indication

For the treatment of Pneumococcal infection, acute sinusitis, acute bacterial tonsillitis, acute bronchitis and bronchiolitis, lower respiratory tract infection and lobar (pneumococcal) pneumonia.

pharmacology

Telithromycin is a ketolide antibiotic which has an antimicrobial spectrum similar or slightly broader than that of penicillin. It is often used as an alternative in patients who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma. Telithromycin prevents bacterial growth by binding to bacterial 50S ribosomal subunits and interfering with bacterial peptide translocation and elongation.

mechanism of action

Telithromycin acts by binding to domains II and V of 23S rRNA of the 50S ribosomal subunit. By binding at domain II, telithromycin retains activity against gram-positive cocci (e.g. Streptococcus pneumoniae) in the presence of resistance mediated by methylases (erm genes) that alter the binding site at domain V. Telithromycin may also inhibit the assembly of nascent ribosomal units. Compared to erythromycin A, telithromycin binds to the 23S rRNA with 10 times greater affinity in erythromycin-susceptible organisms and 25 times greater affinity in macrolide-resistant strains. This increased binding affinity may be conferred by the C11-12 carbamate side chain of telithromycin. The side chain appears to maintain binding at domain II in the presence of resistance mediated by alterations in domain V.

toxicity

LD50>2000 mg/kg (PO in rats). Adverse effects are similar to those of clarithormycin and erithromycin and include diarrhea, nausea, vomiting, loose stools, abdominal pain, flatulence and dyspepsia. It may also cause dizziness, headache and taste disturbances.

biotransformation

Hepatic - estimated 50% metabolized by CYP3A4 and 50% metabolized independent of cytochrome P450

absorption

Absolute bioavailability is approximately 57%. Maximal concentrations are reached 0.5 - 4 hours following oral administration. Food intake does not affected absorption.

half life

Main elimination half-life is 2-3 hours; terminal elimination half-life is 10 hours

route of elimination

The systemically available telithromycin is eliminated by multiple pathways as follows: 7% of the dose is excreted unchanged in feces by biliary and/or intestinal secretion; 13% of the dose is excreted unchanged in urine by renal excretion; and 37% of the dose is metabolized by the liver.

drug interactions

Acenocoumarol: Telithromycin may increase the anticoagulant effect of acenocoumarol.

Alfentanil: Telithromycin may reduce clearance of Alfentanil. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Alfentanil if Telithromycin is initiated, discontinued or dose changed.

Alfuzosin: Telithromycin may reduce clearance of Alfuzosin. Consider alternate therapy.

Alprazolam: Telithromycin may increase the effect and toxicity of the benzodiazepine, alprazolam.

Aminoglutethimide: Aminoglutethimide may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Amiodarone: Telithromycin may reduce clearance of Amiodarone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Amiodarone if Telithromycin is initiated, discontinued or dose changed.

Amlodipine: Telithromycin may reduce clearance of Amlopidine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Amlopidine if Telithromycin is initiated, discontinued or dose changed.

Amprenavir: Co-administration may result in altered plasma concentrations of Amprenavir and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Anisindione: Telithromycin may increase the anticoagulant effect of anisindione.

Aprepitant: Telithromycin may reduce clearance of Aprepitant. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Aprepitant if Telithromycin is initiated, discontinued or dose changed.

Aripiprazole: Telithromycin may reduce clearance of Aripiprazole. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Aripiprazole if Telithromycin is initiated, discontinued or dose changed.

Artemether: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Astemizole: Increased risk of cardiotoxicity and arrhythmias

Atazanavir: Co-administration may result in altered plasma concentrations of Atazanavir and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Atorvastatin: The macrolide antibiotic, telithromycin, may increase the serum concentration of atorvastatin by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of atorvastatin if telithromycin is initiated, discontinued or dose changed.

Benzphetamine: Telithromycin may reduce clearance of Benzphetamine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Benzphetamine if Telithromycin is initiated, discontinued or dose changed.

Bisoprolol: Telithromycin may reduce clearance of Bisoprolol. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Bisoprolol if Telithromycin is initiated, discontinued or dose changed.

Bortezomib: Telithromycin may reduce clearance of Bortezomib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Bortezomib if Telithromycin is initiated, discontinued or dose changed.

Bosentan: Co-administration may cause decreased Telithromycin and increased Bosentan plasma concentrations. Consider alternate therapy.

Bretylium: Increased risk of cardiotoxicity and arrhythmias

Bromazepam: Telithromycin, a strong CYP3A4 inhibitor, may increase the serum concentration of bromazepam by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of bromazepam if telithromycin is initiated, discontinued or dose changed. Dosage adjustments may be required.

Bromocriptine: Telithromycin may reduce clearance of Bromocriptine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Bromocriptine if Telithromycin is initiated, discontinued or dose changed.

Budesonide: Telithromycin may reduce clearance of Budesonide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Budesonide if Telithromycin is initiated, discontinued or dose changed.

Buprenorphine: Telithromycin may reduce clearance of Buprenorphine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Buprenorphine if Telithromycin is initiated, discontinued or dose changed.

Buspirone: Telithromycin may reduce clearance of Buspirone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Buspirone if Telithromycin is initiated, discontinued or dose changed.

Busulfan: Telithromycin may reduce clearance of Busulfan. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Busulfan if Telithromycin is initiated, discontinued or dose changed.

Calcitriol: Telithromycin may reduce clearance of Calcitriol. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Calcitriol if Telithromycin is initiated, discontinued or dose changed.

Carbamazepine: Co-administration may cause decreased Telithromycin and increased Carbemazepine plasma concentrations. Consider alternate therapy.

Chlordiazepoxide: Telithromycin may reduce clearance of Chlordiazepoxide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Chlordiazepoxide if Telithromycin is initiated, discontinued or dose changed.

Chloroquine: Telithromycin may reduce clearance of Chloroquine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Chloroquine if Telithromycin is initiated, discontinued or dose changed.

Chlorpheniramine: Telithromycin may reduce clearance of Chlorpheniramine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Chlorpheniramine if Telithromycin is initiated, discontinued or dose changed.

Ciclesonide: Telithromycin may reduce clearance of Ciclesonide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ciclesonide if Telithromycin is initiated, discontinued or dose changed.

Cilostazol: Telithromycin may reduce clearance of Cilostazol. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Cilostazol if Telithromycin is initiated, discontinued or dose changed.

Cinacalcet: Telithromycin may reduce clearance of Cinacalcet. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Cinacalcet if Telithromycin is initiated, discontinued or dose changed.

Cisapride: Telithromycin may reduce clearance of Cisapride. Concomitant therapy is contraindicated.

Citalopram: Telithromycin may reduce clearance of Citalopram. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Citalopram if Telithromycin is initiated, discontinued or dose changed.

Clarithromycin: Co-administration may result in altered plasma concentrations of Clarithromycin and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Clobazam: Telithromycin may reduce clearance of Clobazam. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Clobazam if Telithromycin is initiated, discontinued or dose changed.

Clonazepam: Telithromycin may reduce clearance of Clonazepam. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Clonazepam if Telithromycin is initiated, discontinued or dose changed.

Clorazepate: Telithromycin may reduce clearance of Clorazepate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Clorazepate if Telithromycin is initiated, discontinued or dose changed.

Cocaine: Telithromycin may reduce clearance of Cocaine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Cocaine if Telithromycin is initiated, discontinued or dose changed.

Colchicine: Telithromycin may reduce clearance of Colchicine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Colchicine if Telithromycin is initiated, discontinued or dose changed.

Conivaptan: Co-administration may result in altered plasma concentrations of Conivaptan and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Cyclosporine: Telithromycin may reduce clearance of cyclosporine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of cyclosporine if telithromycin is initiated, discontinued or dose changed.

Dantrolene: Telithromycin may increase the serum concentration of dantrolene by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of dantrolene if telithromycin is initiated, discontinued or dose changed.

Dapsone: Telithromycin may reduce clearance of Dapsone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Dapsone if Telithromycin is initiated, discontinued or dose changed.

Darifenacin: Telithromycin may reduce clearance of Darifenacin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Darifenacin if Telithromycin is initiated, discontinued or dose changed.

Darunavir: Co-administration may result in altered plasma concentrations of Darunavir and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Dasatinib: Telithromycin may reduce clearance of Dasatinib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Dasatinib if Telithromycin is initiated, discontinued or dose changed.

Delavirdine: Delavirdine may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Dexamethasone: Co-administration may cause decreased Telithromycin and increased Dexamethasone plasma concentrations. Consider alternate therapy.

Diazepam: Telithromycin may reduce clearance of Diazepam. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Diazepam if Telithromycin is initiated, discontinued or dose changed.

Dicumarol: Telithromycin may increase the anticoagulant effect of dicumarol.

Digitoxin: Telithromycin may reduce clearance of Digitoxin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Digitoxin if Telithromycin is initiated, discontinued or dose changed.

Digoxin: Telithromycin may increase the plasma concentration of Digoxin. Monitor for changes in Digoxin efficacy/toxicity if Telithromycin is initiated, discontinued or dose changed.

Dihydroergotamine: Telithromycin may reduce clearance of Dihydroergotamine. Concomitant therapy is contraindicated.

Diltiazem: Telithromycin may reduce clearance of Diltiazem. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Diltiazem if Telithromycin is initiated, discontinued or dose changed.

Disopyramide: Telithromycin may reduce clearance of Disopyramide. Concomitant therapy should be avoided.

Docetaxel: Telithromycin may reduce clearance of Docetaxel. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Docetaxel if Telithromycin is initiated, discontinued or dose changed.

Dofetilide: Increased risk of cardiotoxicity and arrhythmias

Doxepin: Telithromycin may reduce clearance of Doxepin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Doxepin if Telithromycin is initiated, discontinued or dose changed.

Doxorubicin: Telithromycin may reduce clearance of Doxorubicin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Doxorubicin if Telithromycin is initiated, discontinued or dose changed.

Efavirenz: Efavirenz may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Eletriptan: Telithromycin may reduce clearance of Eletriptan. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Eletriptan if Telithromycin is initiated, discontinued or dose changed.

Eplerenone: Telithromycin may reduce clearance of Eplerenone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Eplerenone if Telithromycin is initiated, discontinued or dose changed.

Ergoloid mesylate: Telithromycin may reduce clearance of Ergoloid mesylates. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ergoloid mesylates if Telithromycin is initiated, discontinued or dose changed.

Ergonovine: Telithromycin may reduce clearance of Ergonovine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ergonivine if Telithromycin is initiated, discontinued or dose changed.

Ergotamine: Telithromycin may reduce clearance of Ergotamine. Concomitant therapy is contraindicated.

Erlotinib: Telithromycin may reduce clearance of Erlotinib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Erlotinib if Telithromycin is initiated, discontinued or dose changed.

Erythromycin: Telithromycin may reduce clearance of Erythromycin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Erythromycin if Telithromycin is initiated, discontinued or dose changed.

Escitalopram: Telithromycin may reduce clearance of Escitalopram. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Escitalopram if Telithromycin is initiated, discontinued or dose changed.

Eszopiclone: Telithromycin may reduce clearance of Eszopiclone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Eszopiclone if Telithromycin is initiated, discontinued or dose changed.

Ethosuximide: Telithromycin may reduce clearance of Ethosuximide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ethosuximide if Telithromycin is initiated, discontinued or dose changed.

Etoposide: Telithromycin may reduce clearance of Etoposide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Etoposide if Telithromycin is initiated, discontinued or dose changed.

Felbamate: Telithromycin may reduce clearance of Felbamate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Felbamate if Telithromycin is initiated, discontinued or dose changed.

Felodipine: Telithromycin may reduce clearance of Felodipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Felodipine if Telithromycin is initiated, discontinued or dose changed.

Fentanyl: Telithromycin may reduce clearance of Fentanyl. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Fentanyl if Telithromycin is initiated, discontinued or dose changed.

Flunisolide: Telithromycin may reduce clearance of Flunisolide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Flunisolide if Telithromycin is initiated, discontinued or dose changed.

Flurazepam: Telithromycin may reduce clearance of Flurazepam. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Flurazepam if Telithromycin is initiated, discontinued or dose changed.

Flutamide: Telithromycin may reduce clearance of Flutamide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Flutamide if Telithromycin is initiated, discontinued or dose changed.

Fluticasone Propionate: Telithromycin may reduce clearance of Fluticasone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Fluticasone if Telithromycin is initiated, discontinued or dose changed.

Fosamprenavir: Fosamprevavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Fosphenytoin: Fosphenytoin may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Gefitinib: Telithromycin may reduce clearance of Gefitinib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Gefitinib if Telithromycin is initiated, discontinued or dose changed.

Halofantrine: Telithromycin may reduce clearance of Halofantrine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Halofantrine if Telithromycin is initiated, discontinued or dose changed.

Haloperidol: Telithromycin may reduce clearance of Haloperidol. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Haloperidol if Telithromycin is initiated, discontinued or dose changed.

Ifosfamide: Telithromycin may reduce clearance of Ifosfamide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ifosfamide if Telithromycin is initiated, discontinued or dose changed.

Imatinib: Co-administration may result in altered plasma concentrations of Imatinib and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Indinavir: Indinavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Irinotecan: Telithromycin may reduce clearance of Irinotecan. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Irinotecan if Telithromycin is initiated, discontinued or dose changed.

Isoniazid: Isoniazid may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Isosorbide Dinitrate: Telithromycin may reduce clearance of Isosorbide Dinitrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Isosorbide Dinitrate if Telithromycin is initiated, discontinued or dose changed.

Isosorbide Mononitrate: Telithromycin may reduce clearance of Isosorbide Mononitrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Isosorbide Mononitrate if Telithromycin is initiated, discontinued or dose changed.

Isradipine: Telithromycin may reduce clearance of Isradipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Isradipine if Telithromycin is initiated, discontinued or dose changed.

Itraconazole: Itraconazole may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Ixabepilone: Telithromycin may reduce clearance of Ixabepilone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ixabepilone if Telithromycin is initiated, discontinued or dose changed.

Ketamine: Telithromycin may reduce clearance of Ketamine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Ketamine if Telithromycin is initiated, discontinued or dose changed.

Ketoconazole: Ketoconazole may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Lapatinib: Telithromycin may reduce clearance of Lapatinib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Lapatinib if Telithromycin is initiated, discontinued or dose changed.

Lidocaine: Telithromycin may reduce clearance of Lidocaine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Lidocaine if Telithromycin is initiated, discontinued or dose changed.

Lopinavir: Lopinavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Lovastatin: Telithromycin may increase the adverse effects of lovastatin by decreasing its metabolism. Concomitant therapy should be avoided.

Lumefantrine: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Maraviroc: Telithromycin may reduce clearance of Maraviroc. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Maraviroc if Telithromycin is initiated, discontinued or dose changed.

Mefloquine: Telithromycin may reduce clearance of Mefloquine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Mefloquine if Telithromycin is initiated, discontinued or dose changed.

Methadone: Telithromycin may reduce clearance of Methadone. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Methadone if Telithromycin is initiated, discontinued or dose changed.

Methylergonovine: Telithromycin may reduce clearance of Methylergonovine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Methylergonovine if Telithromycin is initiated, discontinued or dose changed.

Methysergide: Risk of ergotism and severe ischemia with this association

Metoprolol: Telithromycin may possibly increase metoprolol effect

Miconazole: Miconazole may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Midazolam: Telithromycin may increase the effect and toxicity of the benzodiazepine, midazolam.

Mirtazapine: Telithromycin may reduce clearance of Mirtazapine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Mirtazapine if Telithromycin is initiated, discontinued or dose changed.

Modafinil: Telithromycin may reduce clearance of Modafinil. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Modafinil if Telithromycin is initiated, discontinued or dose changed.

Moricizine: Telithromycin may reduce clearance of Moricizine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Moricizine if Telithromycin is initiated, discontinued or dose changed.

Nafcillin: Nafcillin may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Nateglinide: Telithromycin may reduce clearance of Nateglenide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nateglenide if Telithromycin is initiated, discontinued or dose changed.

Nefazodone: Co-administration may result in altered plasma concentrations of Nefazodone and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Nelfinavir: Nelfinavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Nevirapine: Nevirapine may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Nicardipine: Co-administration may result in altered plasma concentrations of Nicardipine and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Nifedipine: Telithromycin may reduce clearance of Nifedipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nifedipine if Telithromycin is initiated, discontinued or dose changed.

Nilotinib: Telithromycin may reduce clearance of Nilotinib. Concomitant therapy should be avoided.

Nimodipine: Telithromycin may reduce clearance of Nimodipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nimodipine if Telithromycin is initiated, discontinued or dose changed.

Nisoldipine: Telithromycin may reduce clearance of Nisoldipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nisoldipine if Telithromycin is initiated, discontinued or dose changed.

Nitrendipine: Telithromycin may reduce clearance of Nitrendipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nitrendipine if Telithromycin is initiated, discontinued or dose changed.

Oxcarbazepine: Oxcarbazepine may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Paclitaxel: Telithromycin may reduce clearance of Paclitaxel. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Paclitaxel if Telithromycin is initiated, discontinued or dose changed.

Pentobarbital: Pentobarbital may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Pergolide: Telithromycin may reduce clearance of Pergolide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Pergolide if Telithromycin is initiated, discontinued or dose changed.

Phencyclidine: Telithromycin may reduce clearance of Phencyclidine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Phencyclidine if Telithromycin is initiated, discontinued or dose changed.

Phenobarbital: Phenobarbital may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Phenytoin: Phenytoin may decrease the plasma concentration of Telithromycin by increasing its metabolism. Consider alternate therapy.

Pimozide: Telithromycin may reduce clearance of Pimozide. Concomitant therapy is contraindicated.

Pipotiazine: Telithromycin may reduce clearance of Pipotiazine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Pipotiazine if Telithromycin is initiated, discontinued or dose changed.

Posaconazole: Posaconazole may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Praziquantel: Telithromycin may reduce clearance of Praziquantel. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Praziquantel if Telithromycin is initiated, discontinued or dose changed.

Primidone: Primidone may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Quetiapine: Telithromycin may reduce clearance of Quetiapine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Quetiapine if Telithromycin is initiated, discontinued or dose changed.

Quinidine: Co-administration may result in altered plasma concentrations of Quinidine and/or Telithromycin. Consider alternate therapy or monitor for changes in the the therapeutic/adverse effects of both agents during concomitant therapy.

Quinidine barbiturate: Increased risk of cardiotoxicity and arrhythmias

Quinine: Telithromycin may reduce clearance of Quinine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Quinine if Telithromycin is initiated, discontinued or dose changed.

Ranolazine: Telithromycin may reduce clearance of Ranolazine. Concomitant therapy should be avoided.

Repaglinide: Telithromycin may reduce clearance of Repaglinide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Repaglinide if Telithromycin is initiated, discontinued or dose changed.

Rifabutin: Rifabutin may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Rifampin: Rifampin may decrease the plasma concentration of Telithromycin. Concomitant therapy should be avoided.

Rifapentine: Rifapentine may decrease the plasma concentration of Telithromycin. Consider alternate therapy.

Ritonavir: Ritonavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Rivaroxaban: Telithromycin may reduce clearance of Rivaroxaban. Concomitant therapy is contraindicated.

Salmeterol: Telithromycin may reduce clearance of Salmeterol. Concomitant therapy is contraindicated.

Saquinavir: Saquinavir may increase the plasma concentration of Telithromycin. Consider alternate therapy or monitor therapeutic/adverse effects.

Sibutramine: Telithromycin may reduce clearance of Sibutramine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Sibutramine if Telithromycin is initiated, discontinued or dose changed.

Sildenafil: Telithromycin may reduce clearance of Sildenafil. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Sildenafil if Telithromycin is initiated, discontinued or dose changed.

Simvastatin: Telithromycin may increase the adverse effects of simvastatin by decreasing its metabolism. Concomitant therapy should be avoided.

Sirolimus: Telithromycin may reduce clearance of Sirolimus. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Sirolimus if Telithromycin is initiated, discontinued or dose changed.

Solifenacin: Telithromycin may reduce clearance of Solifenacin. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Solifenacin if Telithromycin is initiated, discontinued or dose changed.

Sotalol: Additive QTc-prolongation may occur increasing the risk of serious ventricular arrhythmias. Concomitant therapy should be used with caution.

Sufentanil: Telithromycin may reduce clearance of Sufentanil. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Sufentanil if Telithromycin is initiated, discontinued or dose changed.

Sunitinib: Telithromycin may reduce clearance of Sunitinib. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Sunitinib if Telithromycin is initiated, discontinued or dose changed.

Tacrolimus: Additive QTc-prolongation may occur increasing the risk of serious ventricular arrhythmias. Concomitant therapy should be used with caution. Telithromycin, a strong CYP3A4 inhibitor, may also increase the serum concentration of Tacrolimus by inhibiting its metabolism and clearance.

Tadalafil: Telithromycin may reduce the metabolism of Tadalafil. Concomitant therapy should be avoided if possible due to high risk of Tadalafil toxicity.

Tamoxifen: Telithromycin may reduce clearance of Tamoxifen. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Tamoxifen if Telithromycin is initiated, discontinued or dose changed.

Tamsulosin: Telithromycin, a CYP3A4 inhibitor, may decrease the metabolism and clearance of Tamsulosin, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in therapeutic/adverse effects of Tamsulosin if Telithromycin is initiated, discontinued, or dose changed.

Temsirolimus: Telithromycin may inhibit the metabolism and clearance of Temsirolimus. Concomitant therapy should be avoided.

Teniposide: The strong CYP3A4 inhibitor, Telithromycin, may decrease the metabolism and clearance of Teniposide, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Teniposide if Telithromycin is initiated, discontinued or dose changed.

Terfenadine: Increased risk of cardiotoxicity and arrhythmias

Tetrabenazine: Telithromycin may increase the QTc-prolonging effect of Tetrabenazine. Concomitant therapy should be avoided.

Theophylline: Telithromycin may reduce clearance of Theophylline. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Theophylline if Telithromycin is initiated, discontinued or dose changed.

Thioridazine: Telithromycin may increase the QTc-prolonging effect of Thioridazine. Concomitant therapy should be avoided.

Thiothixene: May cause additive QTc-prolonging effects. Increased risk of ventricular arrhythmias. Consider alternate therapy. Thorough risk:benefit assessment is required prior to co-administration.

Tiagabine: The strong CYP3A4 inhibitor, Telithromycin, may decrease the metabolism and clearance of Tiagabine, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Tiagabine if Telithromycin is initiated, discontinued or dose changed.

Tolterodine: Telithromycin may decrease the metabolism and clearance of Tolterodine. Adjust Tolterodine dose and monitor for efficacy and toxicity.

Toremifene: Additive QTc-prolongation may occur, increasing the risk of serious ventricular arrhythmias. Consider alternate therapy. A thorough risk:benefit assessment is required prior to co-administration.

Tramadol: Telithromycin may decrease the metabolism and clearance of tramadol. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of tramadol if telithromycin is initiated, discontinued or dose changed.

Trazodone: The CYP3A4 inhibitor, Telithromycin, may increase Trazodone efficacy/toxicity by decreasing Trazodone metabolism and clearance. Consider alternate therapy or monitor for changes in Trazodone efficacy/toxicity if Telithromycin is initiated, discontinued or dose changed.

Triazolam: Telithromycin may increase the effect and toxicity of the benzodiazepine, triazolam.

Trimipramine: Additive QTc-prolongation may occur, increasing the risk of serious ventricular arrhythmias. Telithromycin, a strong CYP3A4 inhibitor, may also decrease the metabolism and clearance of Trimipramine, a CYP3A4 substrate. Concomitant therapy should be used with caution.

Valproic Acid: The macrolide antibiotic, Erythromycin, may increase the serum concentratin of Valproic acid. Consider alternate therapy or monitor for changes in Valproic acid therapeutic and adverse effects if Telithromycin is initiated, discontinued or dose changed.

Vardenafil: Telithromycin, a strong CYP3A4 inhibitor, may reduce the metabolism and clearance of Vardenafil. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of Vardenafil.

Venlafaxine: Telithromycin, a CYP3A4 inhibitor, may decrease the metabolism and clearance of Venlafaxine, a CYP3A4 substrate. Monitor for changes in therapeutic/adverse effects of Venlafaxine if Telithromycin is initiated, discontinued, or dose changed.

Verapamil: Telithromycin, a CYP3A4 and p-glycoprotein inhibitor, may increase the Vinblastine serum concentration and distribution in certain cells. Consider alternate therapy to avoid Vinblastine toxicity. Monitor for changes in the therapeutic/adverse effects of Vinblastine if Telithromycin is initiated, discontinued or dose changed.

Vinblastine: Telithromycin, a CYP3A4 and p-glycoprotein inhibitor, may increase the Vinblastine serum concentration and distribution in certain cells. Consider alternate therapy to avoid Vinblastine toxicity. Monitor for changes in the therapeutic and adverse effects of Vinblastine if Telithromycin is initiated, discontinued or dose changed.

Vincristine: Telithromycin, a CYP3A4 and p-glycoprotein inhibitor, may increase the Vincristine serum concentration and distribution in certain cells. Consider alternate therapy to avoid Vincristine toxicity. Monitor for changes in the therapeutic and adverse effects of Vincristine if Telithromycin is initiated, discontinued or dose changed.

Vinorelbine: Telithromycin, a CYP3A4 and p-glycoprotein inhibitor, may increase the Vinorelbine serum concentration and distribution in certain cells. Consider alternate therapy to avoid Vinorelbine toxicity. Monitor for changes in the therapeutic and adverse effects of Vinorelbine if Telithromycin is initiated, discontinued or dose changed.

Voriconazole: Voriconazole, a strong CYP3A4 inhibitor, may increase the serum concentration of telithromycin by decreasing its metabolism. Telithromycin may increase the serum concentration of voriconazole by decreasing its metabolism. Monitor for changes in the therapeutic and adverse effects of both agents if concomitant therapy is initiated, discontinued or dose changed. QTc interval prolongation may also occur.

Vorinostat: Additive QTc prolongation may occur. Consider alternate therapy or monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).

Warfarin: Telithromycin may increase the anticoagulant effect of Warfarin. INR should be monitored and Warfarin dose adjusted accordingly during concomitant therapy.

Ziprasidone: Additive QTc-prolonging effects may increase the risk of severe arrhythmias. Concomitant therapy should be avoided.

Zolpidem: Telithromycin, a strong CYP3A4 inhibitor, may increase the serum concentration of zolpidem by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zolpidem if telithromycin is initiated, discontinued or dose changed.

Zonisamide: Telithromycin, a strong CYP3A4 inhibitor, may increase the serum concentration of zonisamide by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zonisamide if telithromycin is initiated, discontinued or dose changed.

Zopiclone: Telithromycin, a strong CYP3A4 inhibitor, may increase the serum concentration of zopiclone by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zopiclone if telithromycin is initiated, discontinued or dose changed.

Zuclopenthixol: Additive QTc prolongation may occur. Consider alternate therapy or use caution and monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).