VPT 321: Veterinary Neuropharmacology (2+1)

CLINICAL USES OF PROSTAGLANDINS

Prostaglandins and their analogues are used infrequently because of their high cost.

• Abortion
  • Prostaglandins (PGF_2α )have a role to play in midterm abortion, though delayed and erratic action may be a problem - luteolysis. This activity of PGF_{2α ^{is used for}}  oestrous synchronization in cattle.
  • They convert oxytocin resistant midterm uterus to oxytocin responsive uterus.
  • There are many side effects. Eg: cramps, diarrhea, incomplete abortion so surgery must still be performed to remove residual tissue.
  • If the foetus is near term, these prostaglandins are used to induce labour. 
• Induction of parturition
  • Prostaglandins do not offer any advantage over oxytocin for induction of labour at term.
  • They are less reliable and show wider individual variation in action.
• Post partum haemorrhage 
  •  15-methylPGF_2α can be used in cases not responding to ergometrine or oxytocin.
• Peptic ulcer 
  • Stable analogues of PGE₁ and PGE₂ can be used for healing peptic ulcer especially when continuous use of NSAIDs is required. Eg: Misoprostal
  • Long term use of NSAIDs (e.g. aspirin) will cause reduced prostaglandin levels (since COX has been inhibited).
  • PG’s are required to maintain the viability of the gastric mucosal barrier.
• To avoid platelet damage
  • In cardiac surgery blood going into the heart lung bypass tends to clot, because platelets become activated as a result of the abnormal surface.
  • If PGI₂ is infused in the patient, the platelets will not aggregate because PGI₂ is anti-aggregatory.
  • After surgery, risk of bleeding is minimal because of the relatively short half life of PGI₂. However, the vasodilator effects of PGI₂ may cause an unwanted drop in blood pressure, which would cause a reflex tachycardia, which is undesirable especially after cardiac surgery.
• Patency of PDA
  • Prostaglandins can keep the ductus arteriosus open in newborn children who have a congenital abnormality of the aorta.
  • If the ductus arteriosus were to close in these babies, death would occur very quickly