Biomedical subjects

S A El-Nahhas

Publications and source records attributed to S A El-Nahhas.

3 recordsLinked to original sources

PubMed2006

Design of a transdermal delivery system for aspirin as an antithrombotic drug.

Aspirin has become the gold standard to which newer antiplatelet drugs are compared for reducing risks of cardiovascular diseases, while keeping low cost. Oral aspirin has a repertoire of gastrointestinal side effects even at low doses and requires high frequent dosing because it undergoes extensive presystemic metabolism. Transdermal delivery offers an alternative route that bypasses the gut and may be more convenient and safer for aspirin delivery especially during long-term use. This study comprised formulation of aspirin in different topical bases. Release studies revealed that hydrocarbon gel allowed highest drug release. In vitro permeation studies revealed high drug permeation from hydrocarbon gel. Several chemical penetration enhancers were monitored for augmenting the permeation from this base. Combination of propylene glycol and alcohol showed maximum enhancing effect and, hence, was selected for biological investigation. The biological performance of the selected formulation was assessed by measuring the inhibition of platelet aggregation relevant to different dosage regimens aiming to minimize both drug dose and frequency of application. The results demonstrated the feasibility of successfully influencing platelet function and revealed that the drug therapeutic efficacy in transdermal delivery system is dose independent. Biological performance was re-assessed after storage and the results revealed stability and persistent therapeutic efficacy.

Administration, Cutaneous↗

PubMed2006

A transdermal delivery system for glipizide.

Glipizide is one of the most commonly prescribed drugs for treatment of type 2 diabetes. Oral therapy with glipizide comprises problems of bioavailability fluctuations and may be associated with severe hypoglycaemia and gastric disturbances. As a potential for convenient, safe and effective antidiabetic therapy, the rationale of this study was to develop a transdermal delivery system for glipizide. For this purpose, inclusion complexes of the drug in beta-cyclodextrin (beta-CyD), dimethyl-beta-cyclodextrin (DM-beta-CyD), hydroxypropyl-beta-cyclodextrin (HP-beta-CyD), and hydroxypropyl-gamma-cyclodextrin (HP-gamma-CyD) were prepared. Several percutaneous formulations of the drug and the prepared complexes in different bases (o/w emulsion, polyethylene glycol, carboxymethyl cellulose and Carbopol) were developed. Release studies revealed an improved release of the drug from formulations containing glipizide-CyD complexes. Ex vivo permeation studies through full thickness rat abdominal skin were conducted, whereby the effect of several conventional penetration enhancers (propylene glycol [PG], oleic acid, urea, dimethyl sulfoxide, menthol, limonene and cineole) was monitored. Highest flux was obtained from ointments prepared with Carbopol gel base containing a combination of PG and oleic acid as well as ointments prepared in the same base utilizing glipizide-DM-beta-CyD complex and urea. In vivo studies on diabetic male Wistar rats revealed a marked therapeutic efficacy sustained for about 48 hours. In this respect, two formulations showed best biological performance. In the first formulation, the drug was incorporated in Carbopol gel base in the presence of 20% PG together with 15% oleic acid. The second was prepared by incorporating glipizide-DM-beta-CyD complex in Carbopol gel base in presence of 15% urea. The glucose tolerance test showed suppression of hyperglycaemia induced in glucose-loaded rats. The above-mentioned results might shed a strong beam of light on the feasibility of using glipizide in a transdermal delivery system for treatment of type 2 diabetes with the aim of improving both patient compliance and pathophysiology of the disease.

Acrylic Resins↗

PubMed1998

Cyclodextrins in acetazolamide eye drop formulations.

The interaction of acetazolamide with beta-cyclodextrin, (beta-CD), dimethyl-beta-cyclodextrin (DM-beta-CD) and trimethyl-beta-cyclodextrin (TM-beta-CD) was monitored spectrophotometrically. The results revealed formation of equimolar complexes. The apparent solubility of acetazolamide in water was found to increase linearly with increasing CD concentration. The effect of CDs on the permeation of acetazolamide through semi-permeable membranes and the topical delivery of acetazolamide was investigated. Maximum acetazolamide penetration was obtained when just enough CD was used to keep all acetazolamide in solution. For an acetazolamide concentration of 10 mg/ml, the optimum CD concentration appeared to be 3.5 mmol/l for beta-CD, 2.8 mmol/l for TM-beta-CD and 6.0 mmol/l for DM-beta-CD. The effect of CDs on the bioavailability of acetazolamide was assessed by measuring the intraocular pressure in rabbits. The results indicated that CDs have a significant influence on the biological performance of the drug leading to augmentation in its intensity of action and bioavailability as well as prolongation in its duration of action.

Acetazolamide↗