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Saquinavir structure.svg
Saquinavir ball-and-stick.png
Systematic (IUPAC) name
Clinical data
Trade names Invirase, Fortovase
AHFS/ monograph
MedlinePlus a696001
  • B1 (Australia)
Pharmacokinetic data
Bioavailability ~4% (without ritonavir boosting)[1]
Protein binding 98%
Metabolism Hepatic, mainly by CYP3A4
Biological half-life 9–15 hours
Excretion feces (81%) and urine (3%)
CAS Number 127779-20-8 YesY
ATC code J05AE01
PubChem CID: 441243
DrugBank DB01232 YesY
ChemSpider 390016 YesY
KEGG D00429 YesY
NIAID ChemDB 000640
Chemical data
Formula C38H50N6O5
Molecular mass 670.841 g/mol
 YesY (what is this?)  (verify)

Saquinavir, sold under the brand names Invirase and Fortovase, is an antiretroviral drug used together with other medications to treat or prevent HIV/AIDS.[2] Typically it is used with ritonavir or lopinavir/ritonavir. It is taken by mouth.[2]

Common side effects include nausea, vomiting, diarrhea, and feeling tired. More serious side effects include problems with QT prolongation, heart block, high blood lipids, and liver problems. It appears to be safe in pregnancy. It is in the protease inhibitor class and works by blocking the HIV protease.[2]

Saquinavir was first sold in 1995.[3] It is on the World Health Organization's List of Essential Medicines, the most important medication needed in a basic health system.[4] As of 2015 it is not available as a generic medication and is expensive.[5] The wholesale cost is about 4.50 USD per day.[6]

Medical uses[edit]

Saquinavir is used together with other medications to treat or prevent HIV/AIDS.[2] Typically it is used with ritonavir or lopinavir/ritonavir.[2]

Side effects[edit]

The most frequent adverse events with saquinavir in either formulation are mild gastrointestinal symptoms, including diarrhea, nausea, loose stools & abdominal discomfort. Invirase is better tolerated than Fortovase.

Bioavailability and drug interactions[edit]

Saquinavir, in the Invirase formulation, has a low and variable oral bioavailability, when given alone. The Fortovase formulation at the standard dosage delivers approximately eightfold more active drug than Invirase, also at the standard dosage.[7]

In the clinic, it was found that the oral bioavailability of saquinavir in both formulations significantly increases when patients also receive the PI ritonavir. For patients, this has the major benefit that they can take less saquinavir, while maintaining sufficient saquinavir blood plasma levels to efficiently suppress the replication of HIV.

The mechanism behind this welcome observation was not directly known, but later it was determined that ritonavir inhibits the cytochrome P450 3A4 isozyme. Normally, this enzyme metabolizes saquinavir to an inactive form, but with the ritonavir inhibiting this enzyme, the saquinavir blood plasma levels increased considerably. Additionally, ritonavir also inhibits multidrug transporters, although to a much lower extent.

Unlike other protease inhibitors, the absorption of saquinavir seems to be improved by omeprazole.[8]

Mechanism of action[edit]

Saquinavir is a protease inhibitor. Proteases are enzymes that cleave protein molecules into smaller fragments. HIV protease is vital for both viral replication within the cell and release of mature viral particles from an infected cell. Saquinavir binds to the active site of the viral protease and prevents cleavage of viral polyproteins, preventing maturation of the virus. Saquinavir inhibits both HIV-1 and HIV-2 proteases.


United States HIV new infections and HIV deaths before and after the FDA approval of saquinavir.
HIV deaths in the United States fell from approximately 50,000 per year to 18,000 in the two years following the FDA approval of saquinavir[9]

Saquinavir was developed by the pharmaceutical company Roche. Saquinavir was the first protease inhibitor (and sixth antiretroviral) approved by the Food and Drug Administration (FDA). Within 2 years of its approval, and that of ritonavir 4 months later, annual deaths from AIDS in the United States fell from over 50,000 to approximately 18,000.[10] The manufacturer, Roche, requested and received approval of Invirase via the FDA's "Accelerated Approval" program, a process designed to speed drugs to market for the treatment of serious diseases. This decision was controversial, amid disagreement between AIDS activists over the benefits of thorough testing versus early access to new drugs.[11]

It was approved again on Nov 7, 1997 as Fortovase, a soft gel capsule reformulated for improved bioavailability. Roche announced in May 2005 that, owing to reduction in demand, Fortovase would cease being marketed early in 2006 in favour of Invirase boosted with ritonavir.[12]

Society and culture[edit]


As of 2015 it is not available as a generic medication and is expensive.[5] The wholesale cost is about 4.50 USD per day.[6]


Two formulations have been marketed:

  • a hard-gel capsule formulation of the mesylate, with trade name Invirase, which requires combination with ritonavir to increase the saquinavir bioavailability;
  • a soft-gel capsule formulation of saquinavir (microemulsion,[13] orally-administered formulation), with trade name Fortovase, which was discontinued worldwide in 2006.[14]


  1. ^ "Invirase (saquinavir mesylate) Capsules and Tablets, for Oral Use. Full Prescribing Information" (PDF). Genentech, Inc. Retrieved 23 November 2015. 
  2. ^ a b c d e "Saquinavir". The American Society of Health-System Pharmacists. Retrieved Sep 5, 2015. 
  3. ^ Minor, Lisa K. (2006). Handbook of Assay Development in Drug Discovery. Hoboken: CRC Press. p. 117. ISBN 9781420015706. 
  4. ^ "WHO Model List of Essential Medicines" (PDF). World Health Organization. October 2013. Retrieved 22 April 2014. 
  5. ^ a b Hamilton, Richart (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 72. ISBN 9781284057560. 
  6. ^ a b "Saquinavir". International Drug Price Indicator Guide. Retrieved 6 September 2015. 
  7. ^ FortovaseTM (saquinavir) soft gelatin capsules. Product information (November 1997)
  8. ^ Winston A, Back D, Fletcher C, et al. (2006). "Effect of omeprazole on the pharmacokinetics of saquinavir-500 mg formulation with ritonavir in healthy male and female volunteers". AIDS 20 (10): 1401–6. doi:10.1097/01.aids.0000233573.41597.8a. PMID 16791014. 
  9. ^ "" (PDF). 
  10. ^ "HIV Surveillance --- United States, 1981--2008". Retrieved 8 November 2013. 
  11. ^ "Drugs! Drugs! Drugs! An Overview of the Approved Anti-HIV Medications". The Body. Retrieved 20 February 2013. 
  12. ^ Withdrawal of Fortovase (PDF)
  13. ^ Gibaud, S. P.; Attivi, D. (2012). "Microemulsions for oral administration and their therapeutic applications". Expert Opinion on Drug Delivery: 1. doi:10.1517/17425247.2012.694865. 
  14. ^ News-Medical.Net. May 18, 2005 Roche to discontinue the sale and distribution of Fortovase (saquinavir)

External links[edit]