The active ingredient saquinavir is a protease inhibitor. The drug is primarily used for the therapy of HIV infections. In this context, the substance saquinavir is mainly used in combination preparations. The drug was approved in 1995. Since a large number of patients quickly developed resistance to the drug, saquinavir was taken off the pharmaceutical market for a short time. An improved preparation has been available since 1997.
What is saquinavir?
The substance saquinavir is characterized by antiviral properties and is used for treatment against HI viruses. Saquinavir inhibits various viral processes, especially protease. This is mainly responsible for the maturation and multiplication of the viruses. It is administered orally twice a day. The tablets are taken after a meal. As a rule, the drug saquinavir is administered together with the active ingredient ritonavir. In some cases, the drug is also referred to synonymously as saquinavirum or saquinavir mesilate. In pharmaceutical use, saquinavir is present as saquinavir mesilate. This is a powder that is slightly hygroscopic and white in color. The substance is virtually insoluble in water.
Pharmacological action
Basically, the active substance saquinavir is an HIV protease inhibitor. Thus, the drug interferes with the HIV protease. This is a viral enzyme that plays a central role in the formation of new viruses. For this reason, the active ingredient saquinavir helps to delay the multiplication of the HI viruses in the human organism. If the substance saquinavir is taken alone, its bioavailability is usually too low, so that its effect is insufficient. This is because saquinavir is predominantly degraded to relatively ineffective metabolites. For this reason, the drug is nowadays usually combined with ritonavir. This is also an HIV protease inhibitor. Both active ingredients together lead to a higher concentration of the drug in the blood plasma, which significantly increases its efficacy. The active ingredient saquinavir is rapidly broken down in the liver. The cytochrome system is primarily responsible for degradation. If ritonavir is taken in parallel, this leads to a slowing of the hepatic degradation of saquinavir, so that the substance is effective for longer. In addition, in some cases the drug is combined with reverse transcriptase inhibitors. In principle, the active ingredient saquinavir leads to a reduction in viral load.
Medical application and use
Saquinavir is used in the majority of cases for the treatment of infections with HIV. In particular, the agent is used in the treatment of HIV-1-infected adults. Other antiretroviral drugs are usually used to enhance the effect of saquinavir. The corresponding therapy method is called HAART or highly active antiretroviral therapy. The dosage of the drug saquinavir takes place according to the specialist information. As a rule, it is taken in the form of tablets that are administered orally. These tablets are taken twice a day after meals. In most cases, combination therapy is carried out with the active substance ritonavir. This substance is a so-called CYP inhibitor, which slows down the metabolization of saquinavir.
Risks and side effects
Various adverse side effects and other complaints are possible in the course of therapy with saquinavir. These must be thoroughly weighed by a physician when prescribing the agent. Anamnesis, i.e. discussion of the patient’s medical history, plays a central role. This is because the attending physician analyzes the patient’s medical history as well as family dispositions. The side effects caused by the drug saquinavir occur with different frequencies. The most frequent symptoms during the intake of saquinavir are gastrointestinal complaints, such as nausea, pain in the abdominal area and diarrhea. Peripheral neuropathies and headaches are also possible. In addition to the potential side effects of saquinavir, there are some contraindications to consider before taking the drug for the first time. If the respective person suffers from hypersensitivity to the active substance saquinavir, it is mandatory to refrain from therapy with the drug.In this case, possible alternatives to treatment must be found. The drug is also contraindicated in the presence of severe hepatic insufficiency. The complete information regarding the contraindications is listed in the drug information of saquinavir. In addition, before starting therapy with saquinavir, it should be noted that various interactions with other agents exist. For example, concomitant use of pimozide, midazolam, stavudine, didanosine, efavirenz, and clarithromycin should be avoided. This is because these substances interact with the cytochrome system responsible for saquinavir degradation. As a result, changes in plasma levels occur that lead, among other things, to poorer controllability of the effect of saquinavir. Basically, saquinavir is a substrate of the substance CYP3A4. For this reason, interactions with inhibitors or inducers of CYP may occur if they are taken in parallel with saquinavir. In principle, all occurring side effects should be reported to a physician in order to decide on the further course of treatment. Discontinuation may be required if severe complications from saquinavir occur.
