The intranasal route of estrogen administration provides a new, unique pharmacokinetic profile: “pulsating”. It is characterized by the maximum plasma concentration of estradiol which is attained rapidly, which then also quickly returns to its original level. The intranasal route of administration of hormones avoids the effect of primary passage through the liver, which leads to the appearance of a physiological correlation in blood between estradiol and estrone (0.8-1.1), which, moreover, does not depend on the dose taken. Systemic exposure to 300 µg of intranasal estradiol is equivalent to 50 µg of the transdermal patch or 2 mg of oral estradiol. As can be seen, the effect of intranasal use of estrogen is similar to sublingual.
There are no registered estrogen preparations for intranasal use in Russia.
Many patients with transsexualism prefer injectable forms of estrogen, however, the use of these drugs is undesirable due to the possibility of creating a high circulating level of androgens and an increased risk of overdose.
Prolonged drugs are dangerous because in the event of an emergency situation that may require urgent cancellation of estrogen therapy, it is impossible to cancel the effect of depot drugs.
Data on the use of these forms of drugs in transsexuals do not. The undesirability of their use for the treatment of patients with transsexualism is due to the same considerations as when using injection forms. In the study of therapy with estrogen implants in women received very good results. Thus, the subcutaneous implant 17-B-estradiol has established itself as a highly effective, easy-to-use treatment method that normalizes metabolic changes in young women with estrogen deficiency. Also, data were obtained on the advantages of using implantable forms of estrogen compared with oral administration in relation to the lipid profile, the level of lipoproteins, glucose and insulin.
Given the accumulated knowledge of some differences in the physiological effects of estrogens with different ways of their use, the approach to estrogen replacement therapy can be individualized. For example, oral medication may be more preferable in patients with hypercholesterolemia or in lowering HDL levels. Parenteral administration of estrogen is advisable in smoking patients with hypertriglyceridemia or cholelithiasis, with a tendency to thromboembolism. Some researchers strongly recommend switching from any form of estrogen therapy to transdermal after the patient reaches 40 years of age due to the increased incidence of thromboembolism in M / F-transsexuals of older age.