Summary

In study session V you have learnt

• Histamine is found in the central nervous system, in the gastric mucosa, and in other peripheral tissues. The highest concentrations of histamine are found in the storage granules of circulating basophiles and mast cells throughout the body. Histamine normally plays a major role in the secretion of hydrochloric acid by parietal cells in the stomach.
• Conditions that release histamine include tissue injury, allergic reactions, drugs and other foreign compounds.
• H1-receptor antagonists includes diphenhydramine promethazine, and hydroxyzine have a multitude of therapeutic uses: suppression of allergic symptoms (e.g., urticaria, rhinitis, conjunctivitis); vertigo, nausea, and vomiting (e.g., motion sickness); sedation and suppression of cough
• H2-receptor includes cimetidine, famotidine, and ranitidine. These agents competitively inhibit histamine binding to H2-receptors, thereby reducing gastric acid output and raising gastric pH.
• Cimetidine may reduce hepatic blood flow and binds to the cytochrome P-450 system. These effects slow the metabolism of drugs, including lidocaine, propranolol, diazepam, theophylline, Phenobarbital, warfarin, and phenytoin.
• Corticosteroids have an increasing application of steroid therapy during perioperative period for various purposes. Some of the current indications are Perioperative replacement therapy, anti-inflammatory uses and hyper-reactive airway, post operative nausea and vomiting, analgesia adjunct, day care surgery, anaphylaxis, septic shock, cerebral edema, spinal cord injury and various surgical causes.
• Adverse effect of steroids includes of gastrointestinal bleeding, super- infections, and hyperglycemia. Other potential adverse effects include sodium and water retention, hypokalemia, and reduced wound healing, although these are not typically reported.