In Vitro-Controlled Release Delivery System for Hydrogen Sulfide Donor

Hydrogen sulfide (H₂S) is having many potential pharmacological and physiological actions which reported that therapeutically useful concentration is low (100–160 μM) and a higher concentration could be toxic. Most of its donors produce it on coming into contact with water. All of these problems could be solved by a controlled-release delivery system which does not utilize water in any of its development steps. Therefore, 12 sustained release formulations were prepared by dissolving sodium hydrogen sulfide (NaHS)—a model H₂S donor—in polymer solutions, prepared by dissolving polymers (consisted of either polylactide (PLA) or polylactide co-glycolide (PLGA), containing free carboxylic acid or capped allyl ester end group) in a mixture of benzyl benzoate (BB) and benzyl alcohol (BA). The formulation was injected in simulated tear fluid (STF) from which samples were withdrawn at specified times and assayed for NaHS content. We found decrease in burst and overall release with increase in polymer concentration from 10 to 20% w/v. The formulations containing free end group showed significant (p?vs 21%). However, the overall release or the average amount released per hour was found to be significantly (p?2S was found to be maintained for 72 h which should be further increased to a month to make it a viable H₂S donor delivery system in addition to investigating toxicity profile specifically for the purpose of subconjunctival ocular delivery.KEY WORDS: controlled release, hydrogen sulfide, hydrogen sulfide donor, in situ gel forming, phase sensitive, smart polymer