Pharmacotherapy Newsletter

Volume 1, Issue 38, 10/05/2009

Question

Which one of the antiretrovirals used for the treatment of HIV infection is known to cause a false positive for marijuana (tetrahydrocannabinol, THC) on drug screen and why?

Answer

The use of antiretrovirals for the management of human immunodeficiency virus (HIV) infection has clearly had a positive impact on the morbidity and mortality related to the disease.(1)  Unfortunately, their use frequently results in the development of many side effects.(1)  An example of one of the most common side effects is nausea.  Furthermore, many HIV patients may struggle with weight loss, lipodystrophy, changes in appetite, psychiatric disorders and pain syndromes that may cause some patients to resort to the use of marijuana (cannabis; tetrahydrocannabinol [THC]) to reduce or relieve these symptoms.(2-4)  In addition, the mechanism by which the patient contracted HIV (such as intravenous drug use) may prompt the clinician to monitor the patient for use of illegal drugs.(5-8)  As such, the management and monitoring of an HIV infected patient may include factors that fall outside of the normal monitoring parameters related to viral control.  One such parameter may be the administration and appropriate interpretation of random drug screens in certain patients.  

A number of medications can cross react with various lab assays and thus should be taken into consideration.  Of all of the antiretrovirals on the market, only the... 

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