Adsorption and release of terbinafine hydrochloride: Effects of adsorbents, additives, pH, and temperature

The paper describes results obtained within the study of factors affecting the process of an antifungal drug — terbinafine hydrochloride adsorption on two different adsorbents — charcoal and silicagel. The effects of the adsorbent area, pH value, temperature and additives (polymers — methyl cellulose and hydroxypropyl cellulose) were analyzed and their impact on the adsorption of terbinafine was derived. The increase of pH and temperature, and the presence of additives decreased the amount of terbinafine adsorbed on the adsorbents. Terbinafine is currently applied both perorally and topically. Hydrogels, i.e. compositions of a drug, additives and water, are, due to their advantageous properties, preferred topical dosage forms. Mass fraction of additives of 1 % to 4 % were studied from the view point of drug release. This study shows that both the sort and the concentration of polymers influence the drug release from hydrogels significantly.