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Biomedical subjects

F Helmerhorst

Publications and source records attributed to F Helmerhorst.

6 recordsLinked to original sources
PubMed2001

Biphasic versus monophasic oral contraceptives for contraception.

OBJECTIVES: To compare biphasic oral contraceptives with monophasic oral contraceptives in terms of efficacy, cycle control, and discontinuation due to side effects. Our a priori hypotheses were: (a) biphasic oral contraceptives are less effective in preventing pregnancy than are monophasic oral contraceptives, and (b) biphasic oral contraceptives cause more side effects, give poorer cycle control, and have lower continuation rates. SEARCH STRATEGY: We searched computerized databases MEDLINE, EMBASE, Popline and the Cochrane Controlled Trial Register. Additionally we searched the reference lists of all potentially relevant articles and book chapters. We also contacted the authors of relevant studies and pharmaceutical companies in Europe and the U.S. SELECTION CRITERIA: We included randomized controlled trials comparing any biphasic oral contraceptive with any monophasic oral contraceptive when used to prevent pregnancy. DATA COLLECTION AND ANALYSIS: We examined the studies found during the various literature searches for possible inclusion and assessed their methodological quality using the Cochrane guidelines. We contacted the authors of all included studies and of possibly randomized studies for supplemental information about the study methods and outcomes. We entered the data in RevMan 3.1, imported the data into RevMan 4.1, and calculated Peto odds ratios for the incidence of intermenstrual bleeding, absence of withdrawal bleeding, and study discontinuation due to intermenstrual bleeding. MAIN RESULTS: Only one trial of limited quality compared a biphasic and monophasic preparation. Percival-Smith et al. (1990) examined 533 user cycles of a biphasic pill (norethindrone 500 mcg/ethinyl estradiol 35 mcg for ten days, followed by norethindrone 1000 mcg/ethinyl estradiol 35 mcg for eleven days; Ortho 10/11) and 481 user cycles of a monophasic contraceptive pill (norethindrone acetate 1500 mcg/ethinyl estradiol 30 mcg daily; Loestrin). The study found no significant differences in intermenstrual bleeding, amenorrhea and study discontinuation due to intermenstrual bleeding between the biphasic and monophasic oral contraceptive pills. REVIEWER'S CONCLUSIONS: Conclusions are limited by the identification of only one trial, the methodological shortcomings of that trial, and the absence of data on accidental pregnancies. However, the trial found no important differences in bleeding patterns between the biphasic and monophasic preparations studied. Since no clear rationale exists for biphasic pills and since extensive evidence is available for monophasic pills, the latter are preferred.

Contraception↗
PubMed2000

A switch from oral (2 mg/day) to transdermal (50 microg/day) 17beta-estradiol therapy increases serum insulin-like growth factor-I levels in recombinant human growth hormone (GH)-substituted women with GH deficiency.

The response to GH therapy in adults with GH deficiency (GHD) is considerably variable. Generally, the response with regard to serum insulin-like growth factor (IGF)-I concentrations is significantly lower in females compared with males with GHD, which could at least partly be explained by the use of oral estrogen replacement therapy. In the present study, we investigated whether a switch from oral to transdermal estrogen therapy alters serum IGF-I concentrations in women with GHD on stable GH therapy. Six females with GHD and LH deficiency were investigated. During cycles 1 and 2, an oral dose of estradiol was given (2 mg/day), whereas during cycles 3, 4, and 5 estradiol was administered via the transdermal route at a dose of 50 microg/day. Serum estrone levels significantly decreased (2470+/-475 to 110+/-26 pmol/L, P = 0.005), serum sex hormone-binding globulin levels significantly decreased (102+/-13 to 63+/-7 nmol/L, P = 0.004), and serum estradiol levels also decreased albeit nonsignificantly with transdermal therapy (273+/-81 to 114+/-18, P = 0.083). Serum IGF-I levels significantly increased after the switch from oral to transdermal estrogen therapy (18.7+/-1.6 and 23.4+/-2.5 nmol/L, respectively, P = 0.008). Two of the six patients experienced fluid retention-related side effects, which disappeared after a reduction in dose at the end of the study. The results of the present study suggest that the potency of GH is altered in patients on transdermal compared to oral estradiol therapy. Further investigation should be undertaken to answer the question whether the increase in serum IGF-I levels is due to lower serum levels of estradiol or to differences in the mode of administration of estradiol.

Administration, Cutaneous↗
PubMed1995

The influence of ovarian steroids on hypothalamic-pituitary-adrenal regulation in the female rat.

The present study examined the association between hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-ovarian axes. HPA activity determined by plasma levels of adrenocorticotropin (ACTH) and corticosterone (B) was assessed in intact female rats as a function of oestrous cycle stage under resting conditions and after exposure to a 20 min restraint stress. To delineate the roles of oestradiol and progesterone in HPA axis modulation, plasma concentrations of ACTH and B were determined in ovariectomised (OVX) animals treated with oestradiol and/or progesterone under resting conditions and during exposure to the stress of a novel environment. The effects of these steroid treatments on the transcription and/or binding properties of the two corticosteroid receptors, the mineralocorticoid (MR) and glucocorticoid (GR) receptors, were also examined in hippocampal tissue, (i) Fluctuations in basal and stress-induced plasma ACTH and B concentrations were found during the oestrous cycle with highest levels at late pro-oestrus. (ii) In OVX steroid-replaced animals, basal and stress-induced activity was enhanced in oestradiol and oestradiol plus progesterone-treated animals compared with OVX controls. (iii) Cytosol binding assays revealed an oestradiol-induced decrease in hippocampal MR capacity. This decrease appears to be due to an effect of the steroid on MR transcription as in situ hybridisation analysis of MR mRNA showed an oestradiol-induced decrease in MR transcript in all hippocampal subfields. (iv) Treatment of oestradiol-primed animals with progesterone reversed the oestradiol-induced decrease in hippocampal MR capacity. Data from MR mRNA hybridisation in situ experiments indicate that this reversal may be due to an antagonism of the oestradiol effect on MR transcription. (v) Progesterone treatment with or without prior oestradiol-priming induced a significant decrease in the apparent binding affinity of hippocampal MR. We show that progesterone and its 11 beta-hydroxylated derivative have a high affinity for the hippocampal MR. (vi) Neither oestradiol nor progesterone affected GR binding parameters in the hippocampus. In conclusion, we find that sex steroids modulate HPA activity and suggest that the observed effects of these steroids on hippocampal MR may underlie their concerted mechanism of action in inducing an enhanced activity at the period of late pro-oestrus.

Adrenocorticotropic Hormone↗