April 27, 2017
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(telithromycin) Tablets



There have been reports of fatal and life-threatening respiratory failure in patients with myasthenia gravis associated with the use of KETEK. [see CONTRAINDICATIONS]


KETEK tablets contain telithromycin, a semisynthetic antibacterial in the ketolide class for oral administration. Chemically, telithromycin is designated as Erythromycin, 3-de[(2,6-dideoxy-3-C-methyl- 3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-11,12-dideoxy-6-O-methyl-3-oxo-12,11-[oxycarbonyl[[4-[4- (3-pyridinyl)-1H-imidazol-1-yl]butyl]imino]]-.

Telithromycin, a ketolide, differs chemically from the macrolide group of antibacterials by the lack of α-L-cladinose at position 3 of the erythronolide A ring, resulting in a 3-keto function. It is further characterized by a C11-12 carbamate substituted by an imidazolyl and pyridyl ring through a butyl chain. Its empirical formula is C43H65N5O10 and its molecular weight is 812.03. Telithromycin is a white to off-white crystalline powder. The following represents the chemical structure of telithromycin.

KETEK (telithromycin) Structural Formula Illustration

KETEK tablets are available as light-orange, oval, film-coated tablets, each containing 400 mg or 300 mg of telithromycin, and the following inactive ingredients: croscarmellose sodium, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone, red ferric oxide, talc, titanium dioxide, and yellow ferric oxide.

What are the possible side effects of telithromycin (Ketek, Ketek Pak)?

Telithromycin may cause sudden and serious liver damage. In rare cases, liver failure can develop and may cause death. Stop using the medication and call your doctor right away if you have nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using telithromycin and call your doctor at once if you have a serious side...

Read All Potential Side Effects and See Pictures of Ketek »

What are the precautions when taking telithromycin (Ketek)?

Before taking telithromycin, tell your doctor or pharmacist if you are allergic to it; or to macrolide antibiotics (e.g., azithromycin, clarithromycin, dirithromycin, erythromycin); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: myasthenia gravis, severe kidney disease (including dialysis), liver problems (such as hepatitis, especially if it occurred while taking telithromycin or a macrolide antibiotic).

Telithromycin may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely...

Read All Potential Precautions of Ketek »

Last reviewed on RxList: 5/19/2016
This monograph has been modified to include the generic and brand name in many instances.

Ketek - User Reviews

Ketek User Reviews

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Here is a collection of user reviews for the medication Ketek sorted by most helpful. Patient Discussions FAQs

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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