KETEK

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KETEK (KETEK).

How it works

Telithromycin binds to the 50S subunit of bacterial ribosome, inhibiting protein synthesis by blocking peptide chain elongation.

What the body does with it

Metabolism	Metabolized primarily by CYP3A4 and to a lesser extent by CYP1A2. Undergoes first-pass metabolism.
Excretion	Primarily fecal (≈70%) via biliary excretion of unchanged drug; renal excretion accounts for ≈13% (mostly unchanged), with additional minor metabolism (<30%).
Half-life	Terminal half-life (t½) is 9.8–10.6 hours in young healthy adults, allowing once-daily dosing. In elderly or severe hepatic impairment, t½ may be prolonged.
Protein binding	Serum protein binding ≈60–70%, primarily to albumin and α1-acid glycoprotein.
Volume of Distribution	Volume of distribution (Vd) ≈2.5–3 L/kg, indicating extensive tissue penetration (high intracellular concentrations).
Bioavailability	Oral bioavailability ≈57% (increases by ≈40% with food; take with food to enhance absorption).
Onset of Action	Oral: Time to maximum plasma concentration (Tmax) 0.5–3 hours; clinical effect (e.g., symptom improvement in respiratory infections) typically within 24–48 hours.
Duration of Action	Once-daily dosing (800 mg) maintains therapeutic concentrations over 24 hours due to long half-life and post-antibiotic effect. Duration of clinical effect continues for entire dosing interval.

Classification & Brands

Dosing & administration

Telithromycin 800 mg orally once daily for 7-10 days.

Dosage form	TABLET
Renal impairment	CrCl >=30 mL/min: no adjustment; CrCl <30 mL/min: 400 mg orally once daily.
Liver impairment	Child-Pugh A or B: no adjustment; Child-Pugh C: contraindicated.
Pediatric use	Not approved for use in pediatric patients.
Geriatric use	No specific dose adjustment recommended; monitor for adverse effects and drug interactions.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KETEK (KETEK).

Breastfeeding	Excretion into human milk unknown; M/P ratio not established. Due to potential for adverse effects in nursing infants (e.g., gastrointestinal disturbances, hepatotoxicity), caution advised. Use only if clearly needed.
Teratogenic Risk	Telithromycin is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and fetotoxicity at doses 2-4 times the human dose. No adequate human studies exist; risk cannot be ruled out. Avoid use in first trimester unless benefit outweighs risk.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

Telithromycin is contraindicated in patients with myasthenia gravis due to risk of rapid onset of respiratory failure or death. Fatal and life-threatening respiratory failure has been reported in myasthenia gravis patients.

Side Effect Profile

Serious Effects

Absolute Contraindications

History of hypersensitivity to telithromycin or any macrolide antibiotic, myasthenia gravis, concomitant use with pimozide, cisapride, ergotamine, or other CYP3A4 substrates with narrow therapeutic index, previous cholestatic jaundice or hepatic dysfunction with telithromycin.

Clinical Precautions

Precautions

Hepatotoxicity (including severe liver injury and fatalities), exacerbation of myasthenia gravis, QT interval prolongation, visual disturbances (loss of consciousness, blurred vision, diplopia), Clostridium difficile-associated diarrhea, and potential for drug interactions with CYP3A4 substrates.

Clinical Tips & Counseling

Drug interactions

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KETEK

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KETEK (KETEK).

How it works

Telithromycin binds to the 50S subunit of bacterial ribosome, inhibiting protein synthesis by blocking peptide chain elongation.

What the body does with it

Metabolism	Metabolized primarily by CYP3A4 and to a lesser extent by CYP1A2. Undergoes first-pass metabolism.
Excretion	Primarily fecal (≈70%) via biliary excretion of unchanged drug; renal excretion accounts for ≈13% (mostly unchanged), with additional minor metabolism (<30%).
Half-life	Terminal half-life (t½) is 9.8–10.6 hours in young healthy adults, allowing once-daily dosing. In elderly or severe hepatic impairment, t½ may be prolonged.
Protein binding	Serum protein binding ≈60–70%, primarily to albumin and α1-acid glycoprotein.
Volume of Distribution	Volume of distribution (Vd) ≈2.5–3 L/kg, indicating extensive tissue penetration (high intracellular concentrations).
Bioavailability	Oral bioavailability ≈57% (increases by ≈40% with food; take with food to enhance absorption).
Onset of Action	Oral: Time to maximum plasma concentration (Tmax) 0.5–3 hours; clinical effect (e.g., symptom improvement in respiratory infections) typically within 24–48 hours.
Duration of Action	Once-daily dosing (800 mg) maintains therapeutic concentrations over 24 hours due to long half-life and post-antibiotic effect. Duration of clinical effect continues for entire dosing interval.

Classification & Brands

Dosing & administration

Telithromycin 800 mg orally once daily for 7-10 days.

Dosage form	TABLET
Renal impairment	CrCl >=30 mL/min: no adjustment; CrCl <30 mL/min: 400 mg orally once daily.
Liver impairment	Child-Pugh A or B: no adjustment; Child-Pugh C: contraindicated.
Pediatric use	Not approved for use in pediatric patients.
Geriatric use	No specific dose adjustment recommended; monitor for adverse effects and drug interactions.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KETEK (KETEK).

Breastfeeding	Excretion into human milk unknown; M/P ratio not established. Due to potential for adverse effects in nursing infants (e.g., gastrointestinal disturbances, hepatotoxicity), caution advised. Use only if clearly needed.
Teratogenic Risk	Telithromycin is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and fetotoxicity at doses 2-4 times the human dose. No adequate human studies exist; risk cannot be ruled out. Avoid use in first trimester unless benefit outweighs risk.
Fetal Monitoring