Potential side effects and toxicity: Most common include: diarrhea (15-20% of patients in Study 542), stomach discomfort, nausea, gas, weakness and rash.
As seen with all other protease inhibitors are increased levels of cholesterol and triglycerides, except possibly unboosted Reyataz (atazanavir) and these increased levels may be associated with heart disease. Other possible side effects are lipodystrophy (body fat changes, including thinning of the face, arms and legs, with or without fat accumulation in the stomach, breasts and sometimes the upper back), onset of new cases or worsening of diabetes (see your doctor promptly) and increased bleeding in hemophiliacs.
Potential drug interactions: In general, less severe interactions compared to other drugs in this class.
Do not take with Tambocor (flecainide), Rythmol (propafenone), Versed, Cordarone (amiodarone), Halcion, Hismanol, Seldane, rifampin, ergot derivatives (such as Cafergot, Wigraine and Methergine, D.H.E. 45, in any form—serious interactions seen with dilation during gynecological exams), garlic supplements, or the herb St. John’s wort. Do not use Zocor (simvastatin) or Mevacor (lovastatin); lipid-lowering alternatives are Lipitor (atorvastatin), Lescol, and Pravachol (pravastatin), but they should be used with caution due to potential for liver toxicity. Rifampin and Viracept should not be used together.
Blood levels of Viracept are reduced by rifampin and may be reduced by phenobarbital, phenytoin, and carbamazepine (Tegretol and others). Fortovase levels increase three-to-five-fold, Crixivan increases 50% (see Crixivan for potential drug interactions). Mycobutin (rifabutin) dose must be decreased when used with Viracept. Prescriber may need to adjust doses of any of these drugs accordingly.
Protease inhibitors increase blood levels of Viagra (sidenafil citrate), Cialis (tadalafil) and Levitra (vardenafil). Use with caution. Initially the Viagra dose should be 12.5 mg (1/2 of 25 mg tablet) and increased as needed and tolerated. It’s recommended that people on PIs do not exceed 25 mg of Viagra in a 48-hour period because of potential for serious reaction. Use Cialis at reduced doses of 10 mg every 72 hours and Levitra at reduced doses of no more than 2.5 mg every 72 hours, with increased monitoring for adverse events.
The effectiveness of birth control pills may be decreased when taking Viracept; women and their male partners should consider the use of alternative contraception methods with barrier.
Tips: Do not leave pharmacy without anti-diarrhea meds such as Immodium, Tums or other calcium products. Taking a 500 mg calcium supplement with doses hugely decreases diarrhea. Also try Solgar oat bran tablets, psyllium husk fiber bars and pancreatic enzymes (all with meals). As an extra precaution, take a change of clothes with you everyday for the first several weeks—stick it out, most often symptoms improve after two or three weeks. The oral powder tastes horrible and requires a large amount for mixing into food. People using Viracept can crush adult tablets for use in children or dissolve tablets in a small amount of water. Acidic food or juice (e.g. orange/apple juice or apple sauce) not recommended in combination with Viracept, due to resulting bitter taste. To get the full benefit of Viracept by increasing its level in the body, it must be taken with a meal of at least 500 calories, with at least 20% to 50% of those calories coming from fat. Examples of meals that help to get to adequate food intakes include: Taco Bell Breakfast Burrito and 8 oz of non-acidic juice (650 calories, 35% from fat) or Subway Tuna Sandwich including potato chips and 8 oz of skim milk (703 calories, 41% from fat).
Doctor
Nelfinavir (NFV) quickly surpassed indinavir as the most widely prescribed PI in the late 1990s. This was primarily due to the reduced side effects (such as no kidney stones), twice-daily dosing (although initially it was dosed three times a day), and ability to be taken with food. Its main side effect is diarrhea, which in some patients is severe and intolerable. Like other PIs, it also can lead to elevated triglyceride levels. It is now recommended to take Viracept with food, as this greatly increases absorption. Many head-to-head studies now show nelfinavir to be somewhat less potent than other PIs and its use is in decline. It does have proven safety in pregnant women and hepatitis C patients.—Chad J. Zawitz, MD
Activist
The most popular PI right after Crixivan. It was pushed heavily as first line treatment in 1998–2000 with claims that you could use any other PIs after you failed this one. It can cause severe explosive diarrhea and insulin resistance. When Kaletra came in, Viracept use started to drop fast. The new formulation, a little too late, seems to cause less GI distress, but most doctors are not excited about the drug anymore. It is being marketed heavily now as the PI that does not need Norvir boosting, although I doubt that this is an asset, since most Norvir-booted PIs have shown better efficacy than this pony. In fact, most PIs were studied in comparison with this drug so that they could end up looking better. It is still a very important PI in pregnancy use.—Nelson Vergel
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