Published: 2 March 2017
Prescriber Update 38(1): 10
Patients often fail to inform healthcare professionals about the dietary supplements, complementary medicines or illicit drugs they are taking. However, each of these categories includes substances that can interact with medicines, sometimes with serious, even fatal consequences.
The United Kingdom’s medicines regulator (Medicines and Healthcare products Regulatory Agency, [MHRA]) recently received a Coroner’s report regarding the death of a man from a subarachnoid haemorrhage after a suspected interaction between citalopram and cocaine1. The UK’s Pharmacovigilance Expert Advisory Group identified plausible mechanisms that could lead to a subarachnoid haemorrhage from this interaction, including hypertension related to cocaine and an increased bleeding risk with citalopram1.
Interactions between prescription medicines and illicit drugs may result in adverse outcomes, including toxicity or a reduction in therapeutic effect2. The potential interactions with any illicit drug should be considered when prescribing medicines, as well as in patients who present with suspected adverse reactions to medicines1.
To ensure appropriate prescribing, an adequate patient history should be taken, including the current and recent use of all medicines (including non-prescription, complementary and alternative medicines)3. Open and effective communication is essential and should be encouraged between patients and healthcare professionals4.
The New Zealand Formulary includes potential interactions with illicit drugs in its interaction checker, (http://nzf.org.nz/nzf_1). When using the interaction checker enter the name of the medicine rather than the illicit drug.