Ambrisentan Tablet, Film Coated
FDA Label NDC 0378-4271

Ambrisentan tablets are contraindicated for use during pregnancy because they may cause major birth defects if used by pregnant patients, based on studies in animals [see Contraindications (4.1), Warnings and Precautions (5.1), and Use in Specific Populations (8.1)].

Therefore, for females of reproductive potential, exclude pregnancy before the initiation of treatment with ambrisentan tablets. Advise use of effective contraception before initiation, during treatment, and for one month after treatment with ambrisentan tablets [see Dosage and Administration (2.2), Contraindications (4.1), Warnings and Precautions (5.1), and Use in Specific Populations (8.1, 8.3)]. When pregnancy is detected, discontinue ambrisentan tablets as soon as possible (5.1).

Ambrisentan tablets are indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1) in adult patients:

• To improve exercise ability and delay clinical worsening.

Studies establishing effectiveness included predominantly patients with WHO Functional Class II-III symptoms and etiologies of idiopathic or heritable PAH (60%) or PAH associated with connective tissue diseases (34%).

Initiate treatment at 5 mg once daily. At 4-week intervals, the dose of ambrisentan tablets can be increased, as needed and tolerated, to 10 mg.

Do not split, crush, or chew tablets.

Exclude pregnancy before initiating treatment with ambrisentan tablets in females of reproductive potential [see Warnings and Precautions (5.1), Use in Specific Populations (8.1, 8.3)].

Ambrisentan Tablets are available containing 5 mg or 10 mg of ambrisentan.

• The 5 mg tablets are pink, film-coated, round, unscored tablets debossed with M on one side of the tablet and AN on the other side.
• The 10 mg tablets are pink, film-coated, capsule shaped, unscored tablets debossed with M on one side of the tablet and AN1 on the other side.

Ambrisentan tablets may cause fetal harm when administered to a pregnant female. Ambrisentan tablets are contraindicated in females who are pregnant. Ambrisentan tablets were consistently shown to have teratogenic effects when administered to animals. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus [see Dosage and Administration (2.2), Warnings and Precautions (5.1), and Use in Specific Populations (8.1)].

Ambrisentan tablets are contraindicated in patients with Idiopathic Pulmonary Fibrosis (IPF), including IPF patients with pulmonary hypertension (WHO Group 3) [see Clinical Studies (14.4)].

Based on data from animal reproduction studies, ambrisentan tablets may cause fetal harm when administered during pregnancy and are contraindicated during pregnancy. The available human data for endothelin receptor antagonists do not establish the presence or absence of major birth defects related to the use of ambrisentan tablets. Advise patients who can become pregnant of the potential risk to a fetus. Obtain a pregnancy test prior to initiation of treatment with ambrisentan tablets. Advise patients who can become pregnant to use effective contraception prior to initiation of treatment, during treatment, and for one month after discontinuation of treatment with ambrisentan tablets. When pregnancy is detected, discontinue use as soon as possible [see Dosage and Administration (2.2), and Use in Specific Populations (8.1, 8.3)].

Peripheral edema is a known class effect of endothelin receptor antagonists, and is also a clinical consequence of PAH and worsening PAH. In the placebo-controlled studies, there was an increased incidence of peripheral edema in patients treated with doses of 5 or 10 mg ambrisentan tablets compared to placebo [see Adverse Reactions (6.1)]. Most edema was mild to moderate in severity.

In addition, there have been postmarketing reports of fluid retention in patients with pulmonary hypertension, occurring within weeks after starting ambrisentan tablets. Patients required intervention with a diuretic, fluid management, or, in some cases, hospitalization for decompensating heart failure.

If clinically significant fluid retention develops, with or without associated weight gain, further evaluation should be undertaken to determine the cause, such as ambrisentan tablets or underlying heart failure, and the possible need for specific treatment or discontinuation of ambrisentan tablets therapy.

If patients develop acute pulmonary edema during initiation of therapy with vasodilating agents such as ambrisentan tablets, the possibility of PVOD should be considered, and if confirmed ambrisentan tablets should be discontinued.

Decreased sperm counts have been observed in human and animal studies with another endothelin receptor antagonist and in animal fertility studies with ambrisentan. Ambrisentan tablets may have an adverse effect on spermatogenesis [see Use in Specific Populations (8.6) and Nonclinical Toxicology (13.1)].

Decreases in hemoglobin concentration and hematocrit have followed administration of other endothelin receptor antagonists and were observed in clinical studies with ambrisentan tablets. These decreases were observed within the first few weeks of treatment with ambrisentan tablets, and stabilized thereafter. The mean decrease in hemoglobin from baseline to end of treatment for those patients receiving ambrisentan tablets in the 12-week placebo-controlled studies was 0.8 g/dL.

Marked decreases in hemoglobin (> 15% decrease from baseline resulting in a value below the lower limit of normal) were observed in 7% of all patients receiving ambrisentan tablets (and 10% of patients receiving 10 mg) compared to 4% of patients receiving placebo. The cause of the decrease in hemoglobin is unknown, but it does not appear to result from hemorrhage or hemolysis.

In the long-term open-label extension of the two pivotal clinical studies, mean decreases from baseline (ranging from 0.9 to 1.2 g/dL) in hemoglobin concentrations persisted for up to 4 years of treatment.

There have been postmarketing reports of decreases in hemoglobin concentration and hematocrit that have resulted in anemia requiring transfusion.

Measure hemoglobin prior to initiation of ambrisentan tablets, at one month, and periodically thereafter. Initiation of ambrisentan tablets therapy is not recommended for patients with clinically significant anemia. If a clinically significant decrease in hemoglobin is observed and other causes have been excluded, consider discontinuing ambrisentan tablets.

Clinically significant adverse reactions that appear in other sections of the labeling include:

• Embryo-fetal Toxicity [see Warnings and Precautions (5.1), Use in Specific Populations (8.1)]
• Fluid Retention [see Warnings and Precautions (5.2)]
• Pulmonary Edema with PVOD [see Warnings and Precautions (5.3)]
• Decreased Sperm Count [see Warnings and Precautions (5.4)]
• Hematologic Changes [see Warnings and Precautions (5.5)]

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.

Safety data for ambrisentan tablets are presented from two 12-week, placebo-controlled studies (ARIES-1 and ARIES-2) in patients with pulmonary arterial hypertension (PAH). The exposure to ambrisentan in these studies ranged from 6 days to 100 days.

In ARIES-1 and ARIES-2, a total of 261 patients received ambrisentan tablets at doses of 2.5, 5, or 10 mg once daily and 132 patients received placebo. The adverse reactions that occurred in > 3% more patients receiving ambrisentan tablets than receiving placebo are shown in Table 1.

Most adverse drug reactions were mild to moderate and only nasal congestion was dose-dependent.

Few notable differences in the incidence of adverse reactions were observed for patients by age or sex. Peripheral edema was similar in younger patients (< 65 years) receiving ambrisentan tablets (14%; 29/205) or placebo (13%; 13/104), and was greater in elderly patients (≥ 65 years) receiving ambrisentan tablets (29%; 16/56) compared to placebo (4%; 1/28). The results of such subgroup analyses must be interpreted cautiously.

The incidence of treatment discontinuations due to adverse events other than those related to PAH during the clinical trials in patients with PAH was similar for ambrisentan tablets (2%; 5/261 patients) and placebo (2%; 3/132 patients). The incidence of patients with serious adverse events other than those related to PAH during the clinical trials in patients with PAH was similar for placebo (7%; 9/132 patients) and for ambrisentan tablets (5%; 13/261 patients).

During 12-week controlled clinical trials, the incidence of aminotransferase elevations > 3 x upper limit of normal (ULN) were 0% on ambrisentan tablets and 2.3% on placebo. In practice, cases of hepatic injury should be carefully evaluated for cause.

In an uncontrolled, open-label study, 36 patients who had previously discontinued endothelin receptor antagonists (ERAs: bosentan, an investigational drug, or both) due to aminotransferase elevations > 3 x ULN were treated with ambrisentan tablets. Prior elevations were predominantly moderate, with 64% of the ALT elevations < 5 x ULN, but 9 patients had elevations > 8 x ULN. Eight patients had been re-challenged with bosentan and/or the investigational ERA and all eight had a recurrence of aminotransferase abnormalities that required discontinuation of ERA therapy. All patients had to have normal aminotransferase levels on entry to this study. Twenty-five of the 36 patients were also receiving prostanoid and/or phosphodiesterase type 5 (PDE5) inhibitor therapy. Two patients discontinued early (including one of the patients with a prior 8 x ULN elevation). Of the remaining 34 patients, one patient experienced a mild aminotransferase elevation at 12 weeks on ambrisentan tablets 5 mg that resolved with decreasing the dosage to 2.5 mg, and that did not recur with later escalations to 10 mg. With a median follow-up of 13 months and with 50% of patients increasing the dose of ambrisentan tablets to 10 mg, no patients were discontinued for aminotransferase elevations. While the uncontrolled study design does not provide information about what would have occurred with re-administration of previously used ERAs or show that ambrisentan tablets led to fewer aminotransferase elevations than would have been seen with those drugs, the study indicates that ambrisentan tablets may be tried in patients who have experienced asymptomatic aminotransferase elevations on other ERAs after aminotransferase levels have returned to normal.

The following adverse reactions were identified during post-approval use of ambrisentan tablets. Because these reactions were reported voluntarily from a population of uncertain size, it is not possible to estimate reliably the frequency or to establish a causal relationship to drug exposure: anemia requiring transfusion [see Warnings and Precautions (5.5)], heart failure (associated with fluid retention), symptomatic hypotension, and hypersensitivity (e.g., angioedema, rash).

Elevations of liver aminotransferases (ALT, AST) have been reported with ambrisentan tablets use; in most cases alternative causes of the liver injury could be identified (heart failure, hepatic congestion, hepatitis, alcohol use, hepatotoxic medications). Other endothelin receptor antagonists have been associated with elevations of aminotransferases, hepatotoxicity, and cases of liver failure [see Adverse Reactions (6.1)].

Multiple dose coadministration of ambrisentan and cyclosporine resulted in an approximately 2-fold increase in ambrisentan exposure in healthy volunteers; therefore, limit the dose of ambrisentan to 5 mg once daily when coadministered with cyclosporine [see Clinical Pharmacology (12.3)].

Based on data from animal reproduction studies, ambrisentan tablets may cause fetal harm, including birth defects and fetal death, when administered to a pregnant woman and is contraindicated during pregnancy. There are limited data on ambrisentan tablets use in pregnant women. Available data from postmarketing reports and published literature over decades of use with endothelin receptor antagonists in the same class as ambrisentan tablets have not identified an increased risk of major birth defects; however, these data are limited. Methodological limitations of these postmarketing reports and published literature include lack of a control group; limited information regarding dose, duration, and timing of drug exposure; and missing data. These limitations preclude establishing a reliable estimate of the risk of adverse fetal and neonatal outcomes with maternal endothelin receptor antagonist use. In animal reproduction studies, ambrisentan tablets were teratogenic in rats and rabbits at doses which resulted in exposures of 3.5 and 1.7 times, respectively, the human dose of 10 mg per day [see Animal Data]. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, advise the patient of the potential hazard to a fetus [see Contraindications (4.1), Warnings and Precautions (5.1)].

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 estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.

It is not known whether ambrisentan is present in human milk. Because many drugs are present in human milk and because of the potential for serious adverse reactions in breastfed infants from ambrisentan tablets, a decision should be made whether to discontinue breastfeeding or discontinue ambrisentan tablets, taking into account the importance of the drug to the mother.

Ambrisentan tablets were teratogenic at oral dosages of ≥ 15 mg/kg/day (AUC 51.7 h•µg/mL) in rats and ≥ 7 mg/kg/day (24.7 h•µg/mL) in rabbits; it was not studied at lower dosages. These dosages are of 3.5 and 1.7 times, respectively, the human dose of 10 mg per day (14.8 h•µg/mL) based on AUC. In both species, there were abnormalities of the lower jaw and hard and soft palate, malformation of the heart and great vessels, and failure of formation of the thymus and thyroid.

A preclinical study in rats has shown decreased survival of newborn pups (mid and high dosages) and effects on testicle size and fertility of pups (high dosage) following maternal treatment with ambrisentan from late gestation through weaning. The mid and high dosages were 51 x, and 170 x (on a mg/m² body surface area basis) the maximum oral human dose of 10 mg and an average adult body weight of 70 kg. These effects were absent at a maternal dosage 17 x the human dose based on mg/m².

Based on data from animal reproductive toxicity studies, ambrisentan may cause fetal harm, including birth defects and fetal death, when administered to a pregnant patient and is contraindicated during pregnancy [see Contraindications (4.1), Use in Specific Populations (8.1)].

Verify that patients who can become pregnant are not pregnant prior to initiating ambrisentan. The patient should contact their physician immediately for pregnancy testing if onset of menses is delayed or pregnancy is suspected. If the pregnancy test is positive, the physician and patient should discuss the risks to the pregnancy and the fetus.

Patients who can become pregnant who are using ambrisentan should use effective contraception prior to initiation of treatment, during treatment, and for one month after discontinuation of treatment with ambrisentan to prevent pregnancy [see Warnings and Precautions (5.1)].

In a 6-month study of another endothelin receptor antagonist, bosentan, 25 male patients with WHO functional class III and IV PAH and normal baseline sperm count were evaluated for effects on testicular function. There was a decline in sperm count of at least 50% in 25% of the patients after 3 or 6 months of treatment with bosentan. One patient developed marked oligospermia at 3 months, and the sperm count remained low with 2 follow-up measurements over the subsequent 6 weeks.

Bosentan was discontinued and after 2 months the sperm count had returned to baseline levels. In 22 patients who completed 6 months of treatment, sperm count remained within the normal range and no changes in sperm morphology, sperm motility, or hormone levels were observed. Based on these findings and preclinical data [see Nonclinical Toxicology (13.1)] from endothelin receptor antagonists, it cannot be excluded that endothelin receptor antagonists such as ambrisentan tablets have an adverse effect on spermatogenesis. Counsel patients about the potential effects on fertility [see Warnings and Precautions (5.5)].

Safety and effectiveness of ambrisentan tablets in pediatric patients have not been established.

In juvenile rats administered ambrisentan orally once daily during postnatal day 7 to 26, 36, or 62, a decrease in brain weight (-3% to -8%) with no morphologic or neurobehavioral changes occurred after breathing sounds, apnea, and hypoxia were observed, at exposures approximately 1.8 to 7.0 times human pediatric exposures at 10 mg, based on AUC.

In the two placebo-controlled clinical studies of ambrisentan tablets, 21% of patients were ≥ 65 years old and 5% were ≥ 75 years old. The elderly (age ≥ 65 years) showed less improvement in walk distances with ambrisentan tablets than younger patients did, but the results of such subgroup analyses must be interpreted cautiously. Peripheral edema was more common in the elderly than in younger patients.

The impact of renal impairment on the pharmacokinetics of ambrisentan has been examined using a population pharmacokinetic approach in PAH patients with creatinine clearances ranging between 20 and 150 mL/min. There was no significant impact of mild or moderate renal impairment on exposure to ambrisentan [see Clinical Pharmacology (12.3)]. Dose adjustment of ambrisentan tablets in patients with mild or moderate renal impairment is therefore not required. There is no information on the exposure to ambrisentan in patients with severe renal impairment.

The impact of hemodialysis on the disposition of ambrisentan has not been investigated.

The influence of pre-existing hepatic impairment on the pharmacokinetics of ambrisentan has not been evaluated. Because there is in vitro and in vivo evidence of significant metabolic and biliary contribution to the elimination of ambrisentan, hepatic impairment might be expected to have significant effects on the pharmacokinetics of ambrisentan [see Clinical Pharmacology (12.3)]. Ambrisentan tablets are not recommended in patients with moderate or severe hepatic impairment. There is no information on the use of ambrisentan tablets in patients with mild pre-existing impaired liver function; however, exposure to ambrisentan may be increased in these patients.

Other endothelin receptor antagonists (ERAs) have been associated with aminotransferase (AST, ALT) elevations, hepatotoxicity, and cases of liver failure [see Adverse Reactions (6.1, 6.2)]. In patients who develop hepatic impairment after ambrisentan tablets initiation, the cause of liver injury should be fully investigated. Discontinue ambrisentan tablets if elevations of liver aminotransferases are > 5 x ULN or if elevations are accompanied by bilirubin > 2 x ULN, or by signs or symptoms of liver dysfunction and other causes are excluded.

There is no experience with overdosage of ambrisentan tablets. The highest single dose of ambrisentan tablets administered to healthy volunteers was 100 mg, and the highest daily dose administered to patients with PAH was 10 mg once daily. In healthy volunteers, single doses of 50 mg and 100 mg (5 to 10 times the maximum recommended dose) were associated with headache, flushing, dizziness, nausea, and nasal congestion. Massive overdosage could potentially result in hypotension that may require intervention.

Ambrisentan tablets contain ambrisentan, an endothelin receptor antagonist. The chemical name of ambrisentan is (+)-(2S)-2-[(4,6-dimethylpyrimidin-2-yl)oxy]-3-methoxy-3,3-diphenylpropanoic acid. It has a molecular formula of C₂₂H₂₂N₂O₄ and a molecular weight of 378.42 and has the following structural formula:

Ambrisentan Structural Formula (Image 01)

Ambrisentan is a white to off-white powder. It is a carboxylic acid with a pKa of 4.0. Ambrisentan is practically insoluble in water and in aqueous solutions at low pH. Solubility increases in aqueous solutions at higher pH. In the solid state ambrisentan is very stable, is not hygroscopic, and is not light sensitive.

Ambrisentan tablets are available as 5 mg and 10 mg film-coated tablets for once daily oral administration. The tablets include the following inactive ingredients: anhydrous lactose, croscarmellose sodium, FD&C Blue No. 2 Aluminum Lake, FD&C Red No. 40 Aluminum Lake, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, talc and titanium dioxide. Each round, pink ambrisentan tablet contains 5 mg of ambrisentan. Each capsule shaped, pink ambrisentan tablet contains 10 mg of ambrisentan. Ambrisentan tablets are unscored.

Endothelin-1 (ET-1) is a potent autocrine and paracrine peptide. Two receptor subtypes, ET_A and ET_B, mediate the effects of ET-1 in the vascular smooth muscle and endothelium. The primary actions of ET_A are vasoconstriction and cell proliferation, while the predominant actions of ET_B are vasodilation, antiproliferation, and ET-1 clearance.

In patients with PAH, plasma ET-1 concentrations are increased as much as 10-fold and correlate with increased mean right atrial pressure and disease severity. ET-1 and ET-1 mRNA concentrations are increased as much as 9-fold in the lung tissue of patients with PAH, primarily in the endothelium of pulmonary arteries. These findings suggest that ET-1 may play a critical role in the pathogenesis and progression of PAH.

Ambrisentan is a high-affinity (K_i = 0.011 nM) ET_A receptor antagonist with a high selectivity for the ET_A versus ET_B receptor (> 4000-fold). The clinical impact of high selectivity for ET_A is not known.

In a randomized, positive- and placebo-controlled, parallel-group study, healthy subjects received either ambrisentan tablets 10 mg daily followed by a single dose of 40 mg, placebo followed by a single dose of moxifloxacin 400 mg, or placebo alone. Ambrisentan tablets 10 mg daily had no significant effect on the QTc interval. The 40 mg dose of ambrisentan tablets increased mean QTc at t_max by 5 ms with an upper 95% confidence limit of 9 ms. For patients receiving ambrisentan tablets 5-10 mg daily and not taking metabolic inhibitors, no significant QT prolongation is expected.

The pharmacokinetics of ambrisentan (S-ambrisentan) in healthy subjects is dose proportional. The absolute bioavailability of ambrisentan is not known. Ambrisentan is absorbed with peak concentrations occurring approximately 2 hours after oral administration in healthy subjects and PAH patients. Food does not affect its bioavailability. In vitro studies indicate that ambrisentan is a substrate of P-gp. Ambrisentan is highly bound to plasma proteins (99%). The elimination of ambrisentan is predominantly by non-renal pathways, but the relative contributions of metabolism and biliary elimination have not been well characterized. In plasma, the AUC of 4-hydroxymethyl ambrisentan accounts for approximately 4% relative to parent ambrisentan AUC. The in vivo inversion of S-ambrisentan to R-ambrisentan is negligible. The mean oral clearance of ambrisentan is 38 mL/min and 19 mL/min in healthy subjects and in PAH patients, respectively. Although ambrisentan has a 15-hour terminal half-life, the mean trough concentration of ambrisentan at steady-state is about 15% of the mean peak concentration and the accumulation factor is about 1.2 after long-term daily dosing, indicating that the effective half-life of ambrisentan is about 9 hours.

Studies with human liver tissue indicate that ambrisentan is metabolized by CYP3A, CYP2C19, and uridine 5’-diphosphate glucuronosyltransferases (UGTs) 1A9S, 2B7S, and 1A3S. In vitro studies suggest that ambrisentan is a substrate of the Organic Anion Transporting Polypeptides OATP1B1 and OATP1B3, and P-glycoprotein (P-gp). Drug interactions might be expected because of these factors; however, a clinically relevant interaction has been demonstrated only with cyclosporine [see Drug Interactions (7)]. In vitro studies found ambrisentan to have little to no inhibition of human hepatic transporters. Ambrisentan demonstrated weak dose-dependent inhibition of OATP1B1, OATP1B3, and NTCP (IC₅₀ of 47 μM, 45 μM, and approximately 100 μM, respectively) and no transporter-specific inhibition of BSEP, BRCP, P-gp, or MRP2. Ambrisentan does not inhibit or induce drug metabolizing enzymes at clinically relevant concentrations.

The effects of other drugs on ambrisentan pharmacokinetics and the effects of ambrisentan on the exposure to other drugs are shown in Figure 2 and Figure 3, respectively.

Figure 2 Effects Of Other Drugs On Ambrisentan Pharmacokinetics (Image 02)

Figure 3 Effects Of Ambrisentan On Other Drugs (Image 03)

Oral carcinogenicity studies of up to two years duration were conducted at starting doses of 10, 30, and 60 mg/kg/day in rats (8 to 48 times the maximum recommended human dose [MRHD] on a mg/m² basis) and at 50, 150, and 250 mg/kg/day in mice (28 to 140 times the MRHD). In the rat study, the high- and mid-dose male and female groups had their doses lowered to 40 and 20 mg/kg/day, respectively, in week 51 because of effects on survival. The high-dose males and females were taken off drug completely in weeks 69 and 93, respectively. The only evidence of ambrisentan-related carcinogenicity was a positive trend in male rats, for the combined incidence of benign basal cell tumor and basal cell carcinoma of skin/subcutis in the mid-dose group (high-dose group excluded from analysis), and the occurrence of mammary fibroadenomas in males in the high-dose group. In the mouse study, high-dose male and female groups had their doses lowered to 150 mg/kg/day in week 39 and were taken off drug completely in week 96 (males) or week 76 (females). In mice, ambrisentan was not associated with excess tumors in any dosed group.

Positive findings of clastogenicity were detected, at drug concentrations producing moderate to high toxicity, in the chromosome aberration assay in cultured human lymphocytes. There was no evidence for genetic toxicity of ambrisentan when tested in vitro in bacteria (Ames test) or in vivo in rats (micronucleus assay, unscheduled DNA synthesis assay).

The development of testicular tubular atrophy and impaired fertility has been linked to the chronic administration of endothelin receptor antagonists in rodents. Testicular tubular degeneration was observed in rats treated with ambrisentan for two years at doses ≥ 10 mg/kg/day (8-fold MRHD). Increased incidences of testicular findings were also observed in mice treated for two years at doses ≥ 50 mg/kg/day (28-fold MRHD). Effects on sperm count, sperm morphology, mating performance, and fertility were observed in fertility studies in which male rats were treated with ambrisentan at oral doses of 300 mg/kg/day (236-fold MRHD). At doses of ≥ 10 mg/kg/day, observations of testicular histopathology in the absence of fertility and sperm effects were also present.

Two 12-week, randomized, double-blind, placebo-controlled, multicenter studies were conducted in 393 patients with PAH (WHO Group 1). The two studies were identical in design except for the doses of ambrisentan tablets and the geographic region of the investigational sites. ARIES-1 compared once-daily doses of 5 mg and 10 mg ambrisentan tablets to placebo, while ARIES-2 compared once-daily doses of 2.5 mg and 5 mg ambrisentan tablets to placebo. In both studies, ambrisentan tablets or placebo was added to current therapy, which could have included a combination of anticoagulants, diuretics, calcium channel blockers, or digoxin, but not epoprostenol, treprostinil, iloprost, bosentan, or sildenafil. The primary study endpoint was 6-minute walk distance. In addition, clinical worsening, WHO functional class, dyspnea, and SF-36^® Health Survey were assessed.

Patients had idiopathic or heritable PAH (64%) or PAH associated with connective tissue diseases (32%), HIV infection (3%), or anorexigen use (1%). There were no patients with PAH associated with congenital heart disease.

Patients had WHO functional class I (2%), II (38%), III (55%), or IV (5%) symptoms at baseline. The mean age of patients was 50 years, 79% of patients were female, and 77% were Caucasian.

Results of the 6-minute walk distance at 12 weeks for the ARIES-1 and ARIES-2 studies are shown in Table 3 and Figure 4.

Figure 4 Mean Change In 6-minute Walk Distance (aries-1 And Aries-2) (Image 04)

In both studies, treatment with ambrisentan tablets resulted in a significant improvement in 6-minute walk distance for each dose of ambrisentan tablets and the improvements increased with dose. An increase in 6-minute walk distance was observed after 4 weeks of treatment with ambrisentan tablets, with a dose-response observed after 12 weeks of treatment. Improvements in walk distance with ambrisentan tablets were smaller for elderly patients (age ≥ 65) than younger patients and for patients with secondary PAH than for patients with idiopathic or heritable PAH. The results of such subgroup analyses must be interpreted cautiously.

Time to clinical worsening of PAH was defined as the first occurrence of death, lung transplantation, hospitalization for PAH, atrial septostomy, study withdrawal due to the addition of other PAH therapeutic agents, or study withdrawal due to early escape. Early escape was defined as meeting two or more of the following criteria: a 20% decrease in the 6-minute walk distance; an increase in WHO functional class; worsening right ventricular failure; rapidly progressing cardiogenic, hepatic, or renal failure; or refractory systolic hypotension. The clinical worsening events during the 12-week treatment period of the ambrisentan tablets clinical trials are shown in Table 4 and Figure 5.

There was a significant delay in the time to clinical worsening for patients receiving ambrisentan tablets compared to placebo. Results in subgroups such as the elderly were also favorable.

Figure 5 Time To Clinical Worsening (aries-1 And Aries-2) (Image 05)

In long-term follow-up of patients who were treated with ambrisentan tablets (2.5 mg, 5 mg, or 10 mg once daily) in the two pivotal studies and their open-label extension (N = 383), Kaplan-Meier estimates of survival at 1, 2, and 3 years were 93%, 85%, and 79%, respectively. Of the patients who remained on ambrisentan tablets for up to 3 years, the majority received no other treatment for PAH. These uncontrolled observations do not allow comparison with a group not given ambrisentan tablets and cannot be used to determine the long-term effect of ambrisentan tablets on mortality.

A randomized controlled study in patients with IPF, with or without pulmonary hypertension (WHO Group 3), compared ambrisentan tablets (N = 329) to placebo (N = 163). The study was terminated after 34 weeks for lack of efficacy, and was found to demonstrate a greater risk of disease progression or death on ambrisentan tablets. More patients taking ambrisentan tablets died (8% vs. 4%), had a respiratory hospitalization (13% vs. 6%), and had a decrease in FVC/DLCO (17% vs. 12%) [see Contraindications (4.2)].

Ambrisentan Tablets are available containing 5 mg or 10 mg of ambrisentan.

The 5 mg tablets are pink, film-coated, round, unscored tablets debossed with M on one side of the tablet and AN on the other side. They are available as follows:

NDC 0378-4270-93
bottles of 30 tablets

The 10 mg tablets are pink, film-coated, capsule shaped, unscored tablets debossed with M on one side of the tablet and AN1 on the other side. They are available as follows:

NDC 0378-4271-93
bottles of 30 tablets

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.] Store ambrisentan tablets in their original packaging.

Dispense only in original container.

PHARMACIST: Dispense a Medication Guide with each prescription.

Advise patients to read the FDA-approved patient labeling (Medication Guide).

Embryo-fetal Toxicity
Instruct patients on the risk of fetal harm when ambrisentan tablets are used in pregnancy [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1)]. Instruct females of reproductive potential to immediately contact their physician if they suspect they may be pregnant. Educate and counsel patients who can become pregnant about the need to use effective contraception prior to treatment with ambrisentan tablets, during treatment, and for one month after treatment discontinuation [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1, 8.3)]. Patients who can become pregnant should have a negative pregnancy test prior to treatment with ambrisentan tablets [see Dosage and Administration (2.2), Contraindications (4.1), Warnings and Precautions (5.1), Use in Specific Populations (8.1, 8.3)].

Counsel patients who can become pregnant about pregnancy planning and prevention, including emergency contraception, or designate counseling by another healthcare provider trained in contraceptive counseling [see Boxed Warning].

Hepatic Effects
Advise patients of the symptoms of potential liver injury and instruct them to report any of these symptoms to their physician.

Hematological Change
Advise patients of the importance of hemoglobin testing.

Other Risks Associated with Ambrisentan Tablets
Instruct patients that the risks associated with ambrisentan tablets also include the following:

• Decreases in sperm count
• Fluid overload

Administration
Advise patients not to split, crush, or chew tablets.

• have entered puberty, even if they have not started their menstrual period, and
• have a uterus, and
• have not gone through menopause. Menopause means that you have not had a menstrual period for at least 12 months for natural reasons, or that you have had your ovaries removed.

• have not yet entered puberty, or
• do not have a uterus, or
• have gone through menopause. Menopause means that you have not had a menstrual period for at least 12 months for natural reasons, or that you have had your ovaries removed, or
• who are infertile for any other medical reason and this infertility is permanent and cannot be reversed

If you are the parent or caregiver of a female child who started taking ambrisentan tablets before reaching puberty, you should check your child regularly to see if she is developing signs of puberty. Tell your doctor right away if you notice that she is developing breast buds or pubic hair. Your doctor should decide if your child has reached puberty. Your child may reach puberty before having her first menstrual period.

This Medication Guide has been approved by the U.S. Food and Drug Administration.

Distributed by:
Mylan Pharmaceuticals Inc., a Viatris Company
Morgantown, WV 26505 U.S.A.

Manufactured by:
Mylan Laboratories Limited
Hyderabad — 500 096, India

Revised: 12/2025
MX:AMBR:R7

NDC 0378-4270-93

Ambrisentan
Tablets
5 mg

PHARMACIST: Dispense the accompanying
Medication Guide to each patient.

Rx only
30 Tablets

Each film-coated tablet contains:
Ambrisentan      5 mg

Usual Dosage: See accompanying
prescribing information.

Do not split, crush or chew your tablets.

Keep this and all medication out of the
reach of children.

Store at 20° to 25°C (68° to 77°F). [See
USP Controlled Room Temperature.]

Distributed by:
Mylan Pharmaceuticals Inc.,
a Viatris Company
Morgantown, WV 26505 U.S.A.

Made in India

Viatris.com

RMX4270H2

Dispense only in original container.

Keep container tightly closed.

Code No.: MH/DRUGS/25/NKD/89

Ambrisentan Tablets 5 mg Bottle Label (Image 06)

NDC 0378-4271-93

Ambrisentan
Tablets
10 mg

PHARMACIST: Dispense the accompanying
Medication Guide to each patient.

Rx only
30 Tablets

Each film-coated tablet contains:
Ambrisentan      10 mg

Usual Dosage: See accompanying
prescribing information.

Do not split, crush or chew your tablets.

Keep this and all medication out of the
reach of children.

Store at 20° to 25°C (68° to 77°F). [See
USP Controlled Room Temperature.]

Distributed by:
Mylan Pharmaceuticals Inc.,
a Viatris Company
Morgantown, WV 26505 U.S.A.

Made in India

Viatris.com

RMX4271H2

Dispense only in original container.

Keep container tightly closed.

Code No.: MH/DRUGS/25/NKD/89

Ambrisentan Tablets 10 mg Bottle Label (Image 07)