1. Clinical Overview
Triptorelin is a synthetic decapeptide analogue of Gonadotropin-Releasing Hormone (GnRH). The 0.1mg daily dose formulation is a short-acting agonist used primarily for the treatment of central precocious puberty (CPP) in children. It acts as a potent stimulator of pituitary gonadotropin secretion, leading to an initial surge (flare-up) in luteinizing hormone (LH) and follicle-stimulating hormone (FSH), followed by profound down-regulation and desensitization of GnRH receptors, resulting in sustained suppression of the gonadal axis.
| Onset | Duration | Bioavailability |
|---|---|---|
| Initial gonadotropin surge occurs within 30-60 minutes of administration. Clinical suppression of the gonadal axis (reduction in sex steroid levels) is typically observed within 2-4 weeks of continuous daily therapy. | The pharmacological effect is short-lived, requiring daily subcutaneous administration to maintain suppression. Gonadotropin and sex steroid levels begin to return to baseline within 24-72 hours after discontinuation. | Approximately 53-80% after subcutaneous injection. |
2. Mechanism of Action
Triptorelin is a superagonist analogue of endogenous GnRH. It binds with high affinity to GnRH receptors on anterior pituitary gonadotroph cells. Continuous daily administration leads to an initial, transient stimulation (flare) of LH and FSH release, followed by receptor desensitization and down-regulation. This results in a profound suppression of the pituitary-gonadal axis, leading to markedly reduced secretion of gonadal steroids (testosterone, estradiol). In CPP, this halts and reverses the progression of puberty.
3. Indications & Uses
- Central Precocious Puberty (CPP) in children (male and female) aged 2 years and above
4. Dosage & Administration
Adult Dosage: Not indicated for adults at 0.1mg strength. Adults use depot formulations (3.75mg, 11.25mg, 22.5mg).
Administration: For subcutaneous injection only. Rotate injection sites daily (abdomen, thigh, upper arm). Use a fine-gauge needle (e.g., 27-30G). Reconstitute immediately before use if using lyophilized powder with provided solvent. Administer at approximately the same time each day. Patient/parent must be trained in proper aseptic injection technique.
5. Side Effects
Common side effects may include:
- Injection site reactions (pain, erythema, itching, swelling)
- Initial pubertal flare symptoms (vaginal spotting/bleeding, breast tenderness, emotional lability in first 1-2 weeks)
- Headache
- Hot flushes/sweating
- Weight change
- Mild nausea
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Corticosteroids (e.g., Prednisolone) | May antagonize the suppressive effect of triptorelin on the pituitary-gonadal axis. | Moderate |
| Other sex hormones (Androgens, Estrogens, Progestins) | May interfere with the therapeutic effect of triptorelin. Concurrent use is contraindicated in CPP. | Major |
| Drugs that prolong QT interval (e.g., certain antipsychotics, antiarrhythmics) | Additive risk of QT prolongation; monitor ECG. | Moderate |
| Digoxin | Triptorelin may increase serum digoxin concentrations; monitor digoxin levels. | Moderate |
7. Patient Counselling
- DO administer the injection at the same time each day to maintain consistent suppression.
- DO rotate injection sites to prevent lipoatrophy or skin reactions.
- DO learn and maintain strict aseptic injection technique.
- DO keep regular appointments for monitoring growth, bone age, and hormone levels.
- DONT stop the medication abruptly without consulting the endocrinologist.
- DONT use if the solution is discolored or contains particles.
- DONT share needles or injection devices.
8. Toxicology & Storage
Overdose: Expected to be an extension of pharmacological effects: severe hypoestrogenism/hypogonadism symptoms (intense hot flushes, vaginal dryness, profound fatigue, mood depression). Acute overdose may cause nausea, abdominal discomfort, and headache.
Storage: Store unopened vials/pens in a refrigerator between 2°C and 8°C. Do not freeze. Protect from light. After reconstitution (if applicable), use immediately. For pre-filled syringes or pens, they may be kept at room temperature (not above 25°C) for a limited period (e.g., 7 days) as per manufacturer's instructions. Keep out of reach of children.