Oral administration
The most frequently employed route for giving medication is by mouth. The drug is usually absorbed through the lining of the small bowel after passage through the stomach. The rate of gastric (stomach) emptying varies between individuals and this may explain some differences in drug response. Absorption of hormones may be reduced by chronic bowel conditions, such as coeliac disease, or an acute gastrointestinal illness involving vomiting and diarrhoea. This may result in unwanted pregnancy in women taking oral contraceptives, or irregular bleeding in women taking either the oral contraceptive pill or HRT. The circulation is such that blood from the small bowel travels directly to the liver. The liver may break down most of the drug on this ?first pass?.
Other routes are chosen for a variety of reasons including problems getting the drug safely through the acid milieu of the stomach and yet in a suitable state for absorption by the small bowel and also if the liver will let very little through during the first pass after absorption from the bowel.
Vaginal or rectal routes
Rectal or vaginal progesterone suppositories/pessaries have been frequently prescribed for patients with premenstrual syndrome (PMSprogesterone and progestogen in PMS), for infertility including IVF (24) and to try to reduce miscarriages for those with recurring problems (Q12.16). More recently a vaginal progesterone gel (Crinone Serono) has been marketed for infertility, PMS and in the management of the menopause. The vagina has been shown to be a useful route of administration of oestrogen in hormone replacement therapy (Menoring estradiol acetate Galen Ltd).
Some drugs that are usually taken by mouth, such as bromocriptine and cabergoline (Q6.21) may cause nausea or vomiting even when taken after meals, as they have a direct action on the stomach. The vagina may prove to be a useful alternative route.
Intramuscular and subcutaneous routes
Most drugs are water-soluble and they are readily absorbed by the small intestine, or they are lipid (fat) soluble. Lipid soluble drugs are absorbed when injected into a muscle (intramuscular) or into the fat under the skin (subcutaneous). A depot preparation of medroxyprogesterone acetate provides reliable contraception for three months (Depo-Provera). Diabetics have undertaken self-injection of insulin for many years. Patients are increasingly being taught to self-inject hormones for infertility treatment.
Implants of oestradiol and testosterone are inserted under the skin for some women requiring hormone replacement therapy (Q 28.5). Similarly, one GnRH agonist implant, goserelin (Zoladex -Zeneca) is introduced monthly for some patients with endometriosis (endometriosis) or with fibroids before surgery (17).
Transdermal route
There are a variety of patches favoured by some patients for their hormone replacement. Some contain oestradiol only (Table 28.2) while others have oestradiol combined with progestogen either cyclically or continuously.
Nasal route
Gonadotrophin-releasing hormone agonists, including nafarelin and buserelin, can be administered by nasal spray for treatment of endometriosis, pre-operative preparation for myomectomy (fibroid removal -17), preparation of the endometrium before endometrial ablation (endometrial ablation) and in some infertility regimens (24). A new HRT preparation (Aerodiol estradiol hemihydrate - Servier) is administered by nasal spray (Q 28.5).
Intrauterine route
The levonorgestrel intrauterine system (Mirena) is an intrauterine contraceptive device (IUCD) that releases the e quivalent of two progestogen only pills each week. It is licensed for contraception (Mirena) but it may also have a place in the management of dysfunctional uterine bleeding (heavy periods with no specific causeQ14.36). It provides not only contraception in pre-menopausal women but endometrial protection when oestrogen is administered either to control premenstrual (Q14.37) or menopausal symptoms (Q 28.15). A variety of other applications are under consideration including the management of endometriosis.
Please click on the required question.
- 1 What might I need to know about drugs frequently used in gynaecology?
- 2 How do hormone treatments work?
- 3 In what situations may hormone treatments be indicated?
- 4 What are the sources of hormone treatments?
- 5 What determines the effect of a hormone treatment?
- 6 When are hormones used in combination?
- 7 Why do hormone treatments sometimes cause side effects?
- 8 When are oestrogens prescribed?
- 9 What are the possible side effects and risks of oestrogen therapy?
- 10 When are progestogens prescribed?
- 11 What are the possible side effects and risks of progestogen therapy?
- 12 How is the relative potency (strength) of progestogens measured?
- 13 When is danazol prescribed?
- 14 When are androgens prescribed?
- 15 What are the possible side effects of androgens?
- 16 What are gonadotrophin releasing hormone analogues and gonadotrophins?
- 17 When are GnRH analogues prescribed?
- 18 What are anti-hormones?
- 19 By which routes can drugs be given and why are they chosen?
- 20 Why do I seem to be given a medication with a different name but my doctor says it is the same as before?
- 21 I am worried about the possible side effects of a medication. What should I do?
- 22 How are new treatments developed?
- 23 What is a meta-analysis?
- 24 What is meant by the term evidence based medicine information?
- 25 What is a clinical trial?
- 26 What is a placebo?
- 27 What is meant by relative risk?
- 28 What is informed consent?
- 29 What is the current opinion of the medical profession on alternative or complementary medicine?
- 30 Support Groups.
Thank you for choosing to visit us.
This is the personal website of David A Viniker MD FRCOG, Consultant Obstetrician and Gynaecologist at Whipps Cross University Hospital, London - Specialist Interests - Reproductive Medicine including Infertility, PCOS, PMS, Menopause and HRT.
I do hope that you find the answers to your women's health questions in the patient information and medical advice provided.
