An older HIV medicine (a boosted protease inhibitor)
Saquinavir
An older HIV protease inhibitor, always given boosted, now rarely used partly because it can affect the heart's electrical rhythm.
What is Saquinavir?
Saquinavir is an older HIV medicine called a protease inhibitor. It was used as part of combination therapy, always with other HIV medicines and never on its own, and it is always boosted with a small amount of ritonavir. It is now rarely used, partly because it can affect the heart's electrical rhythm (prolonging the QT and PR intervals), which means an ECG heart tracing may be needed and certain combinations must be avoided. It also interacts with many other medicines. Newer protease inhibitors are preferred in the UK.
Education and reference only. This is a plain-language guide to Saquinavir — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Saquinavir is an antiretroviral medicine used to treat HIV. It belongs to a group called protease inhibitors. Like all HIV medicines, it is only ever used as part of combination therapy, alongside other antiretrovirals and never on its own, because a single HIV medicine used alone lets the virus become resistant. It is always given boosted with a small amount of ritonavir, which raises its levels so it works properly. It is taken by mouth. It is now rarely used in the UK, in part because of its effects on the heart's rhythm and its many interactions, with newer protease inhibitors generally preferred.
How it works
HIV uses an enzyme called protease to put together new, infectious copies of the virus. Saquinavir blocks this enzyme, so the virus makes only faulty particles that cannot infect new cells, helping keep the amount of virus down. Because HIV can become resistant to any single medicine, saquinavir works as part of a combination that attacks the virus in different ways. It is always boosted with ritonavir, which slows its breakdown so its levels stay high enough to work. One reason it is now seldom used is that it can affect the heart's electrical signalling, prolonging the QT and PR intervals.
Company & origin
Originated / developed by: Specialist manufacturer.
An older HIV medicine used in the UK as part of combination therapy; now rarely used, partly because it can affect the heart's rhythm.
Practical use
How to take Saquinavir
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth exactly as prescribed, always together with the other HIV medicines in your combination, never on its own.
- Always take it with the boosting medicine ritonavir, as it does not work properly on its own.
- Take it consistently and on time, as missing doses can let the virus become resistant.
- Tell your prescriber about any heart-rhythm problems and give a full list of your other medicines.
- Attend for any ECG heart tracings and blood tests your specialist team arranges.
Weighing it up
Advantages & disadvantages of Saquinavir
Advantages
- An effective HIV protease inhibitor in its time, helping suppress the virus as part of combination therapy.
- Taken by mouth when boosted with ritonavir.
- Was one of the earlier protease inhibitors in HIV treatment.
Disadvantages
- Can affect the heart's electrical rhythm (prolonging the QT and PR intervals), needing ECG checks.
- Interacts with many medicines and cannot be combined with several others.
- Must always be boosted and is now rarely used, as newer options are preferred.
Practical use
Good to know
The most important safety point with saquinavir is that it can affect the heart's electrical rhythm, prolonging what are called the QT and PR intervals; this means a heart tracing (ECG) may be done before and during treatment, and it cannot be combined with various other medicines that have the same effect. It must always be boosted with ritonavir and is never used at full effect without it. Like other protease inhibitors, it interacts with a wide range of medicines and can affect blood fats and blood sugar. It must always be taken as part of a combination, consistently and on time, to keep the virus under control. Because of these issues, newer protease inhibitors are usually preferred. HIV care is provided by a specialist team.
Who should not take it / use with caution
- People who have had a serious allergic reaction to saquinavir should not take it.
- It is avoided in people with certain heart-rhythm problems or those taking other medicines that affect the heart's rhythm.
- It is used with caution in liver problems, and only under specialist care as part of a boosted combination.
Monitoring
- Regular blood tests including the amount of virus (viral load), immune cells (CD4 count) and liver function.
- ECG heart tracings to check the QT and PR intervals before and during treatment.
- Reviewing blood fats, blood sugar, other medicines and the overall HIV combination.
Side effects
- Changes in the heart's electrical rhythm (prolonged QT or PR interval).
- Nausea, diarrhoea or other stomach upset.
- Changes in blood fats and blood sugar, and changes in body fat over time.
- Headache or tiredness in some people.
Key interactions
- It must not be combined with medicines that also prolong the heart's QT interval, because of the risk of dangerous rhythm problems.
- It interacts with many medicines, raising or lowering their levels, so a full medicines list is essential.
- It is always given with ritonavir, and the combination is chosen carefully to avoid harmful overlaps.
Available as: Capsules and tablets taken by mouth, always boosted with ritonavir.
Answers
Saquinavir: frequently asked questions
What is saquinavir used for?
It is an older HIV protease inhibitor used as part of combination therapy to help keep the virus suppressed; it is always used with other HIV medicines, never alone.
Why might I need an ECG?
Saquinavir can affect the heart's electrical rhythm (the QT and PR intervals), so an ECG heart tracing may be done before and during treatment to check it is safe.
Why is it always given with ritonavir?
Saquinavir does not reach high enough levels on its own, so a small amount of ritonavir boosts it so it works properly.
Why is it now rarely used?
Its effect on the heart's rhythm and its many interactions, together with the arrival of newer protease inhibitors, mean it is seldom chosen today.
Can it be taken on its own?
No. Like all HIV medicines it must be part of a combination, because using one HIV medicine alone lets the virus become resistant.
The wider class
About Antiretroviral (protease inhibitor) for HIV
Saquinavir belongs to the antiretroviral (protease inhibitor) for hiv class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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