Pholcodine: treatment options for dry cough
Pholcodine (3-O-morpholinoethylmorphine) is a centrally acting antitussive derived from morphine, used for the symptomatic relief of colds and flu in children and adults. Pholcodine is a good choice of drug to treat persistent coughs because it has a long half-life, meaning less dosage requirements, and its safety in children has been established as it is registered for use in children from age two. Although pholcodine is derived from morphine, it causes little (or no) analgesia or euphoria. After oral absorption, it crosses the blood–brain barrier to act in the medulla oblongata by inhibiting the peripheric reflexogenic receptors, also known as the “cough centre”, thus increasing the threshold for coughing. Pholcodine interacts with central nervous system (CNS) depressants, monoamine oxidase inhibitors (MAOIs), neuromuscular blocking agents (NMBAs) and drugs that inhibit hepatic enzymes. Suppressants as a class are known to cause gastrointestinal and central effects; however, studies highlight that these rarely occur. Pholcodine is superior to other antitussives such as codeine because of its longer half-life, safer toxicity profile and minimal risk of addiction. The benefits of pholcodine continue to outweigh its risks, and patients can continue taking pholcodine containing medicines.