What is Invirase?
Invirase is a medicine containing the active substance saquinavir. It is available as brown and green capsules (200 mg) and orange oval tablets (500 mg).
What is Invirase used for?
Invirase is an antiviral drug. It is used to treat adults with human immunodeficiency virus type 1 (HIV-1) infection, a virus that causes acquired immune deficiency syndrome (AIDS). Invirase is always used in combination with ritonavir (another antiviral medicine) and other antiviral medicines.
The medicine can only be obtained with a prescription.
How is Invirase used?
Invirase therapy should be started by a doctor who specializes in treating HIV infection. INVIRASE should always be given in combination with other antiviral medicines. The recommended dose of Invirase for adults and adolescents over the age of 16 is 1, 000 mg twice a day (with ritonavir 100 mg), during or after a meal. Invirase should be used with caution in patients with severe renal impairment or moderate hepatic impairment. The medicine should not be used in patients with severe hepatic impairment.
How does Invirase work?
The active substance in Invirase, saquinavir, is a protease inhibitor. It blocks an enzyme, protease, which is involved in the reproduction of HIV. If the enzyme is blocked, the virus is unable to reproduce normally and the infection is slowed down. Ritonavir is another protease inhibitor which is used to increase the potency of another drug (pharmacokinetic enhancer or "booster"). It slows down the rate at which saquinavir is assimilated, thereby increasing its concentration in the blood. This allows a lower dose of saquinavir to be used for the same antiviral effect. Taken in combination with other antiviral drugs, Invirase reduces the amount of HIV in the blood and keeps it at a low level. Invirase does not cure HIV infection or AIDS, but it may delay the damage to the immune system and the development of infections and diseases associated with AIDS.
What studies have been carried out on Invirase?
Invirase has been studied in six main studies involving 1 576 patients. The first four studies evaluated the effects of the medicine without ritonavir. The combination of Invirase with ritonavir has been studied in 656 patients in two studies that compared Invirase to indinavir and lopinavir (other antiviral medicines), both in combination with ritonavir and other antiviral medicines. These studies measured the number of patients whose treatment stopped being effective after 48 weeks, caused by an increase in the level of HIV in the blood (viral load).
What benefit has Invirase shown during the studies?
Invirase, taken in combination with other antiviral medicines, has led to a reduction in viral load and improvements in the immune system. In Invirase studies in combination with ritonavir, Invirase had similar rates of therapy similar to those of indinavir, but higher than lopinavir. This phenomenon was mainly caused by a higher number of patients who stopped treatment with Invirase than by differences in the efficacy of the medicines.
What is the risk associated with Invirase?
The most common adverse reactions of Invirase in combination with ritonavir (seen in more than 1 patient in 10) are diarrhea, nausea, higher levels of liver enzymes, cholesterol and triglycerides (type of fat) in the blood, and lower levels of blood platelets (components that contribute to blood clotting). For the full list of all side effects reported with Invirase, see the Package Leaflet.
Invirase should not be used in people who may be hypersensitive (allergic) to saquinavir or any of the other ingredients (components). It must not be used in patients with severe hepatic impairment or being treated with any of the following drugs:
- terfenadine, astemizole (usually used to treat allergy symptoms; these medicines can be purchased without a prescription);
- pimozide (for the treatment of mental illnesses);
- cisapride (for the treatment of stomach disorders);
- amiodarone, propafenone, flecainide (used to correct cardiac arrhythmias);
- triazolam, oral midazolam (used for the treatment of anxiety or sleep disorders);
- simvastatin, lovastatin (used to lower blood cholesterol levels);
- ergot alkaloids, such as ergotamine, dihydroergotamine, ergonovine and methylergonovine (used to treat migraine);
- rifampicin (for the treatment of tuberculosis);
- medicines that may interact with Invirase and cause harmful side effects.
Care should be taken if Invirase is taken at the same time as other medicines. For a detailed description, see the package leaflet.
As with other anti-HIV drugs, patients receiving Invirase may be at risk of lipodystrophy (changes in the distribution of body fat), osteonecrosis (death of bone tissue) or immune reactivation syndrome (symptoms of infections caused by the reactivation of the immune system ). Patients with liver disease (including hepatitis B or C infection) may be at an increased risk of developing liver damage when treated with Invirase.
Why has Invirase been approved?
The Committee for Medicinal Products for Human Use (CHMP) decided that Invirase's benefits, in combination with other antiretroviral medicines, outweigh its risks in the treatment of adult patients with HIV-1 infection. The committee recommended the granting of the marketing authorization for Invirase.
Originally Invirase had been authorized "in exceptional circumstances" because, for scientific reasons, the data available at the time of approval were limited. As the company provided the additional information requested, the condition referring to "exceptional circumstances" was removed on 8 April 1999.
Other information on Invirase:
On 4 October 1996, the European Commission granted a marketing authorization for INVIRASE, valid throughout the European Union, to Roche Registration Limited. This authorization was renewed on 4 October 2001 and 4 October 2006.
The full EPAR for Invirase can be found here.
Last update of this summary: 11-2008.
