macitentan

(ma-si-ten-tan ) macitentan,

Opsumit

(trade name)

Classification

Therapeutic: temporary class
Pharmacologic: endothelin receptor antagonists
Pregnancy Category: X

Indications

Treatment of Pulmonary Hypertension (PAH, WHO Group I) to delay disease progression.

Action

Acts as an endothelin receptor antagonist. Endothelin mediates vasocontriction, fibrosis, proliferation, hypertrophy and inflammation. Antagonizing endothelin effects delays vascular hypertrophy and organ damage.

Therapeutic effects

Delayed sequelae of progression of PAH (death, need for initiation of parenteral prostanoids, increased frequency of hospitalization, diminished exercise tolerance or need for other interventions)

Pharmacokinetics

Absorption: Absorption follows oral administration, bioavailability Unknown.Distribution: Unknown.Protein Binding: Macitentan—>99%; active metabolite—>99%Metabolism and Excretion: Extensively metabolized, primarily by the CYP3A4 enzyme system with conversion to a pharmacologically active metabolite that contributes 40% of activity. 50% excreted in urine as metabolites, 24% in feces.Half-life: Macitentan—16 hr; active metabolite—48 hr

Time/action profile (improvement in primary endpoints†)

ROUTE	ONSET	PEAK	DURATION
PO	within 6 mos	12–18 mos	unknown

†worsening of PAH, death, or need for other interventions

Contraindications/Precautions

Contraindicated in: Strong inhibitors or inducers of the CYP3A4 enzyme system (can significantly alter drug effectiveness/risk of toxicity) Obstetric: Causes fetal harm, should not be used during pregnancy; Lactation: Discontinue drug or breast feedingUse Cautiously in: Females with reproductive potential (pregnancy must be excluded prior to treatment and for one mo following treatment, effective contraception must be utilized)Pulmonary veno-occlusive disease (↑ risk of pulmonary edema) Pediatric: Safe and effective use in children has not been established.

Adverse Reactions/Side Effects

Central nervous system

headache (most frequent)

Respiratory

pulmonary edema

Gastrointestinal

hepatotoxicity

Genitourinary

↓ sperm count

Hematologic

anemia (most frequent)

Interactions

Drug-Drug interaction

Strong CYP3A4 inducers including rifampin ↓ blood levels and effectiveness and should be avoided Strong CYP3A4 inhibitors including ketoconazole ↑ blood levels and risk of toxicity and should be avoided

Route/Dosage

Oral (Adults) 10 mg once daily

Availability

Tablets: 10 mg

Nursing implications

Nursing assessment

Monitor hemodynamic parameters and exercise tolerance prior to and periodically during therapy.
Assess for signs and symptoms of pulmonary edema (shortness of breath). If confirmed, discontinue therapy.
Lab Test Considerations: Obtain a negative pregnancy test prior to beginning, monthly during therapy, and 1 mo following treatment.
- Monitor hepatic function periodically during therapy. May cause ↑ AST, ALT, and bilirubin. If clinically relevant ↑ of AST or ALT occur, or if ↑ are accompanied by ↑ bilirubin >2 x upper limit of normal, or by clinical symptoms of hepatotoxicity, discontinue therapy. May re initiate therapy when hepatic enzyme levels normalize in patients who have not experienced clinical symptoms of hepatotoxicity.
- Monitor CBC before starting and periodically during therapy. May cause ↓ hemoglobin. Avoid therapy in patients with severe anemia.

Potential Nursing Diagnoses

Activity intolerance (Indications)

Implementation

Only available through a restricted program, Opsumit Risk Evaluation and Mitigation Strategy (REMS). Prescribers and pharmacies must be enrolled and certified. All female patients must enroll and comply with pregnancy testing and contraception requirements. Male patients do not need to enroll.
Oral: Administer once daily at the same time each day. Swallow tablets whole, do not break, crush, or chew.

Patient/Family Teaching

Instruct patient to take macitentan as directed. Take missed doses as soon as remembered unless almost time for next dose; do not double doses.
Advise patients to notify health care professional if symptoms of hepatic injury (nausea, vomiting, right upper quadrant pain, fatigue, anorexia, jaundice, dark urine, fever, itching) occur.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
Caution female patients that macitentan may harm fetus. Instruct females to use effective contraception (intrauterine device IUD, contraceptive implants, tubal sterilization) or a combination of methods (hormone method with a barrier method or two barrier methods) during and for at least a mo following discontinuation of therapy. If a partner’s vasectomy is method of contraception, a hormone or barrier method must be used along with this method. Counsel patient on emergency contraception. May decrease sperm count in male patients. Advise female patient to notify health care professional immediately if pregnancy is suspected and avoid breastfeeding.

Evaluation/Desired Outcomes

Increased exercise tolerance.