanced patient compliance. Keywords: Levodopa, Polyethylene oxide (PEO), Sodium bicarbonate, Floating drug delivery system, Effervescent floating tablets. INTRODUCTION Oral drug delivery is the most widely explored routes of administration among different routes that have been utilized for systemic delivery of drugs via the different dosage form. Oral route is considered most natural, suitable and most widely accepted one by the patients due to its ease of administration, patient acceptance, and cost effective manufacturing process [1]. An oral drug delivery system providing a uniform drug delivery can only partly satisfy therapeutic and biopharmaceutical needs, as it doesn’t take into account the site specific absorption rates within the gastrointestinal tract (GIT) [2]. Therefore, there is a need of developing a drug delivery system that releases the drug at the right time, at the specific site and with the desired rate. Invariably, conventional dosage forms do not maintain the drug blood levels within the therapeutic range for an extended period of time. The concept of gastro retentive drug delivery system came from the need to localize the drug at a certain site in the body [3]. It was suggested that compounding narrow absorption window drugs in a unique pharmaceutical dosage form with gastro retentive properties would enable an extended absorption phase of these drugs. Especially the site of drug absorption is mainly stomach or upper part of the small intestine, then it is necessary to retain the dosage form at the site of absorption, but the gastrointestinal transit is the limitation for such type of dosage forms [4]. Controlling the residence time of drug delivery system in a particular region of the gastrointestinal (GI) tract can be made via several approaches: Intragastric floating system, high density system, muco adhesive system, unfolding, extendable and expandable system and porous Hydrogels [5, 6]. On contact with the gastric fluid form a water impermeable colloidal gel barrier and bulk density<1 and thus remain buoyant in the stomach, for a prolonged period of time, without affecting the gastric emptying rate [7, 8]. Levodopa is clinically used for the treatment of Parkinsonism disorders and is the naturally occurring form of di hydroxy phenylalanine and the immediate precursor of dopamine. Levodopa is a metabolic precursor of dopamine [9]. It restores dopamine levels in extrapyramidal centers (substantianiagra) that atrophy in Parkinsonism. Levodopa is readily transported into the CNS and converted to dopamine in the brain. Large doses of Levodopa are required, because much of the drug is decarboxylated by dopamine decarboxylase to dopamine in the periphery [10]. The main limitation to the therapeutic effectiveness of Levodopa is having a short plasma half-life of 1 to 3 hours, low bioavailability and has a high solubility in the acidic pH [11, 12]. Levodopa uptake mainly takes place in an upper part of small intestine. It appears more plausible that slower delivery to the absorption area in the upper small intestine promotes the uptake of Levodopa. The gastroretentive drug delivery is able to prolong the retention time of a dosage form in the stomach, thereby improving the oral bioavailability of the levodopa by releasing before absorption area. The aim of the present investigation is to develop floating drug delivery system for Levodopa, which increases the gastric residence time, minimizes the problems associated with conventional dosage forms. MATERIALS AND METHODS Materials Levodopa was a gift sample from Hetero Pharma Ltd, Hyderabad. PEO WSR coagulant, PEO WSR 303 and PEO N 750 other polymers were received as the gift sample from Aurobindo Pharma, Hyderabad. Sodium bicarbonate, Talc and magnesium Stearate from SD fine chemicals Pvt. Ltd, Mumbai. Hydrochloric acid is from Merck specialties Pvt Ltd, Mumbai. Methods Levodopa floating tablet preparation Levodopa floating tablets were prepared by direct compression method. The different formulation composition is shown in table 1. All the powders passed through 40 mesh sieve. The required quantity of Levodopa, various PEO grades and sodium bicarbonate was mixed thoroughly. Talc and magnesium stearate were finally added as a glidant and lubricant respectively. The blend was directly compressed (6 mm and 7.5 mm diameter, circular flat faced punches) on a sixteen station rotary tablet punching machine (Cadmach Machinery Ltd., Ahmedabad, India). Each tablet contained 50 mg of Levodopa. All the tablets were stored in airtight containers for further study. International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 7, Issue 5, 2015 Innovare Academic Sciences