December 12, 2011
There are no absolute rules about when to start ART. You and your health care provider should consider your CD4 cell count, your viral load, any symptoms you are having, and your attitude about taking ART. Fact Sheet 404 has more information about guidelines for the use of ART.
If you take ritonavir with other ARVs, you can reduce your viral load to extremely low levels, and increase your CD4 cell counts. This should mean staying healthier longer.
Ritonavir makes the liver work more slowly. This can increase the blood levels of some drugs, including other protease inhibitors. This can cause some dangerous interactions with other drugs.
Ritonavir is rarely used as a protease inhibitor any more. It is difficult for patients to tolerate. However, ritonavir is frequently used to increase (boost) blood levels of other protease inhibitors. The dose used for boosting is much smaller than the full anti-HIV dose and causes fewer side effects.
Fact Sheet 126 for more information on resistance.
Sometimes, if your virus develops resistance to one drug, it will also have resistance to other ARVs. This is called "cross-resistance."
Resistance can develop quickly. It is very important to take ARVs according to instructions, on schedule, and not to skip or reduce doses.
Ritonavir is mostly used to increase the blood levels of other protease inhibitors. Usually 100 or 200 mg are taken with each dose. Be sure you know how much ritonavir your health care provider has prescribed for you, and when and how to take each dose.
A small amount of ritonavir is included in capsules of Kaletra as a booster. Kaletra is also manufactured by Abbott.
During 1998, a liquid form of ritonavir was developed. Many people think the liquid version tastes bad. However, some people find the liquid more convenient, especially for children. The liquid version should not be refrigerated. Shake the bottle before taking each dose.
Your pharmacist must keep the ritonavir soft-gel capsules refrigerated. You should keep ritonavir in your refrigerator, but it can also stay out at room temperature (below 77° F, or 25° C) for up to 30 days.
A new 100 mg tablet was approved in 2010. It does not need to be refrigerated. The tablet must be taken with a meal.
If full-dose ritonavir is used for adults or children, the dose is gradually increased over the first few days to reduce side effects.
Side effects made about one-third of people stop taking ritonavir in some clinical trials. However, there are far less side effects with the lower "booster" doses of ritonavir.
For many people, the side effects of ritonavir lasted only 2 to 4 weeks. If they lasted beyond 4 weeks, in most cases they were permanent.
There can be dangerous interactions with drugs for pulmonary arterial hypertension or erectile dysfunction such as sildenafil (Viagra) or other drugs with names ending in "-afil", drugs to treat asthma, and for heart rhythm (antiarrhythmics.) Taking ritonavir together with saquinavir can cause an irregular heartbeat. Other drugs to watch out for include other ARVs, drugs to treat tuberculosis (see Fact Sheet 518), and for migraine headaches. Interactions are also possible with several antihistamines (allergy medications), sedatives, drugs to lower cholesterol and anti-fungal drugs. Make sure that your health care provider knows about ALL drugs and supplements you are taking.
Ritonavir lowers blood levels of methadone. Watch for signs of excessive sedation if you take ritonavir with buprenorphine.
Some birth control pills may not work if you are taking ritonavir. Talk to your health care provider about how to prevent an unwanted pregnancy.
The herb St. John's Wort (see Fact Sheet 729) lowers the blood levels of some protease inhibitors. Do not take it with ritonavir.