Soluble Drug Theophylline Sodium Glycinate from Different Suppository Bases

Theophylline Sodium Glycinate (TSG) loaded lipid-based suppositories were prepared and the effects of suppository bases and release modifiers (PEG 1500 and HPMC 15 cps) on in vitro release of TSG were investigated. Suppositories containing 300 mg TSG were prepared by fusion method. Bees wax, Carnauba wax, Stearic acid and PEG 4000 were used as hydrophobic bases. In vitro dissolution was carried out in aqueous and buffered media of pH 6.8 for 2 hours. The results showed that, the release rate of TSG is considerably slow from beeswax, carnauba wax and stearic acid based devices. However, substantial TSG release was observed from PEG 4000 based systems. Incorporation of PEG 1500 in beeswax, carnauba wax and stearic acid based suppositories increased the rate and extent of TSG release in buffer media. Inclusion of HPMC 15 cps in PEG 4000 loaded suppositories released TSG at a faster rate. Drug release was linear for all the formulation except PEG 4000 systems, which released drug in a biphasic pattern both in aqueous and buffered environment. Rate and extent of drug release was found to be a function of pH of the dissolution media. Key words: Theophylline sodium glycinate, Suppositories, In vitro release Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Does adenosine modulate the natriuretic response to ANP in normal dogs?

To determine if the usual natriuretic response to ANP could be altered by raising intrarenal levels of adenosine, ANP was administered to normal anesthetized dogs at 100 ng∙kg−1∙min−1 i.v. before and after the administration of adenosine (3 μg∙kg−1∙min−1) into the left renal artery (n = 8). For each kidney, the group mean ΔUNaV in response to ANP was unchanged by the presence of adenosine. However, following intrarenal infusion of adenosine, this unaltered average response for the infused kidney was achieved by either attenuation or exaggeration of the natriuresis to ANP in half the dogs, respectively. When intrarenal levels of extracellular adenosine were elevated by the i.v. infusion of dipyridamole in seven dogs, there was uniform exaggeration of an ANP-induced natriuresis by an average of 145 μequiv./min. The provision of theophylline by itself (an adenosine antagonist) had no effect on UNaV but prevented the dipyridamole-induced exaggerated natriuresis to ANP. The infusion of adenosine deaminase into one renal artery reduced the natriuretic response to ANP. We conclude that elevated intrarenal levels of adenosine will exaggerate an ANP-induced natriuresis possibly by altering intracytosolic Ca2+.Key words: theophylline, dipyridamole, purine receptors.

Design and In Vitro Evaluation of Chrono Modulated Theophylline Tablets

The objective of this research work was to prepare a chrono modulated delivery system to meet chronopharmacological needs of asthma. In this study theophylline was selected as a model drug. To meet this objective we considered an initial lag phase of release for 3-5 hrs and later a rapid (surge) release phase. To achieve surge release a rapidly releasing core tablet of theophylline was developed by admixing theophylline with effervescent granules and super disintegrants. The lag phase in release was achieved by coating the EV core tablets with release retarding polymer EUDRAGIT RS-100 containing HPMC, further over coated with enteric polymer CAP. The results indicate that a rapidly releasing EV tablet of theophylline cab be developed which when coated with the polymers a lag phase of 2 hrs was achievable followed by a surge release. Key Words: Theophylline, Chrono Modulated Drug Delivery, Asthma. doi:10.3329/sjps.v1i1.1782 S. J. Pharm. Sci. 1(1&2): 25-28

Impact of Granulation and Effect of Polymers on Theophylline Release from Matrix Tablets

The effects of plastic, hydrophilic and hydrophobic types of polymers and impact of granulation process were investigated on the release profile of theophylline from matrix systems. A comparative release characteristics were evaluated by the use of polymers from different theophylline matrices. Matrix tablets of theophylline using Methocel K4M, Ethocel 20 cps, Kollidon SR were prepared separately by direct compression and moist granulation process. In this investigation the feasibility of moist granulation technique in the development of sustained release matrix tablet of theophylline was studied. The kinetics of the dissolution process was determined by analyzing the dissolution data using various kinetic equations, e.g. zero-order, Higuchi and Korsmeyer equations. The mean dissolution time (MDT) was calculated for all the formulations. The analysis of the dissolution data showed that the release process involves erosion and diffusion. Drug release was different from different classes of polymeric matrices and from tablets prepared by different manufacturing processes. The results showed that the profile and kinetics of drug release were the functions of polymer type, polymer content and granulation process. Key words: Theophylline, Moist granulation, Direct compression, Methocel K4M, Ethocel 20 cps, Kollidon SR doi: 10.3329/dujps.v7i2.2168 Dhaka Univ. J. Pharm. Sci. 7(2): 133-139, 2008 (December)