The main objective of the study is to describe the pharmacology and safety of oral over-the-counter cough expectorants and suppressants. Also, it will present recommendations for the usage of these agents in solid-organ transplant recipients that would be based on the possibility for adverse drug events or drug-disease interactions.

Data from journal articles and even other sources that described the safety and pharmacology of over-the-counter cough suppressants and expectorants, drug-disease interactions and drug-drug interactions with immunosuppressive agents were reviewed.

Possible and reported drug-drug interactions between immunosuppressive agents and over-the-counter cough medications dextromethorphan, guaifenesin, diphenhydramine and codeine were assessed on the basis of pharmacodynamic and pharmacokinetic principles. Interactions between the cough medications and the body’s physiological changes after the transplantation were also assessed.

The study concluded that diphenhydramine needs additional monitoring while treating cough in transplant recipients due to its anticholinergic properties and also due to the probable interactions with cyclosporine. In most transplant recipients, dextromethorphan can be used, while more caution should be taken if the patient has undergone liver transplant or has some liver impairment. Also, guaifenesin could be used in transplant beneficiaries but with great caution in patients with kidney or lung transplants and in renal impairment patients. Another option for cough is codeine in combination with guaifenesin and can be used in most transplant patients. It should be monitored carefully for any adverse events in patients with reduced renal function.

Source: Gabardi S, Carter D, Martin S, Roberts K. Recommendations for the proper use of nonprescription cough suppressants and expectorants in solid-organ transplant recipients. Prog Transplant. 2011 Mar; 21(1):6-13; quiz 14.