Friday 21 August 2015

Continuation of adjuncts in anesthesia

In continuation with the topic "adjuncts in anesthesia " today we shall go with antacid
And anti emetics .These drugs attain special significance in emergency surgeries or in
patients with delayed gastric emptying time,yesterday I had a emergency LSCS and I had to administer these drugs before shifting the patient to OT.

Antacids
 Mechanism of action: Antacids neutralise the acidity of gastric fluid by providing a base (usually
hydroxide ,carbonate,bicarbonate,citrate etc) that reacts with hydrogen ions to water.
Clinical uses:
1) Treatment of gastric and duodenal ulcers,GERD and Zollinger-Ellison syndrome
2) Antacids provide protection against the harmful effects of aspiration pneumonia by raising the
pH of gastric contents. They have an immediate effect but they also increase the gastric volume
3) There are 2 types of antacids -particulate  and non particulate,the particulate ones cause lung
function abnormalities on aspiration.
4) Nonparticulate antacids are much less damaging to lung alveoli if aspirated,timing is very critical
for Nonparticulate antacids which lose their effectiveness 30 to 60 60 min after ingestion.
Dosage: The usual adult dose is 0.3 M solution of sodium citrate is 15 to 30ml orally 15 to 30 min
prior to induction.
Drug interaction: the rate of absorption of digoxin,cimetidine and rantac is slowed whereas the
rate of elimination of phenobarbital is quickened.

Metoclopromide
 Mechanism of action: Metoclopromide acts peripherally as a cholinomimetic and centrally as a
domaminergic antagonists.Ita action as a pro kinetic agent in the upper gastrointestinal effect is
not dependent on vagal innervation

Clinical uses:
Metoclopromide increases the lower esophageal sphincter tone by enhancing the stimulatory effects
of Acetylcholine
It speeds the gastric emptying time and lowers gastric fluid volume.
Treatment of gastroparesis in diabetic patients  and GERD due to the above effects.
Prophylaxis for those at risk of aspiration pneumonia
It acts as a antiemetic due to blocking of domaminergic receptors in chemoreceptors trigger zone
 Is helpful in treatment of cancer therapy
It may provide some degree of analgesia in conditions of smooth muscle spasm like biliary and
Uterine colic

Side effects:

Rapid iv injection may cause abdominal cramping .
Contraindicated in patients of intestinal obstruction
It may induce a hypertensive crisis in patients with pheochromocytoma
Sedation,nervousness and extrapyramidal signs are less common
Avoided in patients of Parkinsonism
It may result in hypotension and arrhythmias

Dosage:
An dose is 10 to 20 mg of Metoclopromide is effective orally
0.25mg/kg is effective im/iv dose
Higher doses used in 1 to 2mg/kg is used in cancer chemotherapy

Drug interaction: Anti muscarinic drugs like atropine,glycopyrrolate block the GI effects of Metoclopromide
Concurrent usage with phenothiazine and butyrophenones can increase the extrapyramidal
side effects.



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