Which medication is effective in reducing the risk for HIV infection in high-risk individuals?

Truvada, which is a combination of two antiretroviral medications (tenofovir disoproxil fumarate and emtricitabine), is utilized in a preventative approach known as pre-exposure prophylaxis (PrEP). This regimen is specifically designed for individuals at high risk of contracting HIV, significantly reducing the likelihood of infection when taken consistently. Studies have shown that when used effectively, Truvada decreases the risk of HIV transmission by more than 90%.

In contrast, the other options listed do not serve the same purpose in HIV prevention. Abacavir is an antiretroviral medication used to treat HIV infections, rather than to prevent them. Cromolyn is primarily an anti-inflammatory medication used for asthma and allergic conditions, with no role in HIV prevention. Methdilazine is an antihistamine and does not have any implications for HIV treatment or prevention. Thus, Truvada stands out as the only effective choice in the context of reducing the risk for HIV infection in high-risk populations.