July 29, 2016
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Side Effects


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

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in 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 clinical practice.

Safety data for OPSUMIT were obtained primarily from one placebo-controlled clinical study in 742 patients with PAH (SERAPHIN study) [see Clinical Studies]. The exposure to OPSUMIT in this trial was up to 3.6 years with a median exposure of about 2 years (N=542 for 1 year; N=429 for 2 years; and N=98 for more than 3 years). The overall incidence of treatment discontinuations because of adverse events was similar across OPSUMIT 10 mg and placebo treatment groups (approximately 11%).

Table 2 presents adverse reactions more frequent on OPSUMIT than on placebo by ≥ 3%.

Table 2 : Adverse Reactions

Adverse Reaction OPSUMIT 10 mg
(N=242) (%)
(N=249) (%)
Anemia 13 3
Nasopharyngitis/pharyngitis 20 13
Bronchitis 12 6
Headache 14 9
Influenza 6 2
Urinary tract infection 9 6

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of OPSUMIT. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Immune system disorders: hypersensitivity reactions (angioedema, pruritus and rash)

Respiratory, thoracic and mediastinal disorders: nasal congestion

General disorders and administration site conditions: edema/fluid retention. Cases of edema and fluid retention occurred within weeks of starting Opsumit, some requiring intervention with a diuretic, fluid management or hospitalization for decompensated heart failure.

Cardiac disorders: symptomatic hypotension

Read the Opsumit (macitentan tablets) Side Effects Center for a complete guide to possible side effects


Strong CYP3A4 Inducers

Strong inducers of CYP3A4 such as rifampin significantly reduce macitentan exposure. Concomitant use of OPSUMIT with strong CYP3A4 inducers should be avoided [see CLINICAL PHARMACOLOGY].

Strong CYP3A4 Inhibitors

Concomitant use of strong CYP3A4 inhibitors like ketoconazole approximately double macitentan exposure. Many HIV drugs like ritonavir are strong inhibitors of CYP3A4. Avoid concomitant use of OPSUMIT with strong CYP3A4 inhibitors [see CLINICAL PHARMACOLOGY]. Use other PAH treatment options when strong CYP3A4 inhibitors are needed as part of HIV treatment [see CLINICAL PHARMACOLOGY].

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 7/1/2016

Side Effects

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