WEEK 2: DRUGS IN PREGNANCY AND DELIVERY Flashcards
Describe the hormonal control of the female reproductive system.
- Gonadotropin-Releasing Hormone (GnRH):
-GnRH is produced by the hypothalamus in the brain.
-It stimulates the anterior pituitary gland to release two important hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- Follicle-Stimulating Hormone (FSH):
-FSH is produced by the anterior pituitary gland.
-It stimulates the growth and maturation of ovarian follicles, which are small sacs in the ovaries that contain developing eggs.
- Luteinizing Hormone (LH):
-LH is also produced by the anterior pituitary gland.
-In the early part of the menstrual cycle, LH stimulates the ovarian follicles to produce estrogen.
-In the middle of the cycle, it triggers ovulation, the release of a mature egg from the ovary.
-After ovulation, LH stimulates the formation of the corpus luteum, which secretes progesterone.
- Estrogen:
-Estrogen is produced primarily by the developing ovarian follicles.
-It is responsible for the growth and thickening of the uterine lining (endometrium) during the menstrual cycle.
-Estrogen also influences secondary sexual characteristics, such as breast development and the regulation of the menstrual cycle.
- Progesterone:
-Progesterone is produced by the corpus luteum in the ovary (after ovulation) and later by the placenta during pregnancy.
-It prepares the uterine lining for the potential implantation of a fertilized egg.
-Progesterone helps maintain the pregnancy by preventing the shedding of the endometrial lining.
-It has a thermogenic effect which rises the body temperature by 0.5 degrees Celsius which is maintained throughout the luteal phase
- Human Chorionic Gonadotropin (hCG):
-hCG is produced by the placenta during pregnancy.
-It stimulates the corpus luteum to continue producing progesterone, which is vital for maintaining the early pregnancy.
State the 2 types of ovulation stimulants.
*Clomiphene citrate
*Gonadotropins
Describe the MOA of Clomiphene citrate.
- Estrogen Receptor Modulation:
Clomiphene citrate acts as an antagonist on estrogen receptors in the hypothalamus and pituitary gland. It competes with endogenous estrogen, preventing it from binding to these receptors.
This binding results in a reduction in negative feedback to the hypothalamus and pituitary gland, as these tissues sense lower estrogen levels.
The reduced negative feedback leads to an increase in gonadotropin-releasing hormone (GnRH) production from the hypothalamus.
- Gonadotropin Release:
The increased GnRH stimulates the anterior pituitary gland to secrete higher levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
Elevated LH and FSH levels subsequently promote the development and maturation of ovarian follicles.
- Ovulation Induction:
The developed follicles can lead to the release of an egg from the ovary, a process known as ovulation.
Clomiphene citrate’s primary purpose is to induce ovulation in women who do not ovulate regularly or have irregular menstrual cycles due to conditions like polycystic ovary syndrome (PCOS) or hypothalamic amenorrhea.
Describe the timing and monitoring of the clomiphene citrate treatment.
*Given as a 5-day treatment given 50mg
*Monitored with ultrasound to access size and number of developing follicles
*Can also be monitored by using the urine estradiol and LH levels
*There should be
State the side effects of Clomiphene citrate.
*Reversible ovarian enlargement
*Hot flashes
*Multiple pregnancy due to multiple ovulations
Gonadotrophins as ovulation stimulants.
They have several pharmaceutical forms.
*Menotropins and Urofollitropins
What is the difference between these two?
Define the following:
*Lutropin alfa
*Follitropin alfa
State the 3 ovulation induction protocol using Gonadotropins
*Accepted alternative to clomiphene citrate after using their 4-6 cycles
*Subcutaneous or IM injection
Several pharmaceutical forms
*Extracted from urine of post-menopausal women
*Menotropins and Urofollitropins
-Menotropins contain both FSH and LH
-Urofollitropins contain FSH only
-Lutropin alfa (Recombinant form of human LH)
-Follitropin alfa (Recombinant form of human FSH)
Ovulation induction protocols
- Inhibition of endogenous gonadotropin: By giving GRH antagonist
- Follicle development: injection with FSH
- Ovulation induction: injection with LH
State the side effects of Gonadotropins.
*Multiple birth: can be complicated by
*Ovarian hyperstimulation syndrome
-Ovaries swell and release fluid in the body
-Can cause ascites in the hydrothorax
Describe the motility of the uterus.
*Rhythmic contractions of the uterus during labor
*Originate from the myometrium
Describe the hormonal regulation of uterine contractions by progesterone.
The electrophysiological activity of the uterus during pregnancy is regulated by sex hormones
*Progesterone reduces the excitability of the myometrial cells, promote uterine relaxation, and keeps the baby quiescent during pregnancy.
-It increases the release of calcitonin and lowers calcium levels
-decreases the sensitivity to oxytocin
-Decreases prostaglandin synthesis
Describe how the normal labor is induced.
NORMAL LABOUR INDUCTION
*Baby stretches the uterus, causing release of placental Corticotropin-releasing hormone by the placenta
*There is stimulation of estriol release
-Estriol inhibits progesterone synthesis
-Upregulates myometrial gap junctions allowing the electrical signals to travel through the myometrium
-Upregulates oxytocin receptors which is induce uterine contractions.
What are uterotonics?
State the 2 uses of uterotonics.
State the 3 examples uterotonic drugs.
-Drugs which stimulate uterine contractions.
-Induce labor
-Reduce postpartum hemorrhage
Oxytocin, prostaglandins, ergometrine
Oxytocin as a uterotonic.
Where is oxytocin released from?
Oxytocin receptors are Gg-protein coupled. Describe how it induces the uterine contractions.
Why is oxytocin administered parenteral?
State the adverse effects of oxytocin.
-It is a neurohypophyseal hormone.
-It is released from the posterior pituitary gland
-It is stimulated by cervical
-Oxytocin receptors are Gg-protein coupled
*
-Available in brand names such as Pitocin and Syntocinon.
-Administered intramuscularly or intravenously.
*They are neuropeptides so can be degraded by the GIT
Adverse effects:
*Fetal distress: sustained uterine contraction in uterus and impede blood from on the placenta to the fetus.
*Maternal hypotension and tachycardia: Oxytocin is a vasodilator
State the other functions of oxytocin apart from inducing uterine contractions.
*Nipple stimulation stimulates oxytocin release by electric breast pump
*Oxytocin stimulates lactation contract cells in the mammary glands and results in milk let out
*Oxytocin promotes social bonding, its receptors found in limbic system
Describe the MOA of PROSTAGLANDINS in promoting muscle contraction.
State the examples of prostaglandin drugs.
State the adverse effects of prostaglandins.
Contract the uterus at all stages of pregnancy.
*Alter membrane permeability and increase intracellular calcium
*Promote formation of gap junctions
*Upregulate expression of oxytocin receptors in the uterus
*Used for induction of labor or as abortifacients.
Examples: Dinoprostone (E2); Carboprost (F); Gemeprost, Misoprostol (E1)
Adverse effects:
Can result in systemic muscle contractions hence resulting in the following:
*Asthma-like attack
*Hypertension
*Abdominal cramps
*Can result in fever as they are pyrogens.
Describe the MOA of ERGOMETRINE as a uterotonic.
State the adverse effects of ergometrine.
*Isolated from a fungus called ergot
-There is some evidence that it stimulates the alpha and serotonin receptors.
-It contracts both the uterine and the vascular smooth muscle.
ADVERSE EFFECTS
-Powerful vasoconstrictor (Hypertension and vasospastic disease)
Hallucinogenic at high doses (Serotonergic effect)
