MEPRON

Warnings and Precautions, Severe Cutaneous Adverse Reactions ( 5.3 ) 3/2026

1 INDICATIONS AND USAGE MEPRON oral suspension is a quinone antimicrobial drug indicated for: • Prevention of Pneumocystis jirovecii pneumonia (PCP) in adults and adolescents aged 13 years and older who cannot tolerate trimethoprim-sulfamethoxazole (TMP-SMX). ( 1.1 ) • Treatment of mild-to-moderate PCP in adults and adolescents aged 13 years and older who cannot tolerate TMP-SMX. ( 1.2 ) Limitations of Use ( 1.3 ) : • Treatment of severe PCP (alveolar arterial oxygen diffusion gradient [(A-a)DO 2 ] >45 mm Hg) with MEPRON has not been studied. • The efficacy of MEPRON in subjects who are failing therapy with TMP-SMX has also not been studied. 1.1 Prevention of Pneumocystis jirovecii Pneumonia MEPRON oral suspension is indicated for the prevention of Pneumocystis jirovecii pneumonia (PCP) in adults and adolescents (aged 13 years and older) who cannot tolerate trimethoprim-sulfamethoxazole (TMP-SMX). 1.2 Treatment of Mild-to-Moderate Pneumocystis jirovecii Pneumonia MEPRON oral suspension is indicated for the acute oral treatment of mild-to-moderate PCP in adults and adolescents (aged 13 years and older) who cannot tolerate TMP-SMX. 1.3 Limitations of Use Clinical experience with MEPRON for the treatment of PCP has been limited to subjects with mild-to-moderate PCP (alveolar-arterial oxygen diffusion gradient [(A-a)DO 2 ] ≤45 mm Hg). Treatment of more severe episodes of PCP with MEPRON has not been studied. The efficacy of MEPRON in subjects who are failing therapy with TMP-SMX has also not been studied.

2 DOSAGE AND ADMINISTRATION • Prevention of PCP: 1,500 mg (10 mL) once daily with food ( 2.1 ) • Treatment of PCP: 750 mg (5 mL) twice daily with food for 21 days ( 2.2 ) • Supplied in foil pouches and bottles: o Foil Pouch: For a 5-mL dose, take entire contents by mouth either by dispensing into a spoon or cup or directly into the mouth. For a 10-mL dose, take entire contents of 2 pouches. ( 2.3 ) o Bottle: Shake bottle gently before use. ( 2.3 ) 2.1 Dosage for the Prevention of P. jirovecii Pneumonia The recommended oral dosage is 1,500 mg (10 mL) once daily administered with food. 2.2 Dosage for the Treatment of Mild-to-Moderate P. jirovecii Pneumonia The recommended oral dosage is 750 mg (5 mL) twice daily (total daily dose = 1,500 mg) administered with food for 21 days. 2.3 Important Administration Instructions Administer MEPRON oral suspension with food to avoid low plasma atovaquone concentrations that may limit response to therapy [see Warnings and Precautions ( 5.1 ), Clinical Pharmacology ( 12.3 )]. MEPRON Foil Pouch • Open each 5-mL pouch by folding along the dotted line and tearing open at horizontal slit as directed by arrow on pouch. • For a 5-mL dose, take entire contents either by placing directly into the mouth or by dispensing into a dosing spoon (5 mL) or cup prior to administration by mouth. • For a 10-mL dose, take the entire contents of 2 pouches. MEPRON Bottle Shake bottle gently before administering the recommended dosage.

3 DOSAGE FORMS AND STRENGTHS MEPRON is a bright yellow, citrus-flavored, oral suspension containing 750 mg of atovaquone per 5 mL. MEPRON is supplied in 210-mL bottles or 5-mL foil pouches. Oral suspension: 750 mg per 5 mL ( 3 )

4 CONTRAINDICATIONS MEPRON oral suspension is contraindicated in patients who develop or have a history of hypersensitivity reactions to atovaquone or any of the components of MEPRON [see Warnings and Precautions ( 5.3 ), Adverse Reactions ( 6.2 )] . Known serious allergic/hypersensitivity reaction to atovaquone or any of the components of MEPRON. ( 4 )

6 ADVERSE REACTIONS The following adverse reactions are discussed in another section of the labeling: • Hepatotoxicity [see Warnings and Precautions ( 5.2 )]. • Severe Cutaneous Adverse Reactions [see Warnings and Precautions ( 5.3 )] . • PCP Prevention: The most frequent adverse reactions (≥25% that required discontinuation) were diarrhea, rash, headache, nausea, and fever. ( 6.1 ) • PCP Treatment: The most frequent adverse reactions (≥14% that required discontinuation) were rash (including maculopapular), nausea, diarrhea, headache, vomiting, and fever. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact GlaxoSmithKline at 1-888-825-5249 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 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 with rates in the clinical trials of another drug and may not reflect the rates observed in practice. Additionally, because many subjects who participated in clinical trials with MEPRON had complications of advanced human immunodeficiency virus (HIV) disease, it was often difficult to distinguish adverse reactions caused by MEPRON from those caused by underlying medical conditions. PCP Prevention Trials In 2 clinical trials, MEPRON oral suspension was compared with dapsone or aerosolized pentamidine in HIV-1–infected adolescent (13 to 18 years) and adult subjects at risk of PCP (CD4 count 2%) of Subjects with Selected Adverse Reactions Requiring Discontinuation of Treatment in the Dapsone Comparative PCP Prevention Trial Adverse Reaction All Subjects MEPRON Oral Suspension 1,500 mg/day (n = 536) % Dapsone 100 mg/day (n = 521) % Rash 6.3 8.8 Nausea 4.1 0.6 Diarrhea 3.2 0.2 Vomiting 2.2 0.6 Aerosolized Pentamidine Comparative Trial: In the aerosolized pentamidine comparative trial (n = 549), the majority of subjects were white (79%), male (92%), and were primary prophylaxis patients at enrollment (58%); the mean age was 38 years. Subjects received MEPRON oral suspension once daily at a dose of 750 mg (n = 188) or 1,500 mg (n = 175) or received aerosolized pentamidine 300 mg every 4 weeks (n = 186); the median durations of exposure were 6.2, 6.0, and 7.8 months, respectively. Table 2 summarizes the clinical adverse reactions reported by ≥20% of the subjects receiving either the 1,500-mg dose of MEPRON oral suspension or aerosolized pentamidine. Rash occurred more often in subjects treated with MEPRON oral suspension (46%) than in subjects treated with aerosolized pentamidine (28%). Treatment‐limiting adverse reactions occurred in 25% of subjects treated with MEPRON oral suspension 1,500 mg once daily and in 7% of subjects treated with aerosolized pentamidine. The most frequent adverse reactions requiring discontinuation of dosing in the group receiving MEPRON oral suspension 1,500 mg once daily were rash (6%), diarrhea (4%), and nausea (3%). The most frequent adverse reaction requiring discontinuation of dosing in the group receiving aerosolized pentamidine was bronchospasm (2%). Table 2. Percentage (≥20%) of Subjects with Selected Adverse Reactions in the Aerosolized Pentamidine Comparative PCP Prevention Trial Adverse Reaction MEPRON Oral Suspension 1,500 mg/day (n = 175) % Aerosolized Pentamidine (n = 186) % Diarrhea 42 35 Rash 39 28 Headache 28 22 Nausea 26 23 Fever 25 18 Rhinitis 24 17 Other reactions occurring in ≥10% of subjects receiving the recommended dose of MEPRON oral suspension (1,500 mg once daily) included vomiting, sweating, flu syndrome, sinusitis, pruritus, insomnia, depression, and myalgia. PCP Treatment Trials Safety information is presented from 2 clinical efficacy trials of the MEPRON tablet formulation: 1) a randomized, double‐blind trial comparing MEPRON tablets with TMP‐SMX in subjects with acquired immunodeficiency syndrome (AIDS) and mild‐to‐moderate PCP [(A-a)DO 2 ] ≤45 mm Hg and PaO 2 ≥60 mm Hg on room air; 2) a randomiz …

7 DRUG INTERACTIONS • Concomitant administration of rifampin or rifabutin reduces atovaquone concentrations; concomitant use with MEPRON oral suspension is not recommended. ( 7.1 ) • Concomitant administration of tetracycline reduces atovaquone concentrations; use caution when coadministering. Monitor patients for potential loss of efficacy of MEPRON if coadministration of tetracycline is necessary. ( 7.2 ) • Concomitant administration with metoclopramide reduces atovaquone concentrations; administer concomitantly only if other antiemetics are not available. ( 7.3 ) • Concomitant administration of indinavir reduces indinavir trough concentrations; use caution when coadministering. Monitor patients for potential loss of efficacy of indinavir if coadministration is necessary. ( 7.4 ) 7.1 Rifampin/Rifabutin Concomitant administration of rifampin or rifabutin and MEPRON oral suspension is known to reduce atovaquone concentrations [see Clinical Pharmacology ( 12.3 )] . Concomitant administration of MEPRON oral suspension and rifampin or rifabutin is not recommended. 7.2 Tetracycline Concomitant administration of tetracycline and MEPRON oral suspension has been associated with a reduction in plasma concentrations of atovaquone [see Clinical Pharmacology ( 12.3 )]. Caution should be used when prescribing tetracycline concomitantly with MEPRON oral suspension. Monitor patients for potential loss of efficacy of MEPRON if coadministration is necessary. 7.3 Metoclopramide Metoclopramide may reduce the bioavailability of atovaquone and should be used only if other antiemetics are not available [see Clinical Pharmacology ( 12.3 )]. 7.4 Indinavir Concomitant administration of atovaquone and indinavir did not result in any change in the steady-state AUC and C max of indinavir but resulted in a decrease in the C trough of indinavir [see Clinical Pharmacology ( 12.3 )]. Caution should be exercised when prescribing MEPRON oral suspension with indinavir due to the decrease in trough concentrations of indinavir. Monitor patients for potential loss of efficacy of indinavir if coadministration with MEPRON oral suspension is necessary.

8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy Risk Summary Available data from postmarketing experience with use of MEPRON in pregnant women are insufficient to identify a drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes. Pregnant women with HIV who are infected with PCP are at increased risk of adverse pregnancy outcomes (see Clinical Considerations) . Atovaquone given orally by gavage to pregnant rats and rabbits during organogenesis did not cause fetal malformations at plasma concentrations up to 3 times and 0.5 times, respectively, the estimated human exposure based on steady-state plasma concentrations (see Data) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk: Pregnant women with HIV who are infected with PCP are at increased risk of severe illness and maternal death associated with PCP compared with non-pregnant women. Data Animal Data: Atovaquone administered in oral doses of 250, 500, and 1,000 mg/kg/day to pregnant rats during organogenesis (Gestation Day [GD] 6 to GD15) did not cause maternal or embryo-fetal toxicity at doses up to 1,000 mg/kg/day corresponding to maternal plasma concentrations approximately 3 times the estimated human exposure during the treatment of PCP based on steady-state plasma concentrations. In pregnant rabbits, atovaquone administered in oral doses of 300, 600, and 1,200 mg/kg/day during organogenesis (GD6 to GD18) caused decreased fetal body length at a maternally toxic dose of 1,200 mg/kg/day corresponding to a plasma concentration that is approximately 0.5 times the estimated human exposure based on steady-state plasma concentrations. In a pre- and post-natal study in rats, atovaquone administered in oral doses of 250, 500, and 1,000 mg/kg/day from GD15 until Lactation Day (LD) 20 did not impair the growth or developmental effects in first generation offspring at doses up to 1,000 mg/kg/day corresponding to approximately 3 times the estimated human exposure based on steady-state plasma concentrations during the treatment of PCP. Atovaquone crossed the placenta and was present in fetal rat and rabbit tissue. 8.2 Lactation Risk Summary There are no data on the presence of atovaquone in human milk, the effects on the breastfed child, or the effects on milk production. Atovaquone was detected in rat milk when lactating rats were administered oral atovaquone (see Data) . When a drug is present in animal milk, it is likely the drug will be present in human milk. For women with HIV‐1, potential risks of breastfeeding include HIV‐1 transmission (in infants without HIV‐1). The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for MEPRON and any potential adverse effects on the breastfed child from MEPRON or from the underlying maternal condition. Data In a rat study with doses of 10 and 250 mg/kg given orally by gavage on postpartum Day 11, atovaquone concentrations in the milk were 30% of the concurrent atovaquone concentrations in the maternal plasma at both doses. The concentration of drug in animal milk does not necessarily predict the concentration of drug in human milk. 8.4 Pediatric Use Evidence of safety and effectiveness in pediatric patients (aged 12 years and younger) has not been established. In a trial of MEPRON oral suspension administered once daily with food for 12 days to 27 HIV-1–infected, asymptomatic infants and children aged between 1 month and 13 years, the pharmacokinetics of atovaquone were age-dependent. The average steady-state plasma atovaquone concentrations in the 24 subj …

12.1 Mechanism of Action Atovaquone is a quinone antimicrobial drug [see Microbiology ( 12.4 )] .

11 DESCRIPTION MEPRON (atovaquone oral suspension) is a quinone antimicrobial drug. The chemical name of atovaquone is trans -2-[4-(4-chlorophenyl)cyclohexyl]-3-hydroxy-1,4-naphthalenedione. Atovaquone is a yellow crystalline solid that is practically insoluble in water. It has a molecular weight of 366.84 and the molecular formula C 22 H 19 ClO 3 . The compound has the following structural formula: MEPRON oral suspension is a formulation of micro‐fine particles of atovaquone. Each 5 mL of MEPRON oral suspension contains 750 mg of atovaquone and the inactive ingredients benzyl alcohol, flavor, poloxamer 188, purified water, saccharin sodium, and xanthan gum. atovaquone molecular chemical structure

10 OVERDOSAGE Overdoses up to 31,500 mg of atovaquone have been reported. In one such patient who also took an unspecified dose of dapsone, methemoglobinemia occurred. Rash has also been reported after overdose. There is no known antidote for atovaquone, and it is currently unknown if atovaquone is dialyzable.

16 HOW SUPPLIED/STORAGE AND HANDLING MEPRON oral suspension (bright yellow, citrus-flavored) containing 750 mg atovaquone per 5 mL. • Bottle of 210 mL with child-resistant cap (NDC 0173-0665-18). Store at 15°C to 25°C (59°F to 77°F). Do not freeze . Dispense in tight container as defined in USP. • 5-mL child‐resistant foil pouch ‐ unit dose pack of 42 (NDC 0173-0547-00). Store at 15°C to 25°C (59°F to 77°F). Do not freeze .