English: Levels of estradiol and estrone (pg/mL), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (IU/L), and prolactin (ng/mL) following a single intramuscular injection of 5 mg estradiol valerate in an oil solution (1 ampoule of Estradiol Depot 5 mg by Jenapharm) in 17 postmenopausal women. The injections were given at t = 4 hours. Assays were performed using enzyme immunoassay. Estrone levels were likely overestimated, possibly due to cross reactivity of the assay with estrone conjugates such as estrone sulfate, according to Schug et al. (2012).

Source of the values:

• (2002). "Pharmakokinetik von Estron, Estradiol, FSH, LH und Prolaktin nach intramuskulärer Applikation von 5 mg Estradiolvalerat". Journal für Menopause 9 (2): 51–55.

Source of the commentary (on estrone levels):

• (February 2012). "Bioavailability and pharmacodynamics of two 10-mg estradiol valerate depot formulations following IM single dose administration in healthy postmenopausal volunteers". Int J Clin Pharmacol Ther 50 (2): 100–17. DOI:10.5414/CP201589. PMID 22257576.

Specific excerpt (from Schug et al. (2012) on estrone levels):

In another earlier study with only sparse measurements performed by Göretzlehner et al. [21] after i.m. administration of 5-mg E2V to 17 postmenopausal wome, the highest mean concentrations were observed on Day 5, amounting to 272 pg/ml for E2 and 447 pg/ml for E1 and resulting in an E1/E2 ratio of 1.65. Such a finding is in contrast to other data in literature and to the present study, at which E1/E2 ratios of 0.38 for test and reference products were calculated. E1/E2 ratios above 1 are well known for oral administration of E2V due to a pronounced first pass effect, thus such a metabolic ratio is mechanistically implausible after i.m. administration. It is difficult to judge what might be the reason for this observation as information about population characteristics is sparse. These authors used enzyme immunoassays for E2 and E1 determination, while a GC/MS-NCI-SIM method was used in the present study. Thus, the most probable explanation is that the lesser selectivity of the assay might have resulted in an overestimation of E1 concentrations. This assumption is supported by the fact that using the data from Düsterberg et al. [8], high E1/E2 ratios for C_max and AUC could be calculated when conjugated E1 (and not free E1) concentrations were considered. The aforementioned factors may at least partially explain the differences in the metabolic ratios observed in these two studies. Furthermore, the mean age of postmenopausal women in the present study was 13 years lower, but the measured baseline E2 and E1 concentrations were always significantly lower.