Selzentry™ – brand name

maraviroc – generic name

Selzentry belongs to a class of HIV drugs called entry inhibitors.

HIV must get inside normal cells to do its damage. In order to get inside the cells, HIV uses “keys” called receptors that are located on the surface of the cells. HIV attaches to the CD4 “key” and also to either the CCR5 “key” or the CXCR4 “key” to “unlock” the cell.

In the early stages of HIV disease, HIV uses the CCR5 “key” to get inside the cell 80–90% of the time. The form of the virus that attaches to the CCR5 “key” is called “CCR5-tropic” or R5 virus. Selzentry works by blocking HIV from using the CCR5 “key” to enter normal cells.

However, HIV can change over time, and it can take many forms. In later disease stages, approximately 50% of patients are infected with HIV that enters cells by using the CXCR4 “key”. The form of the virus that attaches to the CXCR4 “key” is called “CXCR4-tropic” or X4 virus. Selzentry does not block HIV from using the CXCR4 “key” to enter normal cells.

If you are being treated with Selzentry and your virus changes from R5 to X4, a rapid fall in CD4 cells normally occurs, and Selzentry will no longer work to block HIV from entering normal cells. In some cases, HIV may develop into strains that can use both R5 and X4 “keys” (called “dual-tropic” strains), or a person may be infected with a mixture of HIV strains, some that can use the R5 “key” and some that can use the X4 “key”. Selzentry will not block these mixed strains of HIV.

Since Selzentry only works by blocking HIV from using the R5 “key” to enter normal cells and does not work against HIV strains that use the X4 “key” or against strains that use both the R5 and X4 “keys”, patients must first have a blood test to determine whether their virus uses R5, X4, or both to enter normal cells.

The Food and Drug Administration (FDA) has approved Selzentry for use in combination with other anti-HIV drugs in HIV-infected adult and adolescent patients who are:

• at least 16 years of age
• have failed treatment with other anti-HIV drugs
• have been shown to be infected with HIV strains that use the CCR5 co-receptor (and not the CXCR4 co-receptor) to infect normal cells.

Your doctor can perform a blood test (called a tropism assay) to determine whether your strain of HIV uses the CCR5 receptor.

Selzentry is supplied in:

• 150 mg and 300 mg coated tablets

Selzentry should be taken in combination with other anti-HIV drugs. The recommended doses depend on what other drugs are combined with Selzentry™ and are as follows:

Selzentry can be taken with or without food.

Selzentry must be used in combination with other anti-HIV medications to treat HIV.

Tell your doctor if you have liver or kidney problems, diabetes, hemophilia, or a history of having your blood pressure drop when you stand up.

As with all HIV drugs, Selzentry should be taken only as prescribed by your doctor. Missing or skipping doses can cause blood levels of the drug to fall too low and the virus can become resistant to the drugs. This may cause the drugs to stop working.

If you miss a dose of Selzentry, you should take a dose as soon as possible and then take the next dose at the regularly scheduled time. However, if it is less than 6 hours before the next scheduled dose when you realize you have missed a dose, you should just skip the missed dose and take the next dose at the regularly scheduled time.

Selzentry, combined with other anti-HIV drugs, may be used for people whose HIV disease has gotten worse while taking anti-HIV drugs other than Selzentry. Selzentry is not yet recommended for people who are taking anti-HIV drugs for the first time.

Your doctor can do a special blood test (called a tropism assay) to help determine whether Selzentry is likely to work for you.

If your virus develops resistance to Selzentry, the drug may stop working or may not work as well for you. Fuzeon and Invirase have been shown to be effective against HIV that has become resistant to Selzentry.

Sometimes taking more than one medication can cause drug interactions. The dose of Selzentry may have to be adjusted depending on what other medications you are taking (see table above under “How should I take Selzentry”). You should not take Selzentry with products containing St. John’s Wort. Selzentry does not interact with birth control pills, zidovudine (Retrovir), lamivudine (Epivir), co-trimoxazole, or midazolam (Versed).

Be sure your doctor knows about all the medications you are taking (including over-the-counter, prescriptions, street drugs, and herbs), even if you only use them occasionally.

For more information and additional resources to check interactions between the particular drugs you are taking, see our info sheet on drug interactions or go to

http://www.hiv-druginteractions.org/

OR

http://hivinsite.ucsf.edu/insite?page=ar-00-02

It is not unusual to experience Selzentry side effects. However, they may be temporary and may go away as your body adjusts to the medication. If you experience any of the side effects listed below, call your doctor for advice. Do not just stop taking your medication.

• diarrhea
• swelling (fluid)
• sleep problems
• urinary problems
• cough
• fever
• cold-like symptoms
• rash
• muscle pain
• stomach pain
• dizziness
• A drop in blood pressure when standing up that can cause dizziness or fainting.

More serious side effects (may or may not be related to Selzentry™):

• Liver toxicity: this may be associated with an itching rash, higher levels of blood cells called eosinophils, and higher levels of chemicals called immunoglobulins, as well as higher levels of liver enzymes in the blood.
• Heart problems, including heart attack.
• Immune Reconstitution Syndrome - People who are starting HIV treatment for the first time may develop Immune Reconstitution Inflammatory Syndrome or IRIS. IRIS can happen as a result of the immune system getting stronger and responding to an HIV-related infection such as Mycobacterium avium infection (MAC), cytomegalovirus (CMV), Pneumocystis jirovecii pneumonia (PJP), or tuberculosis (TB). People may have been treated for these infections in the past or may not even know they have them. If you notice any unusual symptoms soon after starting HIV drugs for the first time, let your doctor know right away so you can be evaluated and treated, if necessary.

If you are experiencing persistent, unusual, or serious side effects, call your doctor right away.

In the clinical trials conducted for approval of Selzentry, only 10.7% (68 patients) were women. Therefore, very little is known about whether Selzentry might act differently in women than it does in men.

Selzentry should be used in pregnant women only if the potential benefit outweighs the potential risk to the baby. No studies have been done in pregnant women treated with Selzentry. However, studies of Selzentry in pregnant animals did not show any increased risk for birth defects in their offspring. The company that makes Selzentry has established an Antiretroviral Pregnancy Registry to collect information on pregnant women who take Selzentry. If you are pregnant and taking Selzentry, your doctor can register you by calling 1-800-258-4263.

Mothers who are taking Selzentry should not breast-feed their children.

Check with your doctor about the best treatment options for you and your baby if you are thinking of getting pregnant.