DECAPEPTYL SR 22.5MG INJECTION

DECAPEPTYL SR contains triptorelin, a synthetic analogue of gonadotropin-releasing hormone (GnRH), also called luteinizing hormone-releasing hormone (LHRH). Unlike natural GnRH, which acts in pulses, continuous triptorelin administration suppresses the pituitary gland's production of LH and FSH, leading to a profound and reversible reduction in sex hormone levels (testosterone in men, estrogen in women).

DECAPEPTYL SR 22.5 mg is a long-acting depot formulation given as a single injection every 6 months.

It is used for:

·       advanced hormone-sensitive prostate cancer (androgen deprivation therapy)

·       endometriosis: to reduce ectopic endometrial tissue and relieve pain

·       uterine fibroids — preoperative treatment to reduce fibroid volume

·       precocious puberty (central) in children.

By maintaining castrate levels of testosterone (less than 50 ng/dL) in men with prostate cancer, DECAPEPTYL SR slows tumor growth and reduces disease burden, making it a cornerstone of hormonal treatment for this condition.

Assisted reproductive technology, controlled ovarian hyperstimulation, adjunctive therapy - SUBQ: Usual dose: 0.1 mg once daily initiated on day 2 or 3 or days 21 to 23 of menstrual cycle (or 5 to 7 days before expected onset of menses)

Breast cancer: IM: 3.75 mg once every 28 days ± 3 days (in combination with adjuvant endocrine therapy) for ~5 years; if receiving chemotherapy, begin ovarian suppression with the start of chemotherapy

Endometriosis - 3.75 mg once every 4 weeks for a total of 6 doses

must never be self-administered.

Administration

•       Reconstitute the powder with the provided diluent immediately before administration.

•       Inject the full suspension slowly as a deep intramuscular injection.

•       Rotate injection sites to minimize local reactions.

•       Appointments every 6 months must be kept consistently to maintain hormone suppression.

Testosterone Flare — First Injection

In the first 1–2 weeks of therapy, triptorelin initially stimulates LH/FSH release before causing suppression. This 'tumor flare' may temporarily worsen prostate cancer symptoms. In patients at risk of neurological complications (spinal cord compression), anti-androgens (e.g., bicalutamide) should be co-administered for the first 3–4 weeks of treatment.

Very Common Side Effects (more than 1 in 10 patients)

•       Hot flushes / hot flashes — due to oestrogen/testosterone suppression.

•       Decreased libido and sexual dysfunction (impotence in men).

•       Injection site reactions: pain, bruising, redness.

Common Side Effects

•       Fatigue and weight gain.

•       Mood changes, depression.

•       Bone pain (especially at the start of prostate cancer therapy — tumour flare).

•       Sweating.

Long-term Effects of Hormone Suppression

•       Osteoporosis and increased fracture risk with prolonged therapy — bone density monitoring is recommended.

•       Gynaecomastia (breast enlargement in men).

•       Metabolic changes: increased blood glucose, hyperlipidaemia (increased cardiovascular risk).

•       Muscle mass loss (sarcopenia).

Serious Side Effects — Seek Immediate Medical Attention

•       Spinal cord compression or urinary tract obstruction (initial flare in prostate cancer patients).

•       QT/QTc interval prolongation — risk of serious cardiac arrhythmia.

•       Pituitary apoplexy (rare) — sudden headache, visual changes, vomiting.

Tumour Flare Risk

In men with prostate cancer, the initial testosterone surge (flare) during the first 2 weeks can worsen symptoms. Patients with existing spinal metastases are at risk of spinal cord compression. Anti-androgen cover (e.g., bicalutamide 50 mg daily for 3–4 weeks) must be prescribed before or at the time of the first injection in high-risk patients.

Cardiovascular Risk

Androgen deprivation therapy increases cardiovascular risk including QT prolongation. Baseline ECG, electrolytes, and cardiovascular assessment should be performed before starting therapy and monitored during treatment. Correct electrolyte imbalances (hypokalaemia, hypomagnesaemia) before initiation.

Bone Density

Long-term androgen/oestrogen deprivation causes bone loss. Patients on prolonged therapy should receive calcium and vitamin D supplementation. DEXA scans to monitor bone mineral density should be considered at baseline and periodically.

Diabetes and Metabolic Effects

GnRH analogues can impair insulin sensitivity. Patients with diabetes require closer monitoring of blood glucose. Lipid profiles should be checked periodically.

Paediatric Use

For central precocious puberty, treatment must be initiated by a paediatric endocrinologist. After stopping treatment, normal pubertal development should resume. Monitor bone age during therapy.

Triptorelin has clinically significant interactions with several drug classes:

•       Drugs that prolong QT interval (antiarrhythmics, certain antipsychotics, antimalarials, methadone) — increased risk of serious arrhythmia; use with caution and with ECG monitoring.

•       Anti-androgens (bicalutamide, flutamide) — intentionally co-prescribed to prevent tumour flare at initiation; monitor for additive hepatotoxicity.

•       Hyperprolactinaemia-inducing drugs (antipsychotics, metoclopramide) — may blunt the GnRH agonist effect; avoid concurrent use.

•       Drugs that decrease bone density (corticosteroids, antiepileptics) — increased risk of osteoporosis; co-prescribe bone protection measures.

Store the DECAPEPTYL SR vial at room temperature, below 25 degrees Celsius. Do not refrigerate or freeze.

•       Keep in the original packaging to protect from light.

•       The reconstituted suspension must be used immediately — do not store.

•       Keep out of reach and sight of children.

•       Do not use after the expiry date printed on the pack.

Anti-androgen Cover Protocol

Prescribe bicalutamide 50 mg daily (or flutamide 250 mg three times daily) starting 3 days before the first triptorelin injection, continuing for at least 3 weeks post-injection, in patients with: PSA >20 ng/mL, locally advanced disease, bone metastases, or risk of spinal cord compression.

Monitoring Parameters

•       Serum testosterone: confirm castrate levels (<50 ng/dL) at 3 months, then every 6 months.

•       PSA: every 3–6 months in prostate cancer.

•       Bone density (DEXA): baseline and annually for long-term therapy.

•       Fasting glucose and HbA1c: baseline and 6-monthly in diabetic patients.

•       ECG: baseline; repeat if symptomatic or on QT-prolonging co-medications.

•       Serum electrolytes (K+, Mg2+): before initiation and periodically.

Reconstitution

Reconstitute using only the supplied solvent. Shake well until a uniform milky suspension is formed. Administer immediately. The 22.5 mg formulation uses microencapsulated microspheres — do not use needles smaller than 21G to avoid blockage.

Will this injection make me permanently unable to produce testosterone?

No. Testosterone suppression is reversible. After stopping treatment, testosterone levels gradually return to normal over several months. However, recovery time varies by individual and duration of therapy.

Why might my symptoms get worse at the beginning of treatment?

During the first 1–2 weeks, triptorelin temporarily stimulates hormone production before suppressing it. This 'flare effect' can worsen symptoms temporarily. Your doctor may prescribe an anti-androgen medicine to cover this period.