Drug acting on reproductive system Notes PDF

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Drugs Acting on the Reproductive System Notes: Downloadable PDF

Download comprehensive notes on drugs acting on the reproductive system in PDF format. These notes cover a wide range of medications that affect the male and female reproductive systems, including hormonal contraceptives (oral, injectable, transdermal, etc.), fertility drugs (clomiphene, gonadotropins), drugs for erectile dysfunction (sildenafil, tadalafil), androgens (testosterone), antiandrogens (finasteride, spironolactone), and others. Learn about their mechanisms of action, clinical uses, benefits, and potential side effects. Ideal for students, researchers, and healthcare professionals. Download now for convenient offline access.

Keywords: Reproductive System, Drugs, Medications, PDF, Download, Notes, Hormonal Contraceptives, Fertility Drugs, Erectile Dysfunction, Androgens, Antiandrogens, Estrogen, Progestin, Testosterone, Clomiphene, Gonadotropins, Sildenafil, Tadalafil, Vardenafil, Finasteride, Spironolactone, Flutamide, Cyproterone Acetate, Pharmacology, Mechanism of Action, Clinical Uses, Side Effects.

Drugs Acting on the Reproductive System: A Comprehensive Overview

The reproductive system is influenced by a complex interplay of hormones. Medications that act on the reproductive system can either mimic or block the effects of these hormones, or they can alter hormone synthesis or metabolism. This document provides an overview of major drug classes affecting the reproductive system.

I. Hormonal Contraceptives

Hormonal contraceptives are used to prevent pregnancy. They primarily contain synthetic versions of estrogen and/or progestin (a synthetic progestogen).

• Combined Hormonal Contraceptives (CHCs): Contain both estrogen (usually ethinyl estradiol) and a progestin.
  • Forms: Oral pills (combined oral contraceptives - COCs), transdermal patch, vaginal ring.
  • Mechanism of Action:
    • Prevent ovulation (primarily by suppressing the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland).
    • Thicken cervical mucus, making it difficult for sperm to enter the uterus.
    • Alter the endometrium (lining of the uterus), making it less receptive to implantation.
  • Examples: Many different combinations of estrogens and progestins are available.
  • Side effects: Nausea, headache and increase risk of thromboembolism.
• Progestin-Only Contraceptives:
  • Forms: Oral pills ("mini-pill"), injectable (depot medroxyprogesterone acetate - DMPA), intrauterine device (IUD) (levonorgestrel-releasing IUD), implant (etonogestrel).
  • Mechanism of Action:
    • Thicken cervical mucus (primary mechanism).
    • Alter the endometrium.
    • May inhibit ovulation (but less consistently than CHCs).
  • Examples: Norethindrone.
  • Side effects: Irregular bleeding.

II. Fertility Drugs

Fertility drugs are used to stimulate ovulation in women who are having difficulty conceiving.

• Clomiphene Citrate:
  • Mechanism of Action: A selective estrogen receptor modulator (SERM) that acts as an estrogen antagonist in the hypothalamus. This blocks the negative feedback of estrogen on the hypothalamus, leading to increased release of gonadotropin-releasing hormone (GnRH), which in turn stimulates the release of FSH and LH from the pituitary gland. FSH and LH stimulate follicle development and ovulation.
  • Clinical Uses: Ovulation induction in women with anovulation (lack of ovulation) or oligo-ovulation (infrequent ovulation), such as in polycystic ovary syndrome (PCOS).
  • Side effects: Hot flashes, multiple gestations.
• Gonadotropins:
  • Examples: Human menopausal gonadotropin (hMG) (contains FSH and LH), follicle-stimulating hormone (FSH) (urofollitropin, follitropin alfa, follitropin beta), human chorionic gonadotropin (hCG).
  • Mechanism of Action: Directly stimulate the ovaries to develop and mature follicles. hCG is used to trigger ovulation.
  • Clinical Uses: Ovulation induction in women who do not respond to clomiphene, assisted reproductive technologies (ART) (e.g., in vitro fertilization - IVF).
  • Side Effects: Ovarian hyperstimulation syndrome (OHSS) - a potentially serious complication, multiple gestations.
  • Administration: Injectable.
• GnRH Agonist and Antagonist: Used to control timing of ovulation.
• Letrozole: An aromatase inhibitor, also used for ovulation induction.
• Metformin: Used for PCOS.

III. Drugs for Erectile Dysfunction

Erectile dysfunction (ED) is the inability to achieve or maintain an erection sufficient for satisfactory sexual performance. The most commonly used drugs for ED are phosphodiesterase-5 (PDE5) inhibitors.

• PDE5 Inhibitors:
  • Examples: Sildenafil (Viagra), Tadalafil (Cialis), Vardenafil (Levitra), Avanafil (Stendra).
  • Mechanism of Action: Inhibit the enzyme phosphodiesterase-5 (PDE5), which normally breaks down cyclic GMP (cGMP) in the corpus cavernosum of the penis. cGMP is a vasodilator that promotes smooth muscle relaxation and increased blood flow, leading to an erection. By inhibiting PDE5, these drugs increase cGMP levels and enhance the erectile response to sexual stimulation. *They do not cause erections in the absence of sexual stimulation.*
  • Clinical Uses: Erectile dysfunction. Tadalafil is also approved for benign prostatic hyperplasia (BPH).
  • Side Effects: Headache, flushing, nasal congestion, visual disturbances (e.g., blue tinge to vision), back pain (tadalafil), dyspepsia. *Contraindicated with nitrates (can cause severe hypotension).*
• Alprostadil: Prostaglandin E1, can be injected into the penis.

IV. Androgens and Antiandrogens

• Androgens (e.g., Testosterone):
  • Mechanism of Action: Testosterone is the primary male sex hormone. It binds to androgen receptors, promoting the development and maintenance of male secondary sexual characteristics, spermatogenesis, and muscle growth.
  • Clinical Uses: Male hypogonadism (testosterone deficiency), delayed puberty in males, certain types of breast cancer (palliative treatment).
  • Forms: Injectable (testosterone enanthate, testosterone cypionate), transdermal patch, gel, buccal tablets, implantable pellets.
  • Side effects: Acne, male-pattern baldness.
• Antiandrogens: Block the effects of androgens.
  • 5α-Reductase Inhibitors:
    • Examples: Finasteride, Dutasteride.
    • Mechanism of Action: Inhibit the enzyme 5α-reductase, which converts testosterone to dihydrotestosterone (DHT). DHT is a more potent androgen that plays a key role in prostate growth and male pattern baldness.
    • Clinical Uses: Benign prostatic hyperplasia (BPH), male pattern baldness (finasteride).
    • Side effects: Decreased libido, erectile dysfunction.
  • Androgen Receptor Antagonists:
    • Examples: Flutamide, Bicalutamide, Enzalutamide, Apalutamide, Spironolactone.
    • Mechanism of Action: Block the binding of androgens (testosterone and DHT) to androgen receptors.
    • Clinical Uses: Prostate cancer (flutamide, bicalutamide, enzalutamide, apalutamide), hirsutism (excessive hair growth in women) (spironolactone), acne (spironolactone).

V. Other drugs

• Oxytocin and atosiban: Drugs for labour.
• Estrogen and progestin: For hormone replacement therapy.

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