February 14, 2012
Saquinavir is a protease inhibitor. These drugs prevent the protease enzyme from working. HIV protease acts like a chemical scissor. It cuts the raw material for HIV into specific pieces needed to build a new virus. Protease inhibitors "gum up" these scissors.
The first version of saquinavir was Invirase. It worked well for some people, but it was not absorbed very well. Fortovase was developed. It was absorbed much better, so more of the drug got into the bloodstream. However, ritonavir (see Fact Sheet 442) is a very effective way to boost Invirase levels. Manufacture of Fortovase was discontinued in 2006. See "How Is It Taken?" below for more information.
Fact Sheet 404 has more information about guidelines for the use of ART.
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.
In late 2004 the FDA approved a 500 mg dosage of saquinavir. This cuts the saquinavir pill count from 5 per dose (with the old 200 mg version) to 2 per dose. Different doses may be used in some combinations.
Saquinavir should be taken within two hours after a full meal or a large snack. It is absorbed better if you take it after eating foods that are high in calories, fat, and protein. This should be less important when saquinavir is boosted with ritonavir. However, the official food recommendations have not been changed.
When you take it home, you can keep it at room temperature in tightly closed bottles.
Fact Sheet 442).
In 2010 the FDA issued a warning that the use of saquinavir boosted with ritonavir carries a slight risk causing abnormal heart rhythm. Your health care provider should check your heart before starting saquinavir.
Fact Sheet 442). Do not combine Saquinavir with Tipranavir/ritonavir. These interactions can change the amount of each drug in your bloodstream and cause an under- or overdose. New interactions are being identified all the time.
Drugs to watch out for include other ARVs, drugs to treat tuberculosis (see Fact Sheet 518), for erectile dysfunction (such as Viagra), for migraine headaches, and for heart rhythm (antiarrhythmics). Taking ritonavir together with saquinavir can cause an irregular heartbeat. Interactions are also possible with several antihistamines (allergy medications), sedatives, drugs to lower cholesterol, and anti-fungal drugs. Digitalis levels can be dangerously increased by Saquinavir. Garlic capsules might lower Saquinavir levels. The antacid omeprazole, sold as Prilosec and under other names, can greatly increase Saquinavir levels. Make sure that your health care provider knows about ALL drugs and supplements you are taking.
Saquinavir does not appear to have any significant interaction with methadone, except that Saquinavir taken with ritonavir can lower methadone levels. Watch for signs of excessive sedation if you take saquinavir with buprenorphine.
Some birth control pills may not work if you are taking saquinavir. Talk to your health care provider about how to prevent an unwanted pregnancy.
Grapefruit juice increases saquinavir levels. Avoid drinking it when taking saquinavir, especially if saquinavir is being boosted with ritonavir.
The herb St. John's Wort (see Fact Sheet 729) lowers the blood levels of some protease inhibitors. Do not take it with saquinavir.