Human immunodeficiency virus is a virus that attacks cells in the immune system. These cells, called CD4 cells, help your body fight infection. HIV infection can lead to acquired immune deficiency syndrome, which is a later stage of the disease when the immune system has been severely damaged.
With a damaged immune system, the body has a harder time defending itself against bacteria, viruses and even some types of cancer. As a result, patients with HIV more often die from these complications than from the virus itself. Unlike in the past, HIV infections can now be well controlled with medications, and many patients live a stable life.
Anti-HIV medications are the keys to controlling an HIV infection. These medications are commonly known as "antiretrovirals" and can inhibit the HIV virus in different ways. Some prevent the virus from multiplying; others prevent the virus from entering healthy cells. The many classes of antiretrovirals include nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, CCR5 antagonists, protease inhibitors, integrase inhibitors and fusion inhibitors.
Doctors and researchers have developed ways to combine two or more of these types of medications to control HIV in the most effective way. These "highly-active" antiretroviral therapy treatment regimens may involve taking two or more pills a couple times a day. Some companies combine the medications into one pill, which could make it easier to take anti-HIV medications regularly.
Taking anti-HIV medications regularly and as directed by your doctor and pharmacist can help stop the virus from multiplying and attacking your immune system. It also prevents the virus from developing resistance, which is when the virus changes form and medications do not work as well.
Because you will be taking these medications for a long time, it's important to know that there are some common drugs that can interact with anti-HIV medications. You should especially keep this in mind when starting a new medication because such interactions can make your anti-HIV medications not work properly, even if you take them regularly. Some substances can also cause the anti-HIV medications to reach harmfully high levels in the blood, leading to more side effects.
What medications should I watch out for?
Several types of medications that your doctor prescribes can interact with anti-HIV medications. Examples include:
• Cholesterol-lowering medications
• Anti-arrhythmia medications
• Seizure medications
Products you can buy without a prescription can also cause anti-HIV medications to not work properly. Some of the most common over-the-counter medications that can do this include ones that help manage heartburn. Heartburn remedies that you can buy over the counter are similar to prescription medications for gastroesophageal reflux disease, and they interact with anti-HIV medications in the same way. The three types of these acid suppressant medications are:
• Antacids such as Alka-Seltzer, Brioschi, Gaviscon, Maalox, Mylanta, Rolaids, Tums
• H2 blockers such as Axid (nizatidine), Pepcid AC (famotidine), Pepcid Complete, Tagamet (cimetidine), Zantac (rantidine)
• Proton pump inhibitors such as Prevacid 24HR (lansoprazole), Prilosec OTC (omeprazole), Zegerid OTC (omeprazole and sodium bicarbonate)
Acid suppressants reduce the acid in the stomach to stop the irritation and heartburn symptoms that happen when acid leaks back into the esophagus. Some anti-HIV medications actually need acid in the stomach to be properly absorbed in your body. If there is not enough acid, there is a decreased amount of anti-HIV medication in your blood to fight the virus, even if you are taking the anti-HIV medications correctly. Having lower levels of anti-HIV medication puts you at risk for uncontrolled HIV and resistance.
Herbal drug products also lead to interactions. St. John's wort can make anti-HIV medication ineffective by lowering the levels of the anti-HIV medication in your blood. Garlic and vitamin C have also been shown to lower these levels. Milk thistle and echinacea can increase levels, leading to more side effects. It's best to avoid herbal products when taking anti-HIV medication, or to talk to your pharmacist before taking them.
|Instructions for Taking Acid-Suppresssing Medications with Anti-HIV Treatments|
|Anti-HIV Medication||Antacids||H2 Blockers||Proton Pump Inhibitors|
|Aptivirus (tipranavir)||Take Aptivirus at least two hours before or one hour after antacid||No information available||No information available|
|Lexiva (fosamprenavir)||Take Lexiva at least two hours before or one hour after antacid||Take Lexiva at least two hours before H2 blocker||No interaction|
|Edurant (rilpivirine); Complera (emtricitabine, rilpivirine, tenofovir, disoproxill fumarate)||Take these anti-HIV medications at least two hours before or four hours after antacid||Take these anti-HIV medications at least 12 hours before or four hours after H2 blocker||DO NOT USE|
|Reyataz (atazanavir) WITHOUT Norvir (ritonavir)||Take Reyataz without Norvir at least two hours before or one hour after antacid||Take Reyataz without Norvir at least two hours before or 10 hours after H2 blocker; No more than Pepcid (famotidine) 20 mg per dose twice a day||DO NOT USE*|
|Reyataz (atazanavir) WITH Norvir (ritonavir)||Take Reyataz with Norvir at least two hours before or one hour after antacid||Take Reyataz with Norvir at same time or 10 hours after H2 blocker; No more than Pepcid (famotidine) 20 mg per dose twice a day**||DO NOT USE|
|*can be used in some cases; ask your pharmacist
**Pepcid (famotidine) dose can be higher in some cases; ask your pharmacist
How can I prevent drug interactions?
There are several important things you can do to prevent drug interactions.
First, filling all your prescriptions at the same pharmacy allows your pharmacist to monitor any possible drug interactions. Whenever your doctor prescribes a new medication, your pharmacist can review all your medications to make sure there are no interactions.
Second, before buying an over-the-counter product, ask your pharmacist whether it will interact with your anti-HIV medication. Your pharmacist may give you special instructions on how to prevent any type of interaction. For example, taking acid suppressants a couple of hours before or after your anti-HIV medication might help prevent interactions. Table 2 gives instructions on how to schedule your acid suppressant medications with certain anti-HIV medications.
Third, it's usually best to avoid herbal products when taking anti-HIV medications, or to speak to your pharmacist for more information.
How can my pharmacist help?
Your pharmacist is the best resource to prevent drug interactions. Ask your pharmacist to look up any possible drug interactions if you start a new medication or want to buy an over-the-counter medication. Developing a good relationship with your pharmacist will assure that your HIV infection is treated properly and effectively.
Note: This article was originally published on Feb. 15, 2012 on PharmacyTimes.com. It has been edited and republished by U.S. News.