Address Concern for Antiepileptic-Antiretroviral Drug Interactions
A joint effort of the American Academy of Neurology (AAN) and
International League Against Epilepsy (ILAE) has led to the creation of
guidelines to aid physicians in selecting antiepileptic drugs (AEDs) for
patients with HIV/AIDS. Findings are published in the official ILAE
journal Epilepsia,
and Neurology®,
the medical journal of the AAN, and include suggested dosing regimens to
moderate potential interactions between AEDs and antiretroviral (ARV)
drugs.
According to a 2009 report from the World Health Organization (WHO),
more than 33 million individuals worldwide were living with HIV, another
2.6 million were infected with HIV and 1.8 million died from AIDS in
that year. Medical evidence shows that seizure disorders are common
among those with HIV. Additionally, those with HIV may also require AED
therapy for peripheral neuropathy symptoms and other HIV-related
disorders. Until now, formal antiepileptic drug (AED) treatment
guidelines did not exist for those with HIV/AIDS.
To establish the guidelines, Dr. Gretchen Birbeck from Michigan State
University in East Lansing and colleagues systematically reviewed
studies published in the medical literature between 1950 and 2010 to
determine the prevalence of co-usage of AEDs and ARVs and AED-ARV drug
interactions. Close to 4,500 articles related to AED and ARV usage or
drug interactions were identified; 68 full studies were reviewed and
data from 42 used in the analysis.
“Drug interactions between AEDs and ARVs could increase toxicity risk or
decrease efficacy in patients. These interactions could result in
progression to AIDS and/or reduced seizure control,” said Dr. Birbeck.
“Understanding potential risks associated with AED and ARV combinations,
and providing guidelines that help physicians select appropriate
therapies for their patients with epilepsy and HIV/AIDS, will ultimately
improve patient outcomes and possibly decrease the public health threat
of the development of drug resistant HIV.”
Findings show that up to 55% of HIV/AIDS patients may require AED
treatment. Patients with epilepsy and HIV/AIDS may need to adjust the
dosages of ARV medications to maintain proper therapeutic levels. The
authors suggest that patients taking phenytoin may require a 50%
increase in the dosage of lopinavir/ritonavir. For those receiving
valproic acid a reduction in the dosage of zidovudine may be necessary.
Various AED-ARV combinations may also require dosage adjustments
according to the study findings, and clinicians are encouraged to use
the Department of Health and Human Services treatment guidelines for
HIV/AIDS.
The authors recommend that patients on ARV regimens that include
protease inhibitors (PIs) or non-nucleoside reverse transcriptase
inhibitors (NNRTIs) avoid taking enzyme-inducing AEDS due to possible
virologic failure, which could lead to HIV progression or ARV
resistance. “Further study of AED-ARV interactions—specifically
first-line combinations often used in poorer countries where second-line
drugs may not be available—are needed,” concludes Dr. Birbeck.
