Hormonal Contraceptives - Video 1 Notes

Speaker background and scope

The transcript is the first of two videos on hormonal contraceptives. The presenter is Hilary Lloyd, affiliated with the Sydney School of Pharmacy Pharmacology. The speaker describes personal qualifications (physiology, pharmacology; PhD in neurochemistry) and traces career steps through postdoctoral positions in London, Dusseldor, Stockholm, and Sydney, culminating in a position at the University of Sydney since 1993. A note on terminology follows: the focus is on combined oral contraceptives (COCs) and progestogen-only pills (POPs), but orally administered contraceptives also include the combined hormonal patch and the combined vaginal ring; progestogen-only methods include implants, IUDs, and injectable/intramuscular or subcutaneous medroxyprogesterone. The speaker uses the term "progestogen" (Australia/UK usage) rather than "progestin" (US usage), though the meaning is the same. The transcript also frames a set of guiding questions about the pill as a symbol of liberation and notes evolving perspectives that some women reject hormonal contraception.

Nomenclature and scope of hormonal contraceptives

Key terms and scope covered:

Combined oral contraceptives (COCs) contain estrogens and progestogens.
Progestogen-only contraceptives include implants, IUDs, and injectable forms like medroxyprogesterone acetate.
In Australia/UK, the term "progestogen" is preferred; in the US, the term "progestin" is commonly used.
The presentation distinguishes between combined products and progestogen-only products, and notes that non-oral forms (patch, vaginal ring, implants, IUDs, injections) are increasingly used.

The historical question: the little pill that changed the world

Two questions are introduced for discussion in the second video: whether the contraceptive pill is an emblem of liberation, and how views on hormonal contraception have evolved. The speaker notes that Australia was the second country to make the pill available in 1960. However, views have shifted, with some women now challenging or rejecting hormonal contraception. These gray questions are highlighted as topics to be addressed in the second video.

Endogenous hormones: estrogens and progestogens

Endogenous hormones relevant to contraception:

The main estrogens: estradiol, estrone, and estriol.
The endogenous progestogen: progesterone.
Both estrogens and progestogens are steroid hormones derived from cholesterol, primarily synthesized in the ovaries, with smaller production in the adrenal cortex and placenta.
A simplified biosynthetic pathway is described:
$ext{Cholesterol} <br>ightarrow ext{Progesterone} <br>ightarrow ext{Androgens} <br>ightarrow ext{Estrogens}.$
Anastrozole, an aromatase inhibitor used in breast cancer treatment, blocks estrogen synthesis, illustrating how estrogen synthesis can be pharmacologically modulated.

Synthetic estrogens and progestogens used in pills

Key synthetic hormones discussed:

Synthetic estrogen: ethyl estradiol (EE) is the main estrogen used in earlier pills; newer pills may contain estradiol valerate or estradiol hemihydrate, which are metabolized in vivo to natural estrogen forms. Mesterol is mentioned as a prodrug that is metabolized to ethinyl estradiol in the liver.
Synthetic progestogens (progestogens): a wide range is listed and categorized by structural origin (from progesterone, from testosterone, and from aldosterone antagonists). A practical categorization links these progestogens to the generations of pills and highlights androgenic activity for some agents (e.g., norethindrone and levonorgestrel have androgenic activity), while later generations sought to reduce androgenic effects.
The fourth generation includes progestogens related to spironolactone (e.g., trospirenone), which have anti-mineralocorticoid activity and some antiandrogenic activity, plus potent antiproliferative actions on the endometrium.
The speaker emphasizes that the generation-based categorization is imperfect but provides a useful framework for understanding how different progestogens were developed to balance efficacy, lipid effects, and adverse effects.

Generations of progestogens and their implications

The speaker outlines the evolution of progestogens across generations, with specific examples and implications:

First generation: high estrogen dose (~50 μg EE) and relatively low-potency progestogens; associated with many unwanted effects.
Second generation: reduced estrogen dose to ~30–35 μg and introduction of more potent progestogens (e.g., levonorgestrel, norethindrone). These progestogens had androgenic activity and adverse lipid effects (altering LDL/HDL).
Cyproterone (anti-androgenic) was developed in the 1970s to counteract androgenic effects.
Third generation: progestogens such as norgestimate, desogestrel, and gestodene were developed to mitigate lipid-related adverse effects, but were found to be associated with an increased risk of thromboembolism (an estrogenic effect). The absolute risk remains small but clinically significant.
In the 1990s, estrogen doses were reduced again to ~120 μg to further offset thromboembolic risk.
Fourth generation: spironolactone-like progestogens (e.g., trospirenone) with anti-mineralocorticoid and antiandrogenic properties, and strong antiproliferative effects on the endometrium.

How estrogen and progestogen components act at the receptor level

Mechanisms of action at the cellular level:

Estrogen receptors: estrogens cross the cell membrane (lipophilic) and bind to intracellular receptors. The receptor–ligand complex translocates to the nucleus, binds to hormone response elements in DNA, and modulates transcription and translation to influence many genes. This leads to many physiological effects, both desired and undesired.
Progestogens act similarly to estrogens by modulating nuclear receptors; they have a slower onset (hours to days) due to genomic effects.
A notable interaction: estrogens promote progestin (progestogen) receptor synthesis, whereas progestogens can inhibit estrogen receptor synthesis. This reciprocal regulation can influence conditions such as endometriosis.

Hormonal generation and receptor interactions: practical implications

The combination of estrogens and progestogens exerts multiple, overlapping actions on the hypothalamic–pituitary–ovarian axis and peripheral tissues.
Estrogens generally exert positive feedback on endometrium proliferation during the follicular phase but negative feedback on the hypothalamus/pituitary control of FSH and LH in certain contexts; progestogens promote endometrial secretory changes and cervical mucus modulation.
The metabolic stability of synthetic hormones supports oral administration; natural estrogens and progestogens are rapidly metabolized in the liver, necessitating stable synthetic analogues.

Pharmacokinetics and pharmacodynamics: ingredients in pills

Ethinyl estradiol (EE) is the dominant synthetic estrogen in many pills; newer formulations may use estradiol valerate or estradiol hemihydrate (converted to natural estrogens in vivo).
Progestogens vary widely in structure and origin (progesterone-derived, testosterone-derived, and aldosterone antagonist-derived). The generation classification roughly reflects chemical lineage and pharmacologic properties, including androgenic activity and lipid effects.
Mesterolone is noted as a prodrug that is converted to ethinyl estradiol in the liver.
Trospirenone stands out for anti-mineralocorticoid and antiandrogenic activity and potent antiproliferative effects on the endometrium.

Mechanisms of contraception: how pills prevent pregnancy

The menstrual cycle is governed by a hypothalamic–pituitary–ovarian axis:

Hypothalamus releases gonadotropin-releasing hormone (GnRH), a decapeptide (10 amino acids long).
GnRH stimulates the anterior pituitary to secrete the gonadotropins: FSH and LH.
FSH promotes follicular development; LH surge triggers ovulation mid-cycle.
After ovulation, the corpus luteum forms and secretes progesterone, contributing to endometrial changes.
Ovarian hormones exert negative feedback on the hypothalamus and pituitary, shaping cycle dynamics.

Classical menstrual-cycle physiology (simplified)

Follicular phase: rising estrogen from developing follicles leads to endometrial thickening and vascularization.
Mid-cycle: LH surge leads to ovulation.
Luteal phase: corpus luteum produces progesterone, stabilizing the endometrium for potential implantation.
If no pregnancy occurs, the drop in ovarian hormones initiates menses; if pregnancy occurs, hormone support continues.

How estrogens and progestogens suppress the cycle and prevent implantation

Estrogens in combination pills suppress FSH, preventing follicular development and thus ovulation in most cycles.
Progestogens suppress the LH surge, which is essential for ovulation.
Progestin-only pills may reduce ovulation but do so unreliably, with ovulation suppressed in up to about sixty percent of cycles in some cases.
Downstream effects include:
- Cervical mucus becomes hostile to sperm, reducing sperm penetration.
- Endometrial receptivity is reduced, making implantation more difficult.
- Altered contractility of the fallopian tubes, affecting ovum and sperm transport.

Efficacy: how effective are hormonal contraceptives

Combined oral contraceptives (COCs) are extremely effective with perfect use: approximately $ext{efficacy} <br>ightarrow 0.98+$ (i.e., 98% or higher).
Long-acting progestogen-only methods are even more effective, typically exceeding 99% effectiveness.
Typical-use effectiveness is lower due to non-perfect adherence: roughly 4–7 pregnancies per 100 users per year.
These figures illustrate that progestogen-only methods can be extremely effective when used correctly, and that overall effectiveness depends on user adherence.

Non-oral hormonal contraceptives and monophasic preparations

Monophasic preparations: examples exist with a constant dose of ethinyl estradiol (the estrogen component) and varying progestogens; the slide notes that specific non-examined progestogens exist beyond those listed.
Non-oral hormonal contraceptives include the combined patch and vaginal ring, as well as implants, intrauterine devices (IUDs), and injectable forms (injectable depot medroxyprogesterone acetate).
The presenter emphasizes familiarity with a broad range of progestogens for clinical counseling, even though not all are examinable in the current session.

Practical implications: choosing a contraceptive

Reasons for multiple progestogens and formulations include balancing androgenic activity, lipid effects, thromboembolism risk, and endometrial antiproliferative properties.
Some progestogens have androgenic activity (e.g., norethindrone, levonorgestrel), which can affect acne, greasy skin, or lipid profiles in some individuals.
Anti-androgenic options (e.g., cyproterone) can be advantageous for specific symptoms such as acne or hirsutism but may carry other risks.
For patients with concerns about thromboembolism, the choice of progestogen and estrogen dose is important; third-generation progestogens were associated with higher thromboembolism risk (absolute risk remains small) and influenced by estrogen dose.
Trospirenone (a fourth-generation progestogen) brings anti-mineralocorticoid and antiandrogenic properties together with strong endometrial antiproliferative effects.

Ethical, philosophical, and real-world implications

The pill’s historical role as a symbol of female liberation is discussed, with contemporary debates recognizing that some individuals may view hormonal contraception differently or reject it entirely.
The availability of contraception and its cultural framing have evolved; access, autonomy, and informed choice are central to discussions of contraception in modern healthcare.

End of video: learning outcomes and take-home messages

Hormonal contraceptives are primarily synthetic analogs of estrogens and progestogens.
They work by suppressing the hypothalamic–pituitary–ovarian axis, thickening cervical mucus, reducing endometrial receptivity, and altering fallopian-tube contractility.
When used perfectly, they are highly effective; with typical use, effectiveness is reduced but remains substantial.
Hormonal contraception is increasingly delivered through non-oral routes to improve adherence and effectiveness.
You should be able to describe endocrine control of the menstrual cycle, give examples of synthetic estrogens and progestogens, outline receptor- and cellular-level mechanisms, and indicate effectiveness with perfect use.

Learning outcomes for the second video (gray text in the transcript)

The gray-out learning outcomes include describing the endocrine control of the menstrual cycle, providing examples of synthetic estrogens and progestogens, outlining mechanism of action at receptor, cellular, and physiological levels, and indicating the effectiveness of hormonal contraception with perfect use.

Non-examinable but useful context

The speaker emphasizes that beyond the listed progestogens, there are additional synthetic progestogens used in practice, and newer agents are continually introduced; thus, the list in the slides may be out of date.

Quick reference: key numerical and formula-like points

Endogenous estrogens: estradiol, estrone, estriol.
Endogenous progestogen: progesterone.
Major estrogen dose in first-generation pills: $50\,\mu\mathrm{g}$ of ethinyl estradiol.
Subsequent reduction in estrogen dose to $30-35\,\mu\mathrm{g}$ .
Later generation pills used around $120\,\mu\mathrm{g}$ estrogen in some formulations.
Long-acting progestogen-only methods: efficacy > $0.99$ (i.e., >99%).
Combined pills: perfect-use efficacy ≈ $98\%$ or higher; typical-use pregnancies: $4-7$ per 100 users per year.
Generational notes: 1st gen (high estrogen, lower progestin potency); 2nd gen (more potent progestogens but potential lipid and androgenic effects); 3rd gen (norgestimate, desogestrel, gestodene) with higher thromboembolism risk; 4th gen (trospirenone) with anti-mineralocorticoid and antiandrogenic properties.
Mechanistic summary: estrogens inhibit FSH; progestogens inhibit LH surge; progestin-only pills may prevent ovulation in some cycles (up to about 60%); combined regimens typically suppress ovulation in most cycles.

Key takeaways for exam prep

Be able to explain how the hypothalamic–pituitary–ovarian axis is modulated by estrogens and progestogens in COCs and POPs.
Recognize the major synthetic hormonal components: EE as a primary estrogen; various progestogens with differing structures and activities.
Understand the generation-based design of progestogens and the clinical implications (thromboembolism risk, lipid effects, androgenic effects, endometrial antiproliferative action).
Distinguish between progestin-only and combined regimens in terms of mechanism (ovulation suppression reliability) and practical effectiveness.
Be prepared to discuss the ethical and societal dimensions of contraception highlighted in the talk (liberation vs. rejection of hormonal contraception).

Exam-style prompts inspired by the transcript

Describe how estrogen and progestogen components act to prevent ovulation and create a hostile environment for implantation.
Compare and contrast first-generation versus third-generation progestogens in terms of estrogen dose, lipid effects, and thromboembolism risk.
Explain why non-oral routes of administration may improve contraceptive effectiveness in real-world use.
Discuss the ethical and societal considerations of hormonal contraception as a symbol of liberation, including modern perspectives that challenge or reject its use.

Terminology recap

Progestogen vs progestin: terminology differences by region; mechanism defined by action on nuclear receptors and downstream gene expression.
Endometrial antiproliferative effects and antiproliferative actions on the endometrium: important for contraceptive efficacy.
Anti-mineralocorticoid activity: a feature of trospirenone, contributing to diuretic-like effects and potential metabolic advantages.

Final note

This set of notes captures the breadth of the transcript, including hormone biology, pharmacology, generation-based design of progestogens, mechanism of action, efficacy data, practical considerations, and broader ethical context. The second video is expected to delve deeper into statistics and real-world data. Students should be able to connect the endocrine control of the menstrual cycle to the various mechanisms by which hormonal contraceptives exert their effects and to compare different formulations on the basis of their clinical properties.