Endocrine & oxytocin


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Endocrine & oxytocin

  1. 1. Endocrine Pharmacology By; Seyoum Gizachew (B.Pharm., MSc.) 1
  2. 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. 2
  3. 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. 3
  4. 4. Table: Hypothalamic Releasing and Inhibiting Hormones that regulate the anterior pituitary Table: Pituitary Hormones 4
  5. 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. 5
  6. 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. 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. 7
  8. 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. 8
  9. 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. 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. 10
  11. 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. 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. 12