Advancing therapeutics with targeted formulations of hydrogen sulphide donors

Hydrogen sulphide (H₂S), is a well described essential physiological molecule that is finely balanced to maintain cellular functions. Considering its important biological roles, H₂S has promising therapeutic potential resulting in the development of many H₂S donors. Such donors have proved to have therapeutic benefit in cognitive pathways, inflammation, reproduction, and the regulation of blood pressure. However, controlled delivery and targeted administration of this reactive and hazardous gas are necessary yet challenging due to its rapid diffusivity, and toxicity at high doses. Drug delivery systems are vital for the effective administration of many active pharmaceutical excipients, and H₂S donors stands to benefit significantly from the tuneable physical, chemical, and pharmacokinetic properties of various formulation systems. To date, few studies have focused on the formulation and delivery aspects of H₂S and its donors. Instead, H₂S usually is administered either by inhalation or via site-specific injections of donor solution. Whilst therapeutic benefit has been observed following such administration, these are not patient friendly solutions. This review focuses on highlighting the advances in H₂S donor formulations and their ability in sustaining the release of H₂S as well as improving drug targeting.