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Factrel (gonadorelin) as a single injection is indicated for evaluating the functional capacity and response of the gonadotropes of the anterior pituitary. This single-injection test does not measure pituitary gonadotropic reserve, for which more prolonged or repeated administration may be required. The LH response is useful in testing patients with suspected gonadotropin deficiency, whether due to the hypothalamus alone or in combination with anterior pituitary failure. Factrel (gonadorelin) is also indicated for evaluating residual gonadotropic function of the pituitary following removal of a pituitary tumor by surgery and/or irradiation. In clinical studies to date, however, the single-injection test has not been useful in differentiating pituitary disorders from hypothalamic disorders. The Factrel (gonadorelin) test can be performed concomitantly with other post-treatment evaluations. The results of the Factrel (gonadorelin) test complement the clinical examination and other laboratory tests used to confirm or substantiate hypogonadotropic hypogonadism.
In cases where there is a normal response, it indicates the presence of functional pituitary gonadotropes. The single-injection test does not measure pituitary gonadotropic reserve.
DOSAGE AND ADMINISTRATION
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Adults: 100 mcg dose, subcutaneously or intravenously. In females for whom the phase of the menstrual cycle can be established, the test should be performed in the early follicular phase (Days 1-7).
To determine the status of the gonadotropin secretory capacity of the anterior pituitary, a test procedure requiring seven venous blood samples for LH is recommended.
- Venous blood samples should be drawn at -15 minutes and immediately prior to Factrel (gonadorelin) administration. The LH baseline is obtained by averaging the LH values of the two samples.
- Administer a bolus of 100 mcg of Factrel (gonadorelin) subcutaneously or intravenously.
- Draw venous blood samples at 15, 30, 45, 60, and 120 minutes after administration.
- Blood samples should be handled as recommended by the laboratory that will determine the LH content. It must be emphasized that the reliability of the test is directly related to the inter-assay and intra-assay reliability of the laboratory performing the assay.
INTERPRETATION OF TEST RESULTS
Interpretation of the LH response to Factrel (gonadorelin) requires an understanding of the hypothalamic-pituitary physiology, knowledge of the clinical status of the individual patient, and familiarity with the normal ranges and the standards used in the laboratory performing the LH assays.
The Factrel (gonadorelin) test complements the clinical assessment of patients with a variety of endocrine disorders involving the hypothalamic-pituitary axis. In cases where there is a normal response, it indicates the presence of functional pituitary gonadotropes. The single-injection test does not determine the pathophysiological cause for the subnormal response and does not measure pituitary gonadotropic reserve.
Lyophilized Powder in single-dose Secule® vials containing 100 mcg (NDC 0046-0507-05) and 500 mcg (NDC 0046-0509-05) gonadorelin as the hydrochloride with 100 mg lactose, USP. Each Secule vial is accompanied by one ampul containing 2 mL sterile diluent of 2% benzyl alcohol in sterile water.
Store at room temperature (approximately 25°C).
Reconstitute 100 mcg Secule® vial with 1.0 mL of the accompanying sterile diluent.
Reconstitute 500 mcg Secule® vial with 2.0 mL of the accompanying sterile diluent.
Prepare solution immediately before use. After reconstitution, store at room temperature and use within 1 day.
Discard unused reconstituted solution and diluent.
Secule® Registered trademark to designate a vial containing an injectable preparation in dry form.
Ayerst Laboratories Inc.
A Wyeth-Ayerst Company
Philadelphia, PA 19101 This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 12/8/2004
Additional Factrel Information
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