Rifapex

Active Pulmonary Tuberculosis

Rifapex® (rifapentine) is indicated in adults and children 12 years and older for the treatment of active pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis. Rifapex must always be used in combination with one or more antituberculosis (anti-TB) drugs to which the isolate is susceptible.

Limitations of Use

Do not use Rifapex monotherapy in either the initial or the continuation phases of active antituberculous treatment.

Rifapex should not be used once-weekly in the continuation phase regimen in combination with isoniazid (INH) in HIV-infected patients with active pulmonary tuberculosis because of a higher rate of failure and/or relapse with rifampin (RIF)-resistant organisms.

Rifapex has not been studied as part of the initial phase treatment regimen in HIV-infected patients with active pulmonary tuberculosis.

Latent Tuberculosis Infection

Rifapex is indicated in adults and children 2 years and older for the treatment of latent tuberculosis infection caused by Mycobacterium tuberculosis in patients at high risk of progression to tuberculosis disease (including those in close contact with active tuberculosis patients, recent conversion to a positive tuberculin skin test, HIV-infected patients, or those with pulmonary fibrosis on radiograph).

Limitations of Use

Active tuberculosis disease should be ruled out before initiating treatment for latent tuberculosis infection.

Rifapex must always be used in combination with isoniazid as a 12-week once-weekly regimen for the treatment of latent tuberculosis infection.

• Rifapex in combination with isoniazid is not recommended for Individuals presumed to be exposed to rifamycin-or -isoniazid resistant M. tuberculosis.

Dosage In Active Pulmonary Tuberculosis

Rifapex is only recommended for the treatment of active pulmonary tuberculosis caused by drug-susceptible organisms as part of regimens consisting of a 2 month initial phase followed by a 4 month continuation phase. Rifapex should not be used in the treatment of active pulmonary tuberculosis caused by rifampin-resistant strains.

Initial phase (2 Months)

Rifapex should be administered at a dose of 600 mg twice weekly for two months as directly observed therapy (DOT), with an interval of no less than 3 consecutive days (72 hours) between doses, in combination with other anti-tuberculosis drugs as part of an appropriate regimen which includes daily companion drugs such as isoniazid (INH), ethambutol (EMB) and pyrazinamide (PZA).

Continuation phase (4 Months)

Following the initial phase (2 months), continuation phase (4 months) treatment consists of Rifapex 600 mg once-weekly for 4 months in combination with isoniazid or another appropriate anti-tuberculosis agent for susceptible organisms administered as directly observed therapy.

Dosage In Latent Tuberculosis Infection

Rifapex should be administered once-weekly in combination with isoniazid for 12 weeks as directly observed therapy.

Adults and children 12 years and older

The recommended dose of Rifapex should be determined based on weight of the patient up to a maximum of 900 mg once-weekly (see Table 1). The recommended dose of isoniazid is 15 mg/kg (rounded to the nearest 50 mg or 100mg) up to a maximum of 900 mg once-weekly for 12 weeks.

Children 2-11 years

The recommended dose of Rifapex should be determined based on weight of the patient up to a maximum of 900 mg once-weekly (see Table 1). The recommended dose of isoniazid is 25 mg/kg (rounded to the nearest 50 mg or 100mg) up to a maximum of 900 mg once-weekly for 12 weeks.

Table 1: Weight based dose of Rifapex in the treatment of latent tuberculosis infection

Administration

Take Rifapex with meals. Administration of Rifapex with a meal increases oral bioavailability and may reduce the incidence of gastrointestinal upset, nausea, and/or vomiting..

For patients who cannot swallow tablets, the tablets may be crushed and added to a small amount of semi-solid food, all of which should be consumed immediately.

Hypersensitivity

Rifapex is contraindicated in patients with a history of hypersensitivity to rifamycins.

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Hepatotoxicity

Elevations of liver transaminases may occur in patients receiving Rifapex. Patients on Rifapex should be monitored for symptoms of liver injury.

Patients with abnormal liver tests and/or liver disease or patients initiating treatment for active pulmonary tuberculosis should only be given Rifapex in cases of necessity and under strict medical supervision. In such patients, obtain serum transaminase levels prior to therapy and every 2-4 weeks while on therapy. Discontinue Rifapex if evidence of liver injury occurs.

Hypersensitivity And Related Reactions

Hypersensitivity reactions may occur in patients receiving Rifapex. Signs and symptoms of these reactions may include hypotension, urticaria, angioedema, acute bronchospasm, conjunctivitis, thrombocytopenia, neutropenia or flu-like syndrome (weakness, fatigue, muscle pain, nausea, vomiting, headache, fever, chills, aches, rash, itching, sweats, dizziness, shortness of breath, chest pain, cough, syncope, palpitations). There have been reports of anaphylaxis.

Monitor patients receiving Rifapex therapy for signs and/or symptoms of hypersensitivity reactions. If these symptoms occur, administer supportive measures and discontinue Rifapex.

Relapse In The Treatment Of Active Pulmonary Tuberculosis

Rifapex has not been evaluated as part of the initial phase treatment regimen in HIV-infected patients with active pulmonary TB.

Do not use Rifapex as a once-weekly continuation phase regimen in HIV-infected patients with active pulmonary tuberculosis because of a higher rate of failure and/or relapse with rifampinresistant organisms.

Higher relapse rates may occur in patients with cavitary pulmonary lesions and/or positive sputum cultures after the initial phase of active tuberculosis treatment and in patients with evidence of bilateral pulmonary disease. Monitor for signs and symptoms of TB relapse in these patients.

Poor adherence to therapy is associated with high relapse rate. Emphasize the importance of compliance with therapy

Drug Interactions

Rifapentine is an inducer of CYP450 enzymes. Concomitant use of rifapentine with other drugs metabolized by these enzymes, such as protease inhibitors, certain reverse transcriptase inhibitors, and hormonal contraception may cause a significant decrease in plasma concentrations and loss of therapeutic effect.

Discoloration Of Body Fluids

Rifapex may produce a red-orange discoloration of body tissues and/or fluids (e.g., skin, teeth, tongue, urine, feces, saliva, sputum, tears, sweat, and cerebrospinal fluid). Contact lenses or dentures may become permanently stained.

Clostridium difficile-Associated Diarrhea

Clostridium difficile-associated diarrhea (CDAD) has been reported with the use of nearly all systemic antibacterial agents, including Rifapex, with severity ranging from mild diarrhea to fatal colitis. Treatment with antibacterial agents can alter the normal flora of the colon and may permit overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial use. Careful medical history is necessary because CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, discontinue antibacterial use not directed against C. difficile if possible. Institute appropriate measures such as fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation as clinically indicated.

Porphyria

Porphyria has been reported in patients receiving rifampin, attributed to induction of delta amino levulinic acid synthetase. Because Rifapex may have similar enzyme induction properties, avoid the use of Rifapex in patients with porphyria.

Patient Counseling Information

Treatment Adherence

Emphasize the importance of compliance with the full course of therapy, and the importance of not missing any doses of Rifapex or companion medications in the treatment of active pulmonary tuberculosis or the treatment of latent tuberculosis infection.

Hypersensitivity Reactions

Inform patients that Rifapex may cause hypersensitivity reactions. Signs and symptoms of this reaction may include a flu-like illness, hypotension, urticaria, angioedema, bronchospasm, conjunctivitis, thrombocytopenia or neutropenia. Anaphylaxis may also occur.

Inform patients of signs and symptoms of hypersensitivity reactions and advise them to stop the medication and contact their healthcare provider if they experience any of these symptoms.

Hepatitis

Instruct patients to stop the medication and notify their physician promptly if they experience any of the following: fever, loss of appetite, malaise, nausea and vomiting, darkened urine, yellowish discoloration of the skin and eyes, and pain or swelling of the joints.

Drug Interactions

Rifapentine may increase the metabolism and decrease the activity of other drugs that are metabolized by the P4503A4 and 2C8/9 pathways. Dosage adjustments of the co-administered drugs may be necessary. Advise patients to discuss with their physician any other medications they are taking before starting treatment with Rifapex.

Concomitant use of Rifapex with protease inhibitors or reverse transcriptase inhibitors may cause a significant decrease in plasma concentrations and loss of therapeutic effect of the protease inhibitor or reverse transcriptase inhibitor.

Rifapentine may reduce the effectiveness of hormonal contraceptives. Advise patients using oral, transdermal patch, or other systemic hormonal contraceptives to change to non-hormonal methods of birth control.

Discoloration Of Body Fluids

Inform the patient that Rifapex produces a reddish coloration of the urine, sweat, sputum, tears, and breast milk. Contact lenses or dentures may be permanently stained..

Administration With Food

Advise patients to take Rifapex with food.

Nursing Mothers

Advise nursing mothers that breastfeeding is not recommended with Rifapex use.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Hepatocellular carcinomas were increased in male NMRI mice (Harlan Winklemann) which were treated orally with rifapentine for two years at or above doses of 5 mg/kg/day (0.04 times the recommended human dose based on body surface area conversions). In a two year rat study, there was an increase in nasal cavity adenomas in Wistar rats treated orally with rifapentine at 40 mg/kg/day (0.6 times human dose based on body surface area conversions).

Rifapentine was negative in the following genotoxicity tests: in vitro gene mutation assay in bacteria (Ames test); in vitro point mutation test in Aspergillus nidulans; in vitro gene conversion assay in Saccharomyces cerevisiae; host-mediated (mouse) gene conversion assay with Saccharomyces cerevisiae; in vitro Chinese hamster ovary cell/hypoxanthineguaninephosphoribosyl transferase (CHO/HGPRT) forward mutation assay; in vitro chromosomal aberration assay utilizing rat lymphocytes; and in vivo mouse bone marrow micronucleus assay.

The 25-desacetyl metabolite of rifapentine was positive in the in vitro mammalian chromosome aberration test in V79 Chinese Hamster cells, but was negative in the in vitro gene mutation assay in bacteria (Ames test), the in vitro Chinese hamster ovary cell/hypoxanthine-guaninephosphoribosyl transferase (CHO/HGPRT) forward mutation assay, and the in vivo mouse bone marrow micronucleus assay. Fertility and reproductive performance were not affected by oral administration of rifapentine to male and female rats at doses of up to 20 mg/kg/day (one-third of the human dose based on body surface area conversions).

Use In Specific Populations

Pregnancy

Pregnancy Category C

Risk Summary

There are no adequate and well controlled trials of Rifapex in pregnant women; however, there are limited pregnancy outcome data reported from women enrolled in clinical trials of various Rifapex treatment regimens for active tuberculosis and latent tuberculosis infection. The reported rate of spontaneous abortion following Rifapex exposure did not represent an increase over the background rate of spontaneous abortion reported in the general population. Further interpretation of these data is limited by the quality of clinical trial adverse event reporting. In animal reproduction and developmental toxicity studies, rifapentine produced fetal harm and was teratogenic at doses less than and similar to the recommended human dose. Because animal studies are not always predictive of human response, Rifapex should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Clinical Considerations

Labor or Delivery

When administered during the last few weeks of pregnancy, rifampin, another rifamycin product, may increase the risk for maternal postpartum hemorrhage and bleeding in the exposed neonate. Monitor prothrombin time of pregnant women and neonates, who are exposed to Rifapex during the last few weeks of pregnancy. Treatment with Vitamin K may be indicated.

Human Data

Fourteen patients with active tuberculosis treated with multiple anti-tuberculosis drugs including Rifapex became pregnant during clinical studies. Six delivered normal infants; four had first trimester spontaneous abortions (of these, one patient abused ethanol and another patient was HIV-infected); one had an elective abortion; and outcome was unknown in three patients. These data are, however, limited by the quality of reporting and confounded by co-morbid medical conditions and multiple anti-tuberculosis drug exposures.

In the trial that compared the safety and effectiveness of Rifapex in combination with isoniazid to isoniazid alone for the treatment of latent tuberculosis infection, a total of 45 (2.5%) women in the Rifapex/isoniazid arm and 71 (4.1%) women in the isoniazid arm became pregnant. Among the 46 total pregnancies in the Rifapex/isoniazid arm, there were 31 live births, six elective abortions, seven spontaneous abortions, and two unknown outcomes. Of the 31 live infants, 21 were reported healthy while in the other ten cases no further details were available. No congenital anomalies were reported. The rate of spontaneous abortion in the Rifapex/isoniazid arm (15%), and the rate of spontaneous abortion in the isoniazid arm (19%), did not represent an increase over the background rate of 15 to 20 percent reported in the general population. Further interpretation of these results is limited by the quality of adverse event reporting.

Animal Data

Animal studies in rats and rabbits revealed embryofetal toxicity in both species. Pregnant rats given oral rifapentine during organogenesis at 40 mg/kg/day (0.6 times the human dose of 600 mg based on body surface area), produced pups with cleft palates, right aortic arch, increased incidence of delayed ossification, and increased numbers of ribs. When rifapentine was administered orally to mated female rats late in gestation, at 20 mg/kg/day (0.3 times the human dose based on body surface area), pup weights and gestational survival (live pups born/pups born) were reduced compared to controls. Increased resorptions and post implantation loss, decreased mean fetal weights, increased numbers of stillborn pups, and slightly increased pup mortality during lactation were also noted. When pregnant rabbits received oral rifapentine at 10 mg/kg to 40 mg/kg (0.3 times to 1.3 times the human dose based on body surface area), major fetal malformations occurred including: ovarian agenesis, pes varus, arhinia, microphthalmia and irregularities of the ossified facial tissues. At the higher dose, there were increases in post-implantation loss and the incidence of stillborn pups.

Nursing Mothers

It is not known whether Rifapex is present in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. Since Rifapex may produce a red-orange discoloration of body fluids, there is a potential for discoloration of breast milk.

A slight increase in rat pup mortality was observed during lactation when dams were dosed late in gestation through lactation.

Pediatric Use

The safety and effectiveness of Rifapex in the treatment of active pulmonary tuberculosis have not been established in pediatric patients under the age of 12.

The safety and effectiveness of Rifapex in combination with isoniazid once-weekly regimen has been evaluated in pediatric patients (2-17 years of age) for the treatment of latent tuberculosis infection. In clinical studies, the safety profile in children was similar to that observed in adult patients.

In a pharmacokinetic study conducted in 2 year to 11 year-old pediatric patients with latent tuberculosis infection, Rifapex was administered once-weekly based on weight (15mg/kg to 30 mg/Kg, up to a maximum of 900 mg). Exposures (AUC) in children 2 years-11 years with latent tuberculosis infection were higher (average 31%) than those observed in adults receiving Rifapex 900mg once-weekly.

Geriatric Use

Clinical studies with Rifapex did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects. In a pharmacokinetic study with Rifapex, no substantial differences in the pharmacokinetics of rifapentine and 25desacetyl metabolite were observed in the elderly compared to younger adults.

The following serious and otherwise important adverse drug reactions are discussed in greater detail in other sections of labeling:

• Hepatotoxicity
• Hypersensitivity
• Discoloration of Body Fluids
• Clostridium difficile-Associated Diarrhea
• Porphyria

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Active Pulmonary Tuberculosis

Rifapex was studied in a randomized, open label, active-controlled trial of HIV-negative patients with active pulmonary tuberculosis. The population consisted of primarily of male subjects with a mean age of 37 ± 11 years. In the initial 2 month phase of treatment, 361 patients received Rifapex 600 mg twice a week in combination with daily isoniazid, pyrazinamide, and ethambutol and 361 subjects received rifampin in combination with isoniazid, pyrazinamide and ethambutol all administered daily. Ethambutol was discontinued when drug susceptibly testing was known. During the 4 month continuation phase, 317 patients in the Rifapex group continued to receive Rifapex 600 mg dosed once-weekly with isoniazid and 304 patients in the rifampin group received twice weekly rifampin and isoniazid. Both treatment groups received pyridoxine (Vitamin B6) over the 6 month treatment period.

Because Rifapex was administered as part of a combination regimen, the adverse reaction profile reflects the entire regimen.

Twenty-two deaths occurred in the study, eleven in the rifampin combination therapy group and eleven in the Rifapex combination therapy group. 18/361 (5%) rifampin combination therapy patients discontinued the study due to an adverse reaction compared to 11/361 (3%) Rifapex combination therapy patients. Three patients (two rifampin combination therapy patients and one Rifapex combination therapy patient) were discontinued in the initial phase due to hepatotoxicity. Concomitant medications for all three patients included isoniazid, pyrazinamide, ethambutol, and pyridoxine. All three recovered without sequelae.

Five patients had adverse reactions associated with Rifapex overdose. These reactions included hematuria, neutropenia, hyperglycemia, ALT increased, hyperuricemia, pruritus, and arthritis.

Table 2 presents selected treatment-emergent adverse reactions associated with the treatment regimens which occurred in at least 1% of patients during treatment and post-treatment through the first three months of follow-up.

Table 2: Selected Treatment Emergent Adverse Reactions During Treatment of Active Pulmonary Tuberculosis and Through Three Months Follow-up

The following selected treatment-emergent adverse reactions were reported in less than 1% of the Rifapex combination therapy patients during treatment and post-treatment through the first three months of follow-up.

Blood and Lymphatics: lymphocytosis, hematoma, purpura, thrombosis.

Cardiovascular: syncope, tachycardia, palpitation, orthostatic hypotension, pericarditis.

Metabolic & Nutritional: BUN increased, alkaline phosphatase increased.

Gastrointestinal: gastritis, esophagitis, pancreatitis, salivary gland enlargement.

General: asthenia, facial edema.

Hepatobiliary: bilirubinemia, hepatomegaly, jaundice.

Infectious Disease: infection fungal.

Musculoskeletal: myalgia, myositis.

Neurologic: somnolence, dysphonia.

Pregnancy, Puerperium and Perinatal conditions: abortion

Psychiatric: anxiety, confusion

Reproductive Disorders: vaginitis, vaginal hemorrhage, leukorrhea.

Respiratory: dyspnea, pneumonitis, pulmonary fibrosis, asthma, bronchospasm, laryngeal edema, laryngitis.

Skin: urticaria, skin discoloration,

In another randomized, open-label trial, 1075 HIV non-infected and infected patients with active pulmonary tuberculosis who had completed an initial 2 month phase of treatment with 4 drugs were randomly assigned to receive either Rifapex 600 mg and isoniazid once weekly or rifampin and isoniazid twice weekly for the 4 month continuation phase. 502 HIV non-infected and 36 HIV-infected patients were randomized to receive the Rifapex regimen and 502 HIVnoninfected and 35 HIV-infected patients were randomized to receive the rifampin regimen. The death rate was 6.5% for the Rifapex combination regimen compared to 6.7% for the rifampin combination regimen.

Latent Tuberculosis Infection

Main Study

Rifapex in combination with isoniazid given once-weekly for 3 months (3RPT/INH) was compared to isoniazid given once daily for 9 months (9INH) in an open-label, randomized trial in patients with a positive tuberculin skin test, and at high risk for progression from latent tuberculosis infection to active tuberculosis disease. Rifapex was dosed by weight, and isoniazid mg/kg dose was determined according to age to a maximum of 900 mg each.

A total of 4040 patients received at least one dose of the 3RPT/INH regimen, including 348 children 2-17 years of age and 105 HIV-infected individuals. A total of 3759 received at least one dose of the 9INH regimen, including 342 children 2 years-17 years of age and 95 HIV-infected individuals.

Patients were followed for 33 months from the time of enrollment. Treatment-emergent adverse reactions were defined as those occurring during treatment and 60 days after the last dose of treatment. 161 (4%) 3RPT/INH subjects had a rifamycin hypersensitivity reaction, defined as either: a) one of the following: hypotension, urticaria, angioedema, acute bronchospasm, or conjunctivitis occurring in relation to study drug or b) at least four of the following symptoms occurring in relation to the study drug, with at least one symptom being CTCAE Grade 2 or higher: weakness, fatigue, nausea, vomiting, headache, fever, aches, sweats, dizziness, shortness of breath, flushing or chills. No specific definition was used for isoniazid hypersensitivity; 18 (0.5%) 9INH subjects were classified as having a hypersensitivity reaction. Hepatotoxicity was defined as AST ≥ 3x upper limit of normal in the presence of specific signs and symptoms of hepatitis, or AST > 5x upper limit of normal regardless of signs or symptoms. 113 (3%) 9INH subjects and 24 (0.6%) 3RPT/INH subjects developed hepatotoxicity.

196 subjects (4.9%) in the 3RPT/INH arm discontinued treatment due to a treatment related adverse reaction patients and 142 (3.8%) in the 9INH arm discontinued treatment due to a treatment related adverse reaction. In the 3RPT/INH group, the most frequent treatment related adverse reaction resulting in treatment discontinuation was hypersensitivity reaction, occurring in 120 (3%) patients. In the 9INH group, the most frequent treatment related adverse reaction resulting in treatment discontinuation was hepatotoxicity, occurring in 76 (2%) patients.

Seventy one deaths occurred, 31/4040, 0.77% in the 3RPT/INH group and 40/3759 (1.06%) in the 9INH group) during the 33 month study period. During the treatment emergent period, 11 deaths occurred, 4 in the 3RPT/INH group and 7 in the 9INH group. None of the reported deaths were considered related to treatment with study drugs or were attributed to tuberculosis disease.

Table 3 presents select adverse reactions that occurred during the treatment emergent period in the main study in LTBI patients treated with 3RPT/INH or 9INH at a frequency greater than 0.5%.

Table 3 : Select Adverse Reactions occurring in 0.5% or greater of patients* in the Latent Tuberculosis Infection Main Study

Pediatric Substudy

Six-hundred and ninety children 2 years-17 years of age received at least one dose of study drugs in the main study. An additional 342 children 2 years-17 years of age received at least one dose in the pediatric extension study (total 1032 children; 539 received 3RPT/INH and 493 received 9INH).

No children in either treatment arm developed hepatotoxicity. Using the same definition for rifamycin hypersensitivity reaction as in the main study, 7 (1.3%) of children in the 3RPT/INH group experienced a rifamycin hypersensitivity reaction. Adverse reactions in children 2 years11 years of age and 12 years-17 years of age were similar.

HIV Substudy

Two-hundred HIV-infected patients with latent tuberculosis infection received at least one dose of study drugs in the main study and an additional 193 patients received at least one dose in the extension study (total of 393; 207 received 3RPT/INH and 186 received 9INH). Compared to the HIV-negative patients enrolled in the main study, a higher proportion of HIV-infected patients in each treatment arm experienced a treatment emergent adverse reaction, including a higher incidence of hepatotoxicity. Hepatotoxicity occurred in 3/207 (1.5%) patients in the 3RPT/INH arm and in 14/186 (7.5%) in the 9INH arm. Rifamycin hypersensitivity occurred in only one HIV-infected patient.

Eleven deaths occurred during the 33 month follow up period (6/207 in the 3RPT/INH group and 5/186 in the 9INH group) including one death in the 9INH arm during the treatment emergent period. None of the reported deaths were considered related to treatment with study drugs or tuberculosis disease.

Selected treatment-emergent adverse reactions reported during treatment and 60 days posttreatment in less 0.5% of the 3RPT/INH combination-therapy group in the main study are presented below by body system.

Eye Disorders: conjunctivitis.

Blood and Lymphatic System Disorders: leukopenia, anemia, lymphadenopathy, neutropenia.

Gastrointestinal Disorders: nausea, diarrhea, vomiting, abdominal pain constipation, dry mouth, dyspepsia, esophageal irritation, gastritis, pancreatitis.

General Disorders and Administration Site Conditions: fatigue, pyrexia, asthenia, chest pain, chills, feeling jittery.

Infections and Infestations: pharyngitis, viral infection, vulvovaginal candidiasis.

Metabolism and Nutrition Disorders: hyperglycemia, gout, hyperkalemia, decreased appetite, hyperlipidemia.

Musculoskeletal and Connective Tissue Disorders: arthralgia, myalgia, back pain, rhabdomyolysis.

Nervous system Disorders: dizziness, convulsion, paresthesia, headache, neuropathy peripheral, syncope.

Psychiatric Disorders: depression, anxiety, disorientation, suicidal ideation.

Renal and Urinary Disorders: azotemia.

Reproductive System and Breast Disorders: vulvovaginal pruritus.

Respiratory, Thoracic and Mediastinal Disorders: cough, dyspnea, oropharyngeal pain, asthma, bronchial hyperactivity, epistaxis.

Skin and Subcutaneous Tissue Disorders: rash, hyperhidrosis, pruritus, urticaria.

While there is no experience with the treatment of acute overdose with Rifapex, clinical experience with rifamycins suggests that gastric lavage to evacuate gastric contents (within a few hours of overdose), followed by instillation of an activated charcoal slurry into the stomach, may help adsorb any remaining drug from the gastrointestinal tract.

Rifapentine and 25-desacetyl rifapentine are 97.7% and 93.2% plasma protein bound, respectively. Rifapentine and related compounds excreted in urine account for only 17% of the administered dose, therefore, neither hemodialysis nor forced diuresis is expected to enhance the systemic elimination of unchanged rifapentine from the body of a patient with Rifapex overdose.

When oral doses of Rifapex were administered once daily or once every 72 hours to healthy volunteers for 10 days, single dose AUC (0-∞) of rifapentine was similar to its steady-state AUCss (0-24h) or AUCss (0-72h) values, suggesting no significant auto-induction effect on steady-state pharmacokinetics of rifapentine. Steady-state conditions were achieved by day 10 following daily administration of Rifapex 600 mg. No plasma accumulation of rifapentine and 25desacetyl rifapentine (active metabolite) is expected after once weekly administration of Rifapex.

The pharmacokinetic parameters of rifapentine and 25-desacetyl rifapentine on day 10 following oral administration of 600 mg Rifapex every 72 hours to healthy volunteers are described in Table 5.

Table 5: Pharmacokinetics and Rifapentine and 25-Desacetyl Rifapentine in Healthy Volunteers.

The pharmacokinetic parameters of rifapentine and 25-desacetyl rifapentine following single-dose oral administration of 900 mg Rifapex in combination with 900 mg isoniazid in fed conditions are described in Table 6.

Table 6: Mean ± SD Pharmacokinetic Parameters of Rifapentine and 25-Desacetyl Rifapentine in Healthy Volunteers When Rifapex is Co-administered with Isoniazid Under Fed Conditions (N=16).

Absorption

The absolute bioavailability of Rifapex has not been determined. The relative bioavailability (with an oral solution as a reference) of Rifapex after a single 600 mg dose to healthy adult volunteers was 70%. The maximum concentrations were achieved from 5 hours to 6 hours after administration of the 600 mg Rifapex dose.

The administration of Rifapex with a high fat meal increased rifapentine Cmax and AUC by 40% to 50% over that observed when Rifapex was administered under fasting conditions.

The administration of Rifapex (900 mg single dose) and isoniazid (900 mg single dose) with a low fat, high carbohydrate breakfast, led to a 47% and 51% increase in rifapentine Cmax and AUC, respectively. In contrast, the ingestion of the same meal decreased isoniazid Cmax and AUC by 46% and of 23%, respectively.

Distribution

In a population pharmacokinetic analysis in 351 tuberculosis patients who received 600 mg Rifapex in combination with isoniazid, pyrazinamide and ethambutol, the estimated apparent volume of distribution was 70.2 ± 9.1 L. In healthy volunteers, rifapentine and 25-desacetyl rifapentine were 97.7% and 93.2% bound to plasma proteins, respectively. Rifapentine was mainly bound to albumin. Similar extent of protein binding was observed in healthy volunteers, asymptomatic HIV-infected subjects and hepatically impaired subjects.

Metabolism/Excretion

Following a single 600 mg oral dose of radiolabeled rifapentine to healthy volunteers (n=4), 87% of the total ¹⁴C rifapentine was recovered in the urine (17%) and feces (70%). Greater than 80% of the total ¹⁴C rifapentine dose was excreted from the body within 7 days. Rifapentine was hydrolyzed by an esterase enzyme to form a microbiologically active 25-desacetyl rifapentine. Rifapentine and 25-desacetyl rifapentine accounted for 99% of the total radioactivity in plasma. Plasma AUC(0-∞) and Cmax values of the 25-desacetyl rifapentine metabolite were one-half and one-third those of the rifapentine, respectively. Based upon relative in vitro activities and AUC(0∞) values, rifapentine and 25-desacetyl rifapentine potentially contributes 62% and 38% to the clinical activities against M. tuberculosis, respectively.