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|Ketek tablets |
| Drugs search, click the first letter of a drug name: | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 1 | 2 | 3 | 4 | 5 | 6 | 8 | 9 Home KetekGeneric Name: telithromycin Dosage Form: Tablets To reduce the development of drug-resistant bacteria and maintain the effectiveness of Ketek and other antibacterial drugs, Ketek should be used only to treat infections that are proven or strongly suspected to be caused by bacteria. Ketek DescriptionKetek® 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 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. Ketek - Clinical PharmacologyPharmacokineticsAbsorptionFollowing oral administration, telithromycin reached maximal concentration at about 1 hour (0.5 – 4 hours). It has an absolute bioavailability of 57% in both young and elderly subjects. The rate and extent of absorption are unaffected by food intake, thus Ketek tablets can be given without regard to food. In healthy adult subjects, peak plasma telithromycin concentrations of approximately 2 µg/mL are attained at a median of 1 hour after an 800-mg oral dose. Steady-state plasma concentrations are reached within 2 to 3 days of once daily dosing with telithromycin 800 mg. Following oral dosing, the mean terminal elimination half-life of telithromycin is 10 hours. The pharmacokinetics of telithromycin after administration of single and multiple (7 days) once daily 800-mg doses to healthy adult subjects are shown in Table 1.
In a patient population, mean peak and trough plasma concentrations were 2.9 µg/mL (±1.55), (n=219) and 0.2 µg/mL (±0.22), (n=204), respectively, after 3 to 5 days of Ketek 800 mg once daily. DistributionTotal in vitro protein binding is approximately 60% to 70% and is primarily due to human serum albumin. Protein binding is not modified in elderly subjects and in patients with hepatic impairment. The volume of distribution of telithromycin after intravenous infusion is 2.9 L/kg. Telithromycin concentrations in bronchial mucosa, epithelial lining fluid, and alveolar macrophages after 800 mg once daily dosing for 5 days in patients are displayed in Table 2.
Telithromycin concentration in white blood cells exceeds the concentration in plasma and is eliminated more slowly from white blood cells than from plasma. Mean white blood cell concentrations of telithromycin peaked at 72.1µg/mL at 6 hours, and remained at 14.1 µg/mL 24 hours after 5 days of repeated dosing of 600 mg once daily. After 10 days, repeated dosing of 600 mg once daily, white blood cell concentrations remained at 8.9 µg/mL 48 hours after the last dose. MetabolismIn total, metabolism accounts for approximately 70% of the dose. In plasma, the main circulating compound after administration of an 800-mg radiolabeled dose was parent compound, representing 56.7% of the total radioactivity. The main metabolite represented 12.6% of the AUC of telithromycin. Three other plasma metabolites were quantified, each representing 3% or less of the AUC of telithromycin. It is estimated that approximately 50% of its metabolism is mediated by CYP 450 3A4 and the remaining 50% is CYP 450-independent. EliminationThe 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. Special populationsGenderThere was no significant difference between males and females in mean AUC, Cmax, and elimination half-life in two studies; one in 18 healthy young volunteers (18 to 40 years of age) and the other in 14 healthy elderly volunteers (65 to 92 years of age), given single and multiple once daily doses of 800 mg of Ketek. Hepatic insufficiencyIn a single-dose study (800 mg) in 12 patients and a multiple-dose study (800 mg) in 13 patients with mild to severe hepatic insufficiency (Child Pugh Class A, B and C), the Cmax, AUC and t1/2 of telithromycin were similar to those obtained in age- and sex-matched healthy subjects. In both studies, an increase in renal elimination was observed in hepatically impaired patients indicating that this pathway may compensate for some of the decrease in metabolic clearance. No dosage adjustment is recommended due to hepatic impairment. (See PRECAUTIONS, General and DOSAGE AND ADMINISTRATION.) Renal insufficiencyIn a multiple-dose study, 36 subjects with varying degrees of renal impairment received 400 mg, 600 mg, or 800 mg Ketek once daily for 5 days. There was a 1.4-fold increase in Cmax,ss, and a 1.9-fold increase in AUC (0–24)ss at 800 mg multiple doses in the severely renally impaired group (CLCR< 30 mL/min) compared to healthy volunteers. Renal excretion may serve as a compensatory elimination pathway for telithromycin in situations where metabolic clearance is impaired. Patients with severe renal impairment are prone to conditions that may impair their metabolic clearance. Therefore, in the presence of severe renal impairment (CLCR< 30 mL/min), a reduced dosage of Ketek is recommended. (See DOSAGE AND ADMINISTRATION.) In a single-dose study in patients with end-stage renal failure on hemodialysis (n=10), the mean Cmax and AUC values were similar to normal healthy subjects when Ketek was administered 2 hours post-dialysis. However, the effect of dialysis on removing telithromycin from the body has not been studied. Multiple insufficiencyThe effects of co-administration of ketoconazole in 12 subjects (age ≥ 60 years), with impaired renal function were studied (CLCR= 24 to 80 mL/min). In this study, when severe renal insufficiency(CLCR< 30 mL/min, n=2) and concomitant impairment of CYP 3A4 metabolism pathway were present, telithromycin exposure (AUC (0–24)) was increased by approximately 4- to 5-fold compared with the exposure in healthy subjects with normal renal function receiving telithromycin alone. In the presence of severe renal impairment (CLCR< 30 mL/min), with coexisting hepatic impairment, a reduced dosage of Ketek is recommended. (See PRECAUTIONS, General and DOSAGE AND ADMINISTRATION.) GeriatricPharmacokinetic data show that there is an increase of 1.4-fold in exposure (AUC) in 20 patients ≥ 65 years of age with community acquired pneumonia in a Phase III study, and a 2.0-fold increase in exposure (AUC) in 14 subjects ≥ 65 years of age as compared with subjects less than 65 years of age in a Phase I study. No dosage adjustment is required based on age alone. Drug-drug interactionsStudies were performed to evaluate the effect of CYP 3A4 inhibitors on telithromycin and the effect of telithromycin on drugs that are substrates of CYP 3A4 and CYP 2D6. In addition, drug interaction studies were conducted with several other concomitantly prescribed drugs. CYP 3A4 inhibitorsItraconazoleA multiple-dose interaction study with itraconazole showed that Cmax of telithromycin was increased by 22% and AUC by 54%. KetoconazoleA multiple-dose interaction study with ketoconazole showed that Cmax of telithromycin was increased by 51% and AUC by 95%. Grapefruit juiceWhen telithromycin was given with 240 mL of grapefruit juice after an overnight fast to healthy subjects, the pharmacokinetics of telithromycin were not affected. CYP 3A4 substratesCisaprideSteady-state peak plasma concentrations of cisapride (an agent with the potential to increase QT interval) were increased by 95% when co-administered with repeated doses of telithromycin, resulting in significant increases in QTc. (See CONTRAINDICATIONS.) SimvastatinWhen simvastatin was co-administered with telithromycin, there was a 5.3-fold increase in simvastatin Cmax, an 8.9-fold increase in simvastatin AUC, a 15-fold increase in the simvastatin active metabolite Cmax, and a 12-fold increase in the simvastatin active metabolite AUC. (See PRECAUTIONS.) In another study, when simvastatin and telithromycin were administered 12 hours apart, there was a 3.4-fold increase in simvastatin Cmax, a 4.0-fold increase in simvastatin AUC, a 3.2-fold increase in the active metabolite Cmax, and a 4.3-fold increase in the active metabolite AUC. (See PRECAUTIONS.) MidazolamConcomitant administration of telithromycin with intravenous or oral midazolam resulted in 2- and 6-fold increases, respectively, in the AUC of midazolam due to inhibition of CYP 3A4-dependent metabolism of midazolam. (See PRECAUTIONS.) CYP 2D6 substratesParoxetineThere was no pharmacokinetic effect on paroxetine when telithromycin was co-administered. MetoprololWhen metoprolol was co-administered with telithromycin, there was an increase of approximately 38% on the Cmax and AUC of metoprolol, however, there was no effect on the elimination half-life of metoprolol. Telithromycin exposure is not modified with concomitant single-dose administration of metoprolol. (See PRECAUTIONS, Drug interactions.) Other drug interactionsDigoxinThe plasma peak and trough levels of digoxin were increased by 73% and 21%, respectively, in healthy volunteers when co-administered with telithromycin. However, trough plasma concentrations of digoxin (when equilibrium between plasma and tissue concentrations has been achieved) ranged from 0.74 to 2.17 ng/mL. There were no significant changes in ECG parameters and no signs of digoxin toxicity. (See PRECAUTIONS.) TheophyllineWhen theophylline was co-administered with repeated doses of telithromycin, there was an increase of approximately 16% and 17% on the steady-state Cmax and AUC of theophylline. Co-administration of theophylline may worsen gastrointestinal side effects such as nausea and vomiting, especially in female patients. It is recommended that telithromycin should be taken with theophylline 1 hour apart to decrease the likelihood of gastrointestinal side effects. SotalolTelithromycin has been shown to decrease the Cmax and AUC of sotalol by 34% and 20%, respectively, due to decreased absorption. WarfarinWhen co-administered with telithromycin in healthy subjects, there were no pharmacodynamic or pharmacokinetic effects on racemic warfarin. Oral contraceptivesWhen oral contraceptives containing ethinyl estradiol and levonorgestrel were co-administered with telithromycin, the steady-state AUC of ethinyl estradiol did not change and the steady-state AUC of levonorgestrel was increased by 50%. The pharmacokinetic/pharmacodynamic study showed that telithromycin did not interfere with the antiovulatory effect of oral contraceptives containing ethinyl estradiol and levonorgestrel. Ranitidine, antacidThere was no clinically relevant pharmacokinetic interaction of ranitidine or antacids containing aluminum and magnesium hydroxide on telithromycin. RifampinDuring concomitant administration of rifampin and Ketek in repeated doses, Cmax and AUC of telithromycin were decreased by 79%, and 86%, respectively. (See PRECAUTIONS, Drug Interactions.) MicrobiologyTelithromycin belongs to the ketolide class of antibacterials and is structurally related to the macrolide family of antibiotics. Telithromycin concentrates in phagocytes where it exhibits activity against intracellular respiratory pathogens. In vitro, telithromycin has been shown to demonstrate concentration-dependent bactericidal activity against isolates of Streptococcus pneumoniae (including multi-drug resistant isolates [MDRSP*]). *MDRSP=Multi-drug resistant Streptococcus pneumoniae includes isolates known as PRSP (penicillin-resistant Streptococcus pneumoniae), and are isolates resistant to two or more of the following antimicrobials: penicillin, 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole. Mechanism of actionTelithromycin blocks protein synthesis 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 domain V binding site of telithromycin. Telithromycin may also inhibit the assembly of nascent ribosomal units. Mechanism of resistanceStaphylococcus aureus and Streptococcus pyogenes with the constitutive macrolide-lincosamide-streptogramin B (cMLSB) phenotype are resistant to telithromycin. Mutants of Streptococcus pneumoniae derived in the laboratory by serial passage in subinhibitory concentrations of telithromycin have demonstrated resistance based on L22 riboprotein mutations (telithromycin MICs are elevated but still within the susceptible range), one of two reported mutations affecting the L4 riboprotein, and production of K-peptide. The clinical significance of these laboratory mutants is not known. Cross resistanceTelithromycin does not induce resistance through methylase gene expression in erythromycin-inducibly resistant bacteria, a function of its 3-keto moiety. Telithromycin has not been shown to induce resistance to itself. List of MicroorganismsTelithromycin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical settings as described in the INDICATIONS AND USAGE section. Aerobic gram-positive microorganisms
*MDRSP=Multi-drug resistant Streptococcus pneumoniae includes isolates known as PRSP (penicillin-resistant S. pneumoniae), and are isolates resistant to two or more of the following antimicrobials: penicillin, 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole. Aerobic gram-negative microorganisms
Other microorganisms
The following in vitro data are available, but their clinical significance is unknown. At least 90% of the following microorganisms exhibit in vitro minimum inhibitory concentrations (MICs) less than or equal to the susceptible breakpoint for telithromycin. However, the safety and efficacy of telithromycin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials. Aerobic gram-positive microorganisms
Anaerobic bacteria
Other microorganisms
When available, the clinical microbiology laboratory should provide cumulative results of in vitro susceptibility test results for antimicrobial drugs used in local hospitals and practice areas to the physician as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. These reports should aid the physician in selecting the most effective antimicrobial. Dilution techniquesQuantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antibacterial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on dilution methods (broth or agar dilution)1,3 or equivalent with standardized inoculum and concentrations of telithromycin powder. The MIC values should be interpreted according to criteria provided in Table 3. Diffusion techniquesQuantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antibiotics. One such standardized procedure2,3 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 15 µg telithromycin to test the susceptibility of microorganisms to telithromycin. Disc diffusion zone sizes should be interpreted according to criteria in Table 3.
A report of "Susceptible" indicates that the antimicrobial is likely to inhibit growth of the pathogen if the antibacterial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone that prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the antimicrobial is not likely to inhibit growth of the pathogen if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected. Quality controlStandardized susceptibility test procedures require the use of quality control microorganisms to determine the performance of the test procedures1,2,3. Standard telithromycin powder should provide the MIC ranges for the quality control organisms in Table 4. For the disk diffusion technique, the 15-µg telithromycin disk should provide the zone diameter ranges for the quality control organisms in Table 4.
INDICATIONS AND USAGEKetek tablets are indicated for the treatment of infections caused by susceptible strains of the designated microorganisms in the conditions listed below for patients 18 years old and above. Acute bacterial exacerbation of chronic bronchitis due to Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis. Acute bacterial sinusitis due to Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, or Staphylococcus aureus. Community-acquired pneumonia (of mild to moderate severity) due to Streptococcus pneumoniae, (including multi-drug resistant isolates [MDRSP*]), Haemophilus influenzae, Moraxella catarrhalis, Chlamydophila pneumoniae, or Mycoplasma pneumoniae. *MDRSP, Multi-drug resistant Streptococcus pneumoniae includes isolates known as PRSP (penicillin-resistant Streptococcus pneumoniae), and are isolates resistant to two or more of the following antibiotics: penicillin, 2nd generation cephalosporins, e.g., cefuroxime, macrolides, tetracyclines and trimethoprim/sulfamethoxazole. To reduce the development of drug-resistant bacteria and maintain the effectiveness of Ketek and other antibacterial drugs, Ketek should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy. ContraindicationsKetek is contraindicated in patients with a history of hypersensitivity to telithromycin and/or any components of Ketek tablets, or any macrolide antibiotic. Ketek is contraindicated in patients with previous history of hepatitis and/or jaundice associated with the use of Ketek tablets, or any macrolide antibiotic. Concomitant administration of Ketek with cisapride or pimozide is contraindicated. (See CLINICAL PHARMACOLOGY, Drug-drug Interactions and PRECAUTIONS.) WarningsHepatotoxicityAcute hepatic failure and severe liver injury, in some cases fatal, have been reported in patients treated with Ketek. These hepatic reactions included fulminant hepatitis and hepatic necrosis leading to liver transplant, and were observed during or immediately after treatment. In some of these cases, liver injury progressed rapidly and occurred after administration of a few doses of Ketek. (See ADVERSE REACTIONS.) Physicians and patients should monitor for the appearance of signs or symptoms of hepatitis, such as fatigue, malaise, anorexia, nausea, jaundice, bilirubinuria, acholic stools, liver tenderness or hepatomegaly. Patients with signs or symptoms of hepatitis mustbe advised to discontinue Ketek and immediately seek medical evaluation, which should include liver function tests. (See ADVERSE REACTIONS, PRECAUTIONS, Information to Patients.) If clinical hepatitis or transaminase elevations combined with other systemic symptoms occur, Ketek should be permanently discontinued. Ketek must not be re-administered to patients with a previous history of hepatitis and/or jaundice associated with the use of Ketek tablets, or any macrolide antibiotic. (See CONTRAINDICATIONS.) Exacerbations of myasthenia gravisTelithromycin should not be used in patients with myasthenia gravis unless no other therapeutic alternatives are available. Exacerbations of myasthenia gravis have been reported in patients with myasthenia gravis treated with telithromycin. This has sometimes occurred within a few hours after intake of the first dose of telithromycin. Reports have included death and life-threatening acute respiratory failure with a rapid onset in patients with myasthenia gravis treated for respiratory tract infections with telithromycin. If other therapeutic alternatives are not available, patients with myasthenia gravis taking telithromycin must be closely monitored. Patients must be advised that if they experience exacerbation of their symptoms, they should discontinue treatment of Ketek and immediately seek medical attention. Supportive measures should be instituted as medically necessary. QTc interval prolongationTelithromycin has the potential to prolong the QTc interval of the electrocardiogram in some patients. QTc prolongation may lead to an increased risk for ventricular arrhythmias, including torsades de pointes. Thus, telithromycin should be avoided in patients with congenital prolongation of the QTc interval, and in patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia, and in patients receiving Class IA (e.g., quinidine and procainamide) or Class III (e.g., dofetilide) antiarrhythmic agents. No cardiovascular morbidity or mortality attributable to QTc prolongation occurred with telithromycin treatment in 4780 patients in clinical efficacy trials, including 204 patients having a prolonged QTc at baseline. Pseudomembranous colitisPseudomembranous colitis has been reported with nearly all antibacterial agents, including telithromycin, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of any antibacterial agents. Treatment with antibacterial agents alters the flora of the colon and may permit overgrowth of clostridia. Studies indicate that toxin-producing strains of Clostridium difficile are the primary cause of "antibiotic-associated colitis". After the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated. Mild cases of pseudomembranous colitis usually respond to drug discontinuation alone. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation, and treatment with an antibacterial drug clinically effective against C. difficile colitis. (See ADVERSE REACTIONS.) PrecautionsGeneralPrescribing Ketek in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria. Ketek may cause visual disturbances particularly in slowing the ability to accommodate and the ability to release accommodation. Visual disturbances included blurred vision, difficulty focusing, and diplopia. Most events were mild to moderate; however, severe cases have been reported. There have been post-marketing adverse event reports of syncope usually associated with vagal syndrome. Patients should be cautioned about the potential effects of these visual disturbances and syncope on driving a vehicle, operating machinery or engaging in other potentially hazardous activities. (See ADVERSE REACTIONS, CLINICAL STUDIES.) Hepatic dysfunction, including increased liver enzymes and hepatitis, with or without jaundice, has been reported with the use of Ketek. These events were generally reversible, though acute hepatic failure and severe liver injury, in some cases fatal, have been reported.(See WARNINGS, ADVERSE REACTIONS, Liver and biliary system.) Telithromycin is principally excreted via the liver and kidney. Telithromycin may be administered without dosage adjustment in the presence of hepatic impairment. In the presence of severe renal impairment (CLCR< 30 mL/min), a reduced dosage of Ketek is recommended. (See DOSAGE AND ADMINISTRATION.) Information for patientsThe following information and instructions should be communicated to the patient. Ketek may cause problems with vision particularly when looking quickly between objects close by and objects far away. These events include blurred vision, difficulty focusing, and objects looking doubled. Most events were mild to moderate; however, severe cases have been reported. Problems with vision were reported as having occurred after any dose during treatment, but most occurred following the first or second dose. These problems lasted several hours and in some patients came back with the next dose. (See PRECAUTIONS, General and ADVERSE REACTIONS.) If visual difficulties occur:
Patients should be aware of the possibility of experiencing syncope (fainting), and its impact on the ability to drive, especially if they are experiencing vagal symptoms (severe nausea, vomiting, and/or lightheadedness). If patients experience these symptoms, they should avoid driving a motor vehicle, operating heavy machinery, or engaging in otherwise hazardous activities. Patients should also be advised:
Drug interactionsTelithromycin is a strong inhibitor of the cytochrome P450 3A4 system. Co-administration of Ketek tablets and a drug primarily metabolized by the cytochrome P450 3A4 enzyme system may result in increased plasma concentration of the drug co-administered with telithromycin that could increase or prolong both the therapeutic and adverse effects. Therefore, appropriate dosage adjustments may be necessary for the drug co-administered with telithromycin. The use of Ketek is contraindicated with cisapride. (See CONTRAINDICATIONS and CLINICAL PHARMACOLOGY, Drug-drug interactions.) The use of Ketek is contraindicated with pimozide. Although there are no studies looking at the interaction between Ketek and pimozide, there is a potential risk of increased pimozide plasma levels by inhibition of CYP 3A4 pathways by Ketek as with macrolides. (See CONTRAINDICATIONS.) In a pharmacokinetic study, simvastatin levels were increased due to CYP 3A4 inhibition by telithromycin. (See CLINICAL PHARMACOLOGY, Other drug interactions.) Similarly, an interaction may occur with lovastatin or atorvastatin, but not with pravastatin or fluvastatin. High levels of HMG-CoA reductase inhibitors increase the risk of myopathy. Use of simvastatin, lovastatin, or atorvastatin concomitantly with Ketek should be avoided. If Ketek is prescribed, therapy with simvastatin, lovastatin, or atorvastatin should be suspended during the course of treatment. Monitoring of digoxin side effects or serum levels should be considered during concomitant administration of digoxin and Ketek. (See CLINICAL PHARMACOLOGY, Drug-drug interactions.) Patients should be monitored with concomitant administration of midazolam and dosage adjustment of midazolam should be considered if necessary. Precaution should be used with other benzodiazepines, which are metabolized by CYP 3A4 and undergo a high first-pass effect (e.g., triazolam). (See CLINICAL PHARMACOLOGY, Drug-drug interactions.) Concomitant treatment of Ketek with rifampin, a CYP 3A4 inducer, should be avoided. Concomitant administration of other CYP 3A4 inducers such as phenytoin, carbamazepine, or phenobarbital is likely to result in subtherapeutic levels of telithromycin and loss of effect. (See CLINICAL PHARMACOLOGY, Other drug interactions.) In patients treated with metoprolol for heart failure, the increased exposure to metoprolol, a CYP 2D6 substrate, may be of clinical importance. Therefore, co-administration of Ketek and metoprolol in patients with heart failure should be considered with caution. (See CLINICAL PHARMACOLOGY, Drug-drug interactions.) Spontaneous post-marketing reports suggest that administration of Ketek and oral anticoagulants concomitantly may potentiate the effectsof the oral anticoagulants. Consideration should be given to monitoring prothrombin times/INR while patients are receiving Ketek and oral anticoagulants simultaneously. No specific drug interaction studies have been performed to evaluate the following potential drug-drug interactions with Ketek. However, these drug interactions have been observed with macrolide products.
Laboratory test interactionsThere are no reported laboratory test interactions. Carcinogenesis, mutagenesis, impairment of fertilityLong-term studies in animals to determine the carcinogenic potential of Ketek have not been conducted. Telithromycin showed no evidence of genotoxicity in four tests: gene mutation in bacterial cells, gene mutation in mammalian cells, chromosome aberration in human lymphocytes, and the micronucleus test in the mouse. No evidence of impaired fertility in the rat was observed at doses estimated to be 0.61 times the human daily dose on a mg/m2 basis. At doses of 1.8–3.6 times the human daily dose, at which signs of parental toxicity were observed, moderate reductions in fertility indices were noted in male and female animals treated with telithromycin. PregnancyTeratogenic effectsPregnancy Category C. Telithromycin was not teratogenic in the rat or rabbit. Reproduction studies have been performed in rats and rabbits, with effect on pre-post natal development studied in the rat. At doses estimated to be 1.8 times (900 mg/m2) and 0.49 times (240 mg/m2) the daily human dose of 800 mg (492 mg/m2) in the rat and rabbit, respectively, no evidence of fetal terata was found. At doses higher than the 900 mg/m2 and 240 mg/m2 in rats and rabbits, respectively, maternal toxicity may have resulted in delayed fetal maturation. No adverse effects on prenatal and postnatal development of rat pups were observed at 1.5 times (750 mg/m2/d) the daily human dose. There are no adequate and well-controlled studies in pregnant women. Telithromycin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Nursing mothersTelithromycin is excreted in breast milk of rats. Telithromycin may also be excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Ketek is administered to a nursing mother. Pediatric useThe safety and effectiveness of Ketek in pediatric patients has not been established. Geriatric useIn all Phase III clinical trials (n=4,780), Ketek was administered to 694 patients who were 65 years and older, including 231 patients who were 75 years and older. Efficacy and safety in elderly patients ≥ 65 years were generally similar to that observed in younger patients; however, greater sensitivity of some older individuals cannot be ruled out. No dosage adjustment is required based on age alone. (See CLINICAL PHARMACOLOGY, Special populations, Geriatric and DOSAGE AND ADMINISTRATION.) Adverse ReactionsIn Phase III clinical trials, 4,780 patients (n=2702 in controlled trials) received daily oral doses of Ketek 800 mg once daily for 5 days or 7 to 10 days. Most adverse events were mild to moderate in severity. In the combined Phase III studies, discontinuation due to treatment-emergent adverse events occurred in 4.4% of Ketek-treated patients and 4.3% of combined comparator-treated patients. Most discontinuations in the Ketek group were due to treatment-emergent adverse events in the gastrointestinal body system, primarily diarrhea (0.9% for Ketek vs. 0.7% for comparators), nausea (0.7% for Ketek vs. 0.5% for comparators). All and possibly related treatment-emergent adverse events (TEAEs) occurring in controlled clinical studies in ≥ 2.0% of all patients are included below:
The following events judged by investigators to be at least possibly drug related were observed infrequently (≥ 0.2% and < 2%), in Ketek-treated patients in the controlled Phase III studies. Gastrointestinal system: abdominal distension, dyspepsia, gastrointestinal upset, flatulence, constipation, gastroenteritis, gastritis, anorexia, oral candidiasis, glossitis, stomatitis, watery stools. Liver and biliary system: abnormal liver function tests: increased transaminases, increased liver enzymes (e.g., ALT, AST) were usually asymptomatic and reversible. ALT elevations above 3 times the upper limit of normal were observed in 1.6%, and 1.7% of patients treated with Ketek and comparators, respectively. Hepatitis, with or without jaundice, occurred in 0.07% of patients treated with Ketek, and was reversible. (See PRECAUTIONS, General.) Nervous system: dry mouth, somnolence, insomnia, vertigo, increased sweating Body as a whole: abdominal pain, upper abdominal pain, fatigue Special senses: Visual adverse events most often included blurred vision, diplopia, or difficulty focusing. Most events were mild to moderate; however, severe cases have been reported. Some patients discontinued therapy due to these adverse events. Visual adverse events were reported as having occurred after any dose during treatment, but most visual adverse events (65%) occurred following the first or second dose. Visual events lasted several hours and recurred upon subsequent dosing in some patients. For patients who continued treatment, some resolved on therapy while others continued to have symptoms until they completed the full course of treatment. (See PRECAUTIONS, General and PRECAUTIONS, Information for patients.) Females and patients under 40 years old experienced a higher incidence of telithromycin-associated visual adverse events. (See CLINICAL STUDIES.) Urogenital system: vaginal candidiasis, vaginitis, vaginosis fungal Skin: rash Hematologic: increased platelet count Other possibly related clinically-relevant events occurring in <0.2% of patients treated with Ketek from the controlled Phase III studies included: anxiety, bradycardia, eczema, elevated blood bilirubin, erythema multiforme, flushing, hypotension, increased blood alkaline phosphatase, increased eosinophil count, paresthesia, pruritus, urticaria. Post-Marketing Adverse Event ReportsIn addition to adverse events reported from clinical trials, the following events have been reported from worldwide post-marketing experience with Ketek. Allergic: face edema, rare reports of severe allergic reactions, including angioedema and anaphylaxis. Cardiovascular: atrial arrhythmias, palpitations Gastrointestinal system: pancreatitis Liver and biliary system: Hepatic dysfunction has been reported. Severe and in some cases fatal hepatotoxicity, including fulminant hepatitis, hepatic necrosis and hepatic failure have been reported in patients treated with Ketek. These hepatic reactions were observed during or immediately after treatment. In some of these cases, liver injury progressed rapidly and occurred after administration of only a few doses of Ketek. (See CONTRAINDICATIONS and WARNINGS). Severe reactions, in some but not all cases, have been associated with serious underlying diseases or concomitant medications. Data from post-marketing reports and clinical trials show that most reported cases of hepatic dysfunction were mild to moderate. (See PRECAUTIONS, General.) Musculoskeletal: muscle cramps, rare reports of exacerbation of myasthenia gravis. (See WARNINGS.) Nervous system: syncope usually associated with vagal syndrome. OverdosageIn the event of acute overdosage, the stomach should be emptied by gastric lavage. The patient should be carefully monitored (e.g., ECG, electrolytes) and given symptomatic and supportive treatment. Adequate hydration should be maintained. The effectiveness of hemodialysis in an overdose situation with Ketek is unknown. Ketek Dosage and AdministrationThe dose of Ketek tablets is 800 mg taken orally once every 24 hours. The duration of therapy depends on the infection type and is described below. Ketek tablets can be administered with or without food.
Ketek may be administered without dosage adjustment in the presence of hepatic impairment. In the presence of severe renal impairment (CLCR< 30 mL/min), including patients who need dialysis, the dose should be reduced to Ketek 600 mg once daily. In patients undergoing hemodialysis, Ketek should be given after the dialysis session on dialysis days. (See CLINICAL PHARMACOLOGY, Renal insufficiency.) In the presence of severe renal impairment (CLCR< 30 mL/min), with coexisting hepatic impairment, the dose should be reduced to Ketek 400 mg once daily. (See CLINICAL PHARMACOLOGY, Multiple insufficiency.) How is Ketek SuppliedKetek® 400 mg tablets are supplied as light-orange, oval, film-coated tablets, imprinted "H3647" on one side and "400" on the other side. These are packaged in bottles and blister cards (Ketek Pak™ and unit dose) as follows: Bottles of 60 (NDC 0088-2225-41) Ketek Pak™, 10-tablet cards (2 tablets per blister cavity) (NDC 0088-2225-07) Unit dose package of 100 (blister pack) (NDC 0088-2225-49) Ketek® 300 mg tablets are supplied as light-orange, oval, film-coated tablets, imprinted "38AV" on one side and blank on the other side. These are packaged in bottles as follows: Bottles of 20 (NDC 0088-2223-20) Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F) [see USP Controlled Room Temperature]. Clinical StudiesCommunity-acquired pneumonia (CAP)Ketek was studied in four randomized, double-blind, controlled studies and four open-label studies for the treatment of community-acquired pneumonia. Patients with mild to moderate CAP who were considered appropriate for oral outpatient treatment were enrolled in these trials. Patients with severe pneumonia were excluded based on any one of the following: ICU admission, need for parenteral antibiotics, respiratory rate > 30/minute, hypotension, altered mental status, < 90% oxygen saturation by pulse oximetry, or white blood cell count < 4000/mm3. Total number of clinically evaluable patients in the telithromycin group included 2016 patients.
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