Invirase (saquinavir)

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting, indigestion or abdominal pain

Headache

Difficulty in sleeping (insomnia)

Depression

Anxiety

Fatigue

Chest pain

Changes in sex drive

Alteration in taste

Fever (pyrexia)

Mouth ulcers

Skin reactions such as rash and itch

Dizziness

Pins and needles (paraesthesia)

Disorder of the peripheral nerves causing weakness and numbness (peripheral neuropathy)

Weakness or loss of strength (asthenia)

Pain

Liver disorders

Inflammation of the pancreas (pancreatitis)

Kidney stones

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

As saquinavir is used in combination with ritonavir, your doctor or pharmacist will also check whether any of your medicines interact with ritonavir .

The following medicines must not be used in combination with saquinavir, as there may be a risk of severe side effects:

amiodarone

astemizole

cisapride

ergot alkaloids (eg ergotamine, dihydroergotamine, ergonovine, and methylergonovine)

flecainide

lovastatin

midazolam

pimozide

propafenone

rifampicin

simvastatin

terfenadine

triazolam.

You should not take garlic capsules or the herbal remedy St John's wort (Hypericum perforatum) with this medicine, as they may decrease the blood level of saquinavir and make it less effective.

Oestrogen-containing oral contraceptives may be less effective in women who are taking saquinavir and ritonavir. For this reason, the manufacturer recommends that women using oestrogen-containing oral contraceptives should use an additional method of contraception to prevent pregnancy, or use a different method of contraception altogether. Ask your doctor for advice.

Saquinavir may increase the blood levels of the following medicines used for erectile dysfunction:

sildenafil (Viagra) (do not take more than 25mg in 48 hours while taking saquinavir)

vardenafil (Levitra) (do not take more than 2.5 mg in 72 hours while taking saquinavir)

tadalafil (Cialis) do not take more than 10 mg in 72 hours while taking saquinavir).

Saquinavir may increase the blood level of atorvastatin (used for lowering cholesterol levels). As this may increase the risk of side effects on the muscles, it should be used with caution in people taking saquinavir. If a statin medicine is needed to lower cholesterol levels, pravastatin or fluvastatin is a prefered option.

Saquinavir and ritonavir may increase the blood levels of benzodiazepines such as diazepam, alprazolam, clorazepate and flurazapem. If you are taking one of these together with saquinavir/ritonavir you should let your doctor know if you feel excessively sleepy or drowsy.

Saquinavir and ritonavir may increase the blood levels of calcium channel blockers such as felodipine, nifedipine, nicardipine, diltiazem, nimodipine, verapamil, amlodipine, nisoldipine and isradipine. If you are taking one of these together with saquinavir/ritonavir you should let your doctor know if you get any new or worsening side effects.

Saquinavir and ritonavir may increase the blood levels of immunosuppressants ciclosporin, sirolimus and tacrolimus. If you are taking one of these together with saquinavir/ritonavir your doctor may want to monitor the blood level of the immunosuppressant.

Saquinavir with ritonavir also increases the blood level of the corticosteroids fluticasone and budesonide taken by inhaler or nasal spray. This could increase the risk of systemic side effects of these steroids, such as Cushing's syndrome, or decreased production of natural steroids by the adrenal glands. For this reason, the use of these corticosteroids in combination with saquinavir and ritonavir is not recommended, unless the benefits are thought to outweigh the potential risks.

Saquinavir may increase the blood level of tricyclic antidepressants such as amitriptyline and imipramine. If you are taking one of these with saquinavir/ritonavir your doctor may want to perform additional monitoring.

Saquinavir may increase the blood level of digoxin. If you are taking digoxin together with saquinavir/ritonavir your doctor may want to monitor your blood level of digoxin so your dose can be adjusted if necessary.

Saquinavir may increase the anti-blood-clotting effect of warfarin. People who are taking warfarin with saquinavir should have their blood-clotting time (INR) monitored.

When saquinavir and ritonavir are used in combination with the anti-HIV medicine efavirenz, there may be an increased risk of side effects on the liver. If you are taking these three medicines to treat HIV infection your liver function should be regularly checked.

The following medicines may increase the blood level of saquinavir. If you are prescribed any of these while taking saquinavir you should let your doctor know if you get any new or worsening side effects:

delavirdine (extra monitoring of liver function should be performed if saquinavir is used with delavirdine)

indinavir

nelfinavir

clarithromycin

erythromycin

itraconazole

ketoconazole

nefazodone

omeprazole.

The following medicines may decrease the blood level of saquinavir and may therefore make it less effective:

carbamazepine

dexamethasone

phenobarbital

phenytoin

rifabutin (saquinavir may also increase the blood level of rifabutin)

tipranavir (not recommended in combination with saquinavir/ritonavir).

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain saquinavir as the active ingredient.

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