Abstract

Sustained release (SR) dosage forms enable prolonged and continuous deposition of the drug in the gastrointestinal (GI) tract and improve the bioavailability of medications characterized by a narrow absorption window. In this study, a new strategy is proposed for the development of SR dosage forms for theophylline (TPH). Design of the delivery system was based on a sustained release formulation, with a modified coating technique and swelling features aimed to extend the release time of the drug. Different polymers, such as Carbopol 71G (CP), sodium carboxymethylcellulose (SCMC), ethylcellulose (EC) and their combinations were tried. Prepared matrix tablets were coated with a 5 % (m/m) dispersion of Eudragit (EUD) in order to get the desired sustained release profile over a period of 24 h. Various formulations were evaluated for micromeritic properties, drug concentration and in vitro drug release. It was found that the in vitro drug release rate decreased with increasing the amount of polymer. Coating with EUD resulted in a significant lag phase in the first two hours of dissolution in the acidic pH of simulated gastric fluid (SGF) due to decreased water uptake, and hence decreased driving force for drug release. Release became faster in the alkaline pH of simulated intestinal fluid (SIF) owing to increased solubility of both the coating and matrixing agents. The optimized formulation was subjected to in vivo studies in rabbits and the pharmacokinetic parameters of developed formulations were compared with the commercial (Asmanyl(®)) formulation. Asmanyl(®) tablets showed faster absorption (t(max) 4.0 h) compared to the TPH formulation showing a t(max) value of 8.0 h. The C(max) and AUC values of TPH formulation were significantly (p < 0.05) higher than those for Asmanyl(®), revealing relative bioavailability of about 136.93 %. Our study demonstrated the potential usefulness of eudraginated polymers for the oral delivery of the sparingly soluble drug theophylline.

Links

Publisher Full Text

Authors

Emeje M, John-Africa L, Isimi Y, Kunle O, Ofoefule S

Institution

Department of Pharmaceutical Technology and Raw Materials Development, National Institute for Pharmaceutical Research and Development, Abuja, Nigeria. martinsemeje@yahoo.com

Source

Acta pharmaceutica (Zagreb, Croatia) 62:1 2012 Mar 1 pg 71-82

MeSH

Acrylates
Administration, Oral
Animals
Area Under Curve
Biological Availability
Carboxymethylcellulose Sodium
Cellulose
Chemistry, Pharmaceutical
Delayed-Action Preparations
Drug Carriers
Drug Compounding
Hydrogen-Ion Concentration
Intestinal Absorption
Male
Polymethacrylic Acids
Rabbits
Solubility
Tablets
Technology, Pharmaceutical
Theophylline

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

22472450