norethisterone enantate: clinical use

Prescribing considerations

• Confirm that short-term injectable contraception matches the licensed indication and the patient’s preferences.
• Exclude pregnancy and assess personal and family history before treatment.
• Investigate unexplained uterine bleeding before use and consider ectopic pregnancy if suggestive pain and bleeding occur.
• Counsel about likely menstrual disturbance, lack of STI protection and potential mood effects.
• Use caution with previous ectopic pregnancy, a single fallopian tube, diabetes, previous liver dysfunction or severe depression.

Contraindications and cautions

• Known or suspected pregnancy
• Current or severe hepatic disease with abnormal liver function, or previous or current liver tumour
• Severe diabetes with vascular disease
• Pathologically raised blood pressure
• Current thromboembolic disease; previous thrombosis is an important product-specific precaution
• Disturbed lipid metabolism
• Suspected, current or treated breast or endometrial cancer
• Porphyria
• Hypersensitivity to norethisterone enantate or an excipient

Monitoring

• Record blood pressure and review relevant medical and family history before treatment and at clinically appropriate follow-up.
• Monitor diabetes control and reassess antidiabetic treatment if necessary.
• Assess new neurological, thrombotic, hepatic or severe depressive symptoms before considering further exposure.
• Exclude pregnancy before further administration when amenorrhoea creates uncertainty.

Clinical pharmacology

The oily intramuscular depot releases norethisterone enantate, which is hydrolysed to active norethisterone. Contraception results from ovulation suppression and effects on cervical mucus and endometrium. Some norethisterone is converted to ethinylestradiol, so systemic oestrogenic effects cannot be excluded.

Formulation and product differences

• The selected product is an oily solution for deep gluteal intramuscular injection supplied in a single glass ampoule.
• It contains castor oil and benzyl benzoate and must not be mixed with other medicines.
• The viscous injection must be administered very slowly by a healthcare professional; it is not a subcutaneous self-injection product.

Injection

Route: Parenteral

Strengths: 200 mg