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Transient changes in blood pressure, either increases or decreases, frequently occur immediately following administration of Thyrel TRH (protirelin) . Blood pressure should therefore be measured before Thyrel TRH (protirelin) is administered and at frequent intervals during the first 15 minutes after its administration.
Increases in systolic pressure (usually less than 30 mm Hg) and/or increases in diastolic pressure (usually less than 20 mm Hg) have been observed more frequently than decreases in pressure. These changes have not ordinarily persisted for more than 15 minutes nor have they required therapy. More severe degrees of hypertension or hypotension with or without syncope have been reported in a few patients. To minimize the incidence and/or severity of hypotension, the patient should be supine before, during, and after Thyrel TRH (protirelin) administration. If a clinically important change in blood pressure occurs, monitoring of blood pressure should be continued until it returns to baseline levels.
Thyrel TRH (protirelin) should not be administered to patients in whom marked, rapid changes in blood pressure would be dangerous unless the potential benefit clearly outweighs the potential risk.
Thyroid hormones reduce the TSH response to Thyrel® TRH (protirelin) . Accordingly, patients in whom Thyrel TRH (protirelin) is to be used diagnostically should be taken off liothyronine (T3) approximately seven days prior to testing and should be taken off thyroid medications containing levothyroxine (T4), e.g., desiccated thyroid, thyroglobulin, or liotrix, at least 14 days before testing. Hormone therapy is NOT to be discontinued when the test is used to evaluate the effectiveness of thyroid suppression with a particular dose of T4 in patients with nodular or diffuse goiter, or for adjustment of thyroid hormone dosage given to patients with primary hypothyroidism.
Chronic administration of levodopa has been reported to inhibit the TSH response to Thyrel TRH (protirelin) .
It is not advisable to withdraw maintenance doses of adrenocortical drugs used in the therapy of known hypopituitarism. Several published reports have shown that prolonged treatment with glucocorticoids at physiologic doses has no significant effect on the TSH response to thyrotropin releasing hormone, but that the administration of pharmacologic doses of steroids reduces the TSH response. Therapeutic doses of acetylsalicylic acid (2 to 3.6 g/day) have been reported to inhibit the TSH response to protirelin. The ingestion of acetylsalicylic acid caused the peak level of TSH to decrease approximately 30% as compared to values obtained without acetylsalicylic acid administration. In both cases, the TSH peak occurred 30 minutes post-administration of protirelin.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term animal studies have not been performed to evaluate the carcinogenic potential of protirelin. Studies to determine potential effects concerning mutagenesis or impairment of fertility have also not been performed.
Pregnancy (Category C)
Protirelin has been shown to increase the number of resorptions in rabbits, but not in rats, when given in doses 1 Â½ and 6 times the human dose. There are no adequate and well-controlled studies in pregnant women. Thyrel TRH (protirelin) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Thyrel® TRH (protirelin) is administered to a nursing woman.
Last reviewed on RxList: 1/18/2005
This monograph has been modified to include the generic and brand name in many instances.
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