2. Introduction
• The metabolic effects of the different systems of the body:
– controlled by autonomic nervous system and the
secretions of the endocrine, or ductless glands.
• Hormones:
– heterogeneous group of chemicals,
– released into the blood stream and travel to all parts of the
body.
• The pharmacology of the individual hormones is of
importance,
– under or over production of the hormones can have
striking metabolic consequences.
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3. Introduction cont…
• The hypothalamus and pituitary gland function
cooperatively as master regulators of the endocrine
system.
– control reproduction, growth, lactation, thyroid and
adrenal gland physiology, and water homeostasis.
• Deficiency or overproduction of these hormones disrupts
this control.
• Clinical use of protein hormones in the past was limited;
– Preparations had to come from glands or urine.
• Recombinant DNA techniques and the development of
more stable analogues that can be injected in a depot form
– permit increased and more effective use of these
hormones.
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4. Table: Hypothalamic Releasing and Inhibiting Hormones that regulate the anterior pituitary
Table: Pituitary Hormones
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5. Uterine Stimulants/ Oxytocics
1. Oxytocin
• Is a cyclic 9–amino acid peptide
• Synthesized in the paraventricular nucleus of the
hypothalamus
• Transported to the posterior pituitary for storage.
• Its mechanism of action
– direct stimulation of oxytocin receptors found
on the myometrial cells.
• Contract uterine smooth muscle.
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6. • Also causes contraction of myoepithelial
cells surrounding mammary alveoli,
–leads to milk ejection.
• Circulates unbound in the plasma.
• half-life of approximately 5-15 minutes.
• primarily inactivated in the kidneys and
liver.
7. Oxytocin cont…
• Generally considered to be the drug of choice for
inducing labor at term.
• Successful in inducing and augmenting labor.
– In patients with labor disorders.
• Used following incomplete abortion (retention of parts of
the products of conception).
• may be used after full-term delivery to prevent or control
uterine hemorrhage.
• Oxytocin in high doses is used to induce abortion.
• Inappropriate use of oxytocin can lead to;
– uterine rupture,
– possibly maternal death.
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8. Oxytocin cont…
• Prolonged stimulation of uterine
contractions can result in the following fetal
adverse reactions:
–persistent uteroplacental insufficiency,
–sinus bradycardia, premature ventricular
contractions, other arrhythmias, and
–fetal death.
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9. Dosing;
• Induction of labor,
– initial infusion rate of 0.5–2 mU/min is increased
every 30–60 min (max. infusion rate is 20 mU/min).
• Postpartum uterine bleeding,
– 10–40 units are added to 1 L of 5% dextrose, titrate
infusion rate to control uterine atony.
– Alternatively, 10 units of oxytocin can be
administered by IM after delivery of the placenta.
10. 2. Ergometrine
• Ergot (Claviceps purpurea) is a fungus that
grows on rye.
–contains a surprising variety of
pharmacologically active substances
(Ergot alkaloids).
• In 1935, ergometrine,
–isolated and was recognised as the
oxytocic principle in ergot.
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11. Pharmacological actions:
• Ergometrine contracts the human uterus.
• Ergometrine also has a moderate degree
of vasoconstrictor action per se.
–reduce bleeding from the placental bed
(the raw surface from which the
placenta has detached).
12. Ergometrine cont…
• Can be given orally, IM or IV.
• Has a very rapid onset of action and its effect lasts for 3-6
hours.
• Unwanted effects:
– Vasoconstriction with an increase in blood pressure
associated with nausea, blurred vision and headache can
occur,
– vasospasm of the coronary arteries resulting in angina.
Dosing:
• Prevention and treatment of postpartum haemorrhage,
– IM injection: 200 mcg immediately after birth.
• Excessive uterine bleeding: Slow IV injection: 250-500 mcg
immediately after birth.
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