Oestrogel

Indications

• Menopausal symptoms
• Osteoporosis prophylaxis
• Irregular menstruation
• Vulvovaginal atrophy
• Postmenopausal urogenital conditions

Dosage

Adults: The typical adult dosage of estradiol is 2 mg daily, initiated on day 1-5 of the menstrual cycle or at any time if cycles have ceased or are infrequent, taken with

Mechanism of action

Estradiol exerts its effects by binding to estrogen receptors, specifically estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), as well as the G protein-coupled estrogen receptor (GPER). This binding triggers the receptor-ligand complex to translocate to the nucleus, where it regulates gene transcription and the synthesis of specific proteins that mediate estradiol's physiological effects.

Pharmacodynamics

Estradiol acts on estrogen receptors to alleviate vasomotor symptoms such as hot flashes and urogenital symptoms including vaginal dryness. It has beneficial effects on bone density by inhibiting bone resorption and improving plasma lipid profiles. Additionally, estradiol decreases follicle-stimulating hormone (FSH) levels by suppressing its formation in the anterior pituitary gland. Notably, it may increase the risk of cardiovascular events, venous thromboembolism, and stroke, necessitating caution in high-risk populations.

Pharmacokinetics

Estradiol is rapidly absorbed when administered orally, with a bioavailability affected by first-pass metabolism in the liver. It is extensively metabolized in the liver, conjugated to form estrone and estrone sulfate, and eliminated through urine. The half-life of estradiol varies depending on the route of administration, with peak plasma concentrations occurring within 1-3 hours post-administration. Continuous use can lead to accumulation and requires careful monitoring of therapy duration and dosage adjustments.

Contra-indications

• History of thromboembolic disorders
• Known or suspected estrogen-dependent tumors
• Undiagnosed abnormal genital bleeding
• Severe liver dysfunction
• Pregnancy

Adverse effects

• Nausea
• Headaches
• Weight changes
• Breast tenderness
• Mood alterations
• Vaginal discharge
• Oedema
• Skin reactions
• Thromboembolic events
• Cerebrovascular accidents
• Endometrial hyperplasia
• Angioedema

Interactions

• Antiepileptics (carbamazepine, phenytoin, etc.) may decrease efficacy of estradiol
• Bosentan may decrease efficacy of estradiol
• Modafinil may decrease efficacy of estradiol
• Rifamycins may decrease efficacy of estradiol
• St. John's Wort may decrease efficacy of estradiol
• Ritonavir may decrease efficacy of estradiol

Precautions

• Monitor for signs of thromboembolic events
• Evaluate for endometrial hyperplasia in women with a uterus
• Consider cardiovascular risks before initiating therapy
• Assess liver function prior to use
• Use with caution in patients with a history of depression

Pregnancy

Estradiol is contraindicated in pregnancy due to potential harm to the fetus and increased risk of thromboembolic events.

Breast-feeding

Estradiol is excreted in breast milk; caution is advised when used by nursing mothers as it may affect milk production.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Tablets (1 mg, 2 mg)
• Vaginal ring (continuous use, replaced every 3 months)

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations.

Adults: Refer to the BNF for specific dosing recommendations.

Mechanism of action

The exact mechanism of action for Hemi is not explicitly detailed in the available resources, but compounds with similar structure may act by modulating neurotransmitter levels, inhibiting enzymes, or affecting cellular signaling pathways.

Pharmacodynamics

Hemi may exhibit pharmacodynamic properties that include modulation of neural activity or inhibition of specific biochemical pathways. Its effects could be dose-dependent and vary based on the therapeutic context.

Pharmacokinetics

The pharmacokinetic profile of Hemi, including absorption, distribution, metabolism, and excretion, is not well-documented in the provided resources. Generally, compounds in this class may undergo first-pass metabolism and have a variable half-life.

Dosage

Children: Refer to the specific formulation or active ingredient for dosing information.

Adults: Refer to the specific formulation or active ingredient for dosing information.

Mechanism of action

The mechanism of action of hemihydrate forms of drugs can vary widely depending on the specific compound. In many cases, the hemihydrate form enhances the solubility of the active ingredient, which facilitates its dissolution and absorption in the gastrointestinal tract.

Pharmacodynamics

Pharmacodynamics of hemihydrate compounds generally relates to the pharmacological effects that arise from the active drug once it is absorbed. The effects may vary based on the specific drug and its therapeutic target, but overall, the hemihydrate form aims to improve efficacy by ensuring adequate plasma concentrations are achieved more effectively than non-hydrated forms.

Pharmacokinetics

The pharmacokinetics of hemihydrate drugs typically demonstrate improved dissolution rates due to the presence of water, which can lead to increased absorption. This may result in quicker onset of action and modified half-lives. The specifics of absorption, distribution, metabolism, and excretion will depend on the active ingredient and its properties.

Pregnancy

Safety in pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether this drug is excreted in human milk. Caution should be exercised when administered to a nursing mother.

Storage

Store at room temperature, away from moisture and heat. Keep container tightly closed.

Mechanism of action

Estrogen is found in the the breast, uterine, ovarian, skin, prostate, bone, fat, and brain tissues. The main source of estrogen in adult women during the reproductive period of life is the ovarian follicle, which secretes 70 to 500 mcg of estradiol each day. After menopause, however, the majority of endogenous estrogen is produced by transformation of androstenedione (which is secreted by the adrenal cortex) to estrone in the peripheral tissues. Both estrone and its sulphate conjugated form, estrone sulphate, represent the most abundant estrogens found in postmenopausal women. Estradiol, however, is considerably more potent than estrone and estriol at the estrogen receptor (ER). As a result, the higher estrone concentration in postmenopausal population, can cause various undesirable effects. These effects may include hot flashes, chills, vaginal dryness, mood swings, irregular menstruation, and chills, in addition to sleep problems. Estradiol workings by binding to subtypes of the estrogen receptor: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). It also exerts potent agonism of G Protein-coupled estrogen receptor (GPER), which is recognized an important regulator of this drug's rapid effects. Once the estrogen receptor has bound to its ligand, it enters the nucleus of the target cell, regulating gene transcription and formation of of messenger RNA. This mRNA makes contact with ribosomes producing specific proteins that express the effect of estradiol upon the target cell. Agonism of estrogen receptors increases pro-estrogenic effects, leading to the relief of vasomotor and urogenital symptoms of a postmenopausal or low estradiol state. Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol at the receptor level. ... After menopause, most endogenous estrogen is produced by conversion of androstenedione, secreted by the adrenal cortex, to estrone by peripheral tissues. Thus, estrone and the sulfate conjugated form, estrone sulfate, are the most abundant circulating estrogens in postmenopausal women. Estrogens act through binding to nuclear receptors in estrogen-responsive tissues. To date, two estrogen receptors have been identified. These vary in proportion from tissue to tissue. Circulating estrogens modulate the pituitary secretion of the gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), through a negative feedback mechanism. Estrogens act to reduce the elevated levels of these hormones seen in postmenopausal women. Estrogens have an important role in the reproductive, skeletal, cardiovascular, and central nervous systems in women, and act principally by regulating gene expression. Biologic response is initiated when estrogen binds to a ligand-binding domain of the estrogen receptor resulting in a conformational change that leads to gene transcription through specific estrogen response elements (ERE) of target gene promoters; subsequent activation or repression of the target gene is mediated through 2 distinct transactivation domains (ie, AF-1 and AF-2) of the receptor. The estrogen receptor also mediates gene transcription using different response elements (ie, AP-1) and other signal pathways. Recent advances in the molecular pharmacology of estrogen and estrogen receptors have resulted in the development of selective estrogen receptor modulators (eg, clomiphene, raloxifene, tamoxifen, toremifene), agents that bind and activate the estrogen receptor but that exhibit tissue-specific effects distinct from estrogen. Tissue-specific estrogen-agonist or -antagonist activity of these drugs appears to be related to structural differences in their estrogen receptor

Pharmacodynamics

Estradiol acts on the on the estrogen receptors to relieve vasomotor systems (such as hot flashes) and urogenital symptoms (such as vaginal dryness and dyspareunia). Estradiol has also been shown to exert favorable effects on bone density by inhibiting bone resorption. Estrogen appears to inhibit bone resorption and may have beneficial effects on the plasma lipid profile. Estrogens cause an increase in hepatic synthesis of various proteins, which include sex hormone binding globulin (SHBG), and thyroid-binding globulin (TBG). Estrogens are known to suppress the formation of follicle-stimulating hormone (FSH) in the anterior pituitary gland. **A note on hyper-coagulable state, cardiovascular health, and blood pressure** Estradiol may cause an increased risk of cardiovascular disease, DVT, and stroke, and its use should be avoided in patients at high risk of these conditions. Estrogen induces a hyper-coagulable state, which is also associated with both estrogen-containing oral contraceptive (OC) use and pregnancy. Although estrogen causes an increase in levels of plasma renin and angiotensin. Estrogen-induced increases in angiotensin, causing sodium retention, which is likely to be the mechanism causing hypertension after oral contraceptive treatment.