July 25, 2016
font size

Human Immunodeficiency Virus (HIV) (cont.)

Medical Author:
Medical Editor:

In this Article

What are protease inhibitors?

PIs block the action of an HIV enzyme called protease that allows HIV to produce infectious copies of itself within HIV-infected human cells. Thus, blocking protease prevents HIV in already-infected cells from producing HIV that can infect other, not yet infected cells.

PIs include

  • saquinavir (Invirase and Fortavase, SQV), which comes as the hard gel capsule Invirase (INV),
  • ritonavir (Norvir, RTV),
  • indinavir (Crixivan, IDV),
  • nelfinavir (Viracept, NFV),
  • fosamprenavir (Lexiva, FPV),
  • lopinavir/ritonavir (Kaletra, LPV/r),
  • atazanavir (Reyataz, ATV),
  • tipranavir (Aptivus, TPV),
  • darunavir (Prezista, DRV).

Each of these drugs has been shown to effectively reduce the viral load when used in combination with other active drugs.

LPV/r comes coformulated as Kaletra while all other RTV-containing regimens require taking RTV along with the other PI. In the case of TPV, RTV must be given as 200 mg with each dose of TPV twice per day. In contrast, ATV can be given without RTV at a dose of two 200 mg capsules once daily or 300 mg with 100 mg RTV once daily. The latter should always be used in PI-experienced subjects and when used in combination with TDF or NNRTIs which can reduce the drug levels of ATV. Similarly, FPV is also used differently in PI-naïve and experienced individuals. In treatment-naïve individuals, it can be given as two 700 mg tablets twice daily or two 700 mg tablets (1,400 mg total) with either 100 or 200 mg RTV, all once daily. In treatment-experienced patients, or when used with NNRTIs, it should be given as one 700 mg tablet with 100 mg RTV, both twice daily. The most recently approved of the PIs is DRV, which was initially used exclusively in treatment-experienced patients with drug-resistant virus. In this setting, it is given as 600 mg with 100 mg RTV, both given twice daily. More recently, DRV was approved for those who have never been treated before given at a dose of 800 mg once daily with 100 mg of RTV once daily.

Usual dosing schedule and meal restrictions for PIs
SQV+IDVNFVFPVLPV/rATVTPVDRV
SQV, saquinavir; IDV, indinavir; NFV, nelfinavir; FPV, fosamprenavir; LPV/r, lopinavir plus ritonavir; ATV, atazanavir; TPV, tipranavir; DRV, darunavir.

1Administered with RTV at a dose of 100 mg twice a day.

2FPV can be given without RTV in patients without resistance to PIs or at a dose of 1,400 mg once daily with either 100 mg or 200 mg of RTV once daily. In treatment-experienced patients, FPV is given at a dose of 700 mg twice daily with RTV 100 mg twice daily.

3ATV can be given alone at a dose of 400 mg once daily or at a dose of 300 mg once daily with RTV 100 mg or COBI 150 mg once/daily.

4TPV is always given at a dose of 500 mg twice/daily with RTV 200 mg twice daily.

5DRV can be given to those with a history of drug resistance at a dose of 600 mg twice daily with 100 mg RTV twice daily. For those without resistance, it can be given at a dose of 800 mg with 100 mg RTV or 150 mg COBI once daily.
Dose in each pill (mg)500400625700200/50200 or 300250400 or 600
Schedule21 twice a day2 every 8 hours2 twice a day2 twice a day or with RTV22 twice a day or 4 once a day2 (200) or 1 (300) with RTV or COBI3 once a day24 twice a day8005 once a day with RTV or COBI given once per day or 600 twice a day with RTV given with each dose5
Meal restrictionsWith large meals1 hour before or 2 hours after meals, or with low-fat mealsWith mealsNoneWith mealsWith mealsWith mealsWith meals

Although RTV is approved for treatment of HIV-infected patients at a dose of 600 mg twice daily, it is virtually never used at this dose because of severe side effects. Because of this, it is not included in the above table. However, PIs are frequently dosed with low doses of RTV. RTV delays the clearance of the other drugs from the system, making them easier to take and more effective. The dose of RTV varies depending upon which drugs it is being taken with and how it is being administered. The only PI that is not substantially affected by RTV is NFV. Another recently approved boosting agent is COBI which has no anti-HIV activity but can be given with once daily ATV or DRV as an alternative to RTV for pharmacologic boosting. There are also fixed-dose combinations of each, for example, ATV 300 mg combined with COBI 150 mg and DRV 800 mg combined with COBI 150 mg.

Medically Reviewed by a Doctor on 12/17/2015

Source: MedicineNet.com
http://www.medicinenet.com/human_immunodeficiency_virus_hiv/article.htm

WebMD Daily

Get breaking medical news.

advertisement
advertisement
Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations