Ketek (telithromycin)

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, nausea, vomiting, abdominal pain, flatulence or constipation.
- Headache.
- Dizziness.
- Alteration in taste.
- Vaginal or oral thrush (candidiasis).
- Alteration in results of liver function tests.
- Loss of appetite.
- Inflammation of the lining of the mouth (stomatitis).
- Sleepiness (somnolence).
- Difficulty in sleeping (insomnia).
- Nervousness.
- Blurred or double vision.
- Rash or itching.
- Flushing.
- Awareness of your heartbeat (palpitations).
- Jaundice.
- Abnormal heart beats (arrhythmias).
- Low blood pressure (hypotension).
- Temporary loss of conciousness (fainting).
- Inflammation of the liver (hepatitis).

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, ask your doctor or pharmacist before taking any new medicines while taking this one, so they can check that the combination is safe.

Telithromycin must not be taken by people taking any of the following medicines, because the combination may result in an increased risk of serious side effects:

- astemizole
- cisapride
- ergot alkaloids, eg ergotamine, dihydroergotamine, methysergide
- pimozide
- terfenadine.

Telithromycin may increase the blood levels of statins used for lowering cholesterol and this could increase the risk of side effects from the statin. If you are taking simvastatin, lovastatin or atorvastatin you will need to stop taking it during treatment with this antibiotic and restart it again after the antibiotic course is completed. If you are taking another statin, eg cerivastatin, you can continue taking it while taking this antibiotic, but you should let your doctor know if you get any new or increased side effects, in particular any muscle pain or weakness.

Telithromycin may also increase the blood levels of the medicines listed below and so could increase the risk of their side effects.

- Digoxin. If you are taking digoxin your doctor may want to monitor your digoxin blood level while you are taking this antibiotic.
- Metoprolol.
- The benzodiazepines midazolam, triazolam and alprazolam. (Midazolam should not be taken by mouth by people taking this antibiotic.)
- The immunosuppressants ciclosporin, tacrolimus and sirolimus. If you are taking any of these your doctor will need to check your blood level of the immunosuppressant when you start taking this antibiotic and after the course is finished. Your immunosuppressant dose may need adjusting.

Telithromycin should ideally not be used to treat people taking any of the following medicines, or who have taken any of these in the previous two weeks, because they may make the antibiotic less effective:

- carbamazepine
- phenobarbitone (phenobarbital)
- phenytoin
- rifampicin
- the herbal remedy St John's wort (Hypericum perforatum).

Telithromycin may increase the anti-blood-clotting effect of anticoagulants such as warfarin. If you are taking an anticoagulant medicine your doctor may want to do extra monitoring of your blood clotting time (INR) while you are taking this antibiotic.

Protease inhibitors for treating HIV infection, such as ritonavir, may increase the blood level of telithromycin. As this may increase the risk of its side effects, telithromycin should be used with caution in people taking protease inhibitors. If you have severe liver or kidney disease and are taking a protease inhibitor, you should not be prescribed telithromycin.

Anitfungal medicines such as ketoconazole may also increase the blood level of telithromycin. They should not be used in combination with telithromycin in people who have severe liver or kidney disease.

Telithromycin should be used with caution in people taking any of the following medicines, because the combination may increase the risk of abnormal heart rhythms (prolonged QT interval on the heart monitoring trace or ECG):

- anti-arrhythmics, eg amiodarone, procainamide, disopyramide, sotalol
- antidepressants, eg amitriptyline, imipramine, maprotiline
- antimalarials, eg halofantrine, chloroquine, quinine
- antipsychotics, eg thioridazine, chlorpromazine, sertindole, haloperidol
- atomoxetine
- the antibiotics erythromycin or pentamidine given by injection into a vein.

If you are taking theophylline in combination with this antibiotic, your doses of the two medicines should be separated by one hour. This is to avoid possible digestive side effects such as nausea and vomiting.

If you are taking a combined oral contraceptive pill or are using contraceptive patches, there may be a very low risk that this antibiotic may make it less effective at preventing pregnancy. Although the risk of this is very low, the personal and ethical consequences of an unwanted pregnancy can be very serious. For this reason, the Family Planning Association recommends that women using a combined contraceptive pill or patch should use an extra method of contraception (eg condoms) while taking a short course of broad-spectrum antibiotic, and for seven days after finishing the course. If the seven days run beyond the end of a pill packet, a new packet should be started without a break (in the case of ED pills the inactive tablets should be omitted). If the seven days run beyond the 3 weeks of patch treatment, a new treatment cycle should be started immediately without a patch-free break.

Other medicines containing the same active ingredient

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

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