Land: Sør-Afrika
Språk: engelsk
Kilde: South African Health Products Regulatory Authority (SAHPRA)
Schering
PRIMOLUT N SCHEDULING STATUS: S4 PROPRIETARY NAME (and dosage form): PRIMOLUT N Tablets COMPOSITION 1 tablet contains norethisterone (17-hydroxy-19-nor-17alpha-pregn-4-en-20-yn-3-one) 5,0 mg. PHARMACOLOGICAL CLASSIFICATION A. 21.8.2 Progesterones without estrogens. PHARMACOLOGICAL ACTION Pharmacodynamic properties Complete transformation of the endometrium can be achieved with 80 to 150 mg norethisterone, spread over 8 to 10 days, in adequately estrogen-primed castrated women. This amount is sufficient to bring the endometrium up to the condition which it is normally in at the end of the luteal phase. The menstruation-like withdrawal bleeding begins almost invariably 2 to 4 days after discontinuation of the medication. Norethisterone has an inhibitory effect on the secretion of gonadotropins in the anterior lobe of the pituitary. Norethisterone increases the basal body temperature: 10 mg norethisterone daily increases it by about 0,5°C. In addition to the transformatory action norethisterone also has a styptic effect. A local influence on the endometrium leads to the cessation of dysfunctional bleeding. Pharmacokinetic properties Absorption Orally administered norethisterone is absorbed over a wide dose range. Peak serum concentrations of about 16 ng/mL are reached within about 1,5 hours of administration of one 5 mg tablet Primolut N. Due to a marked first-pass effect, the bioavailability of norethisterone after an oral dose is about 64%. Distribution Norethisterone is bound to serum albumin and to sex hormone binding globulin (SHBG). Only about 3 to 4% of the total serum drug concentration is present as free steroid, about 35% and 61% is bound to SHBG and albumin, respectively. The apparent volume of distribution of norethisterone is 4,4 +1,3 L/kg. Following oral administration, t Les hele dokumentet