Gastrointestinal Drugs and Antacids

Study Notes

Gastrointestinal, Antiemetic, and Antispasmodic Drugs

Antihistamines

Cimetidine: an antiulcer agent (histamine H2-receptor antagonist) that can decrease acid secretion
Indications:
- Peptic ulcers
- GERD
- Prophylaxis of pulmonary aspiration in anaesthesia
- Gastritis in combination with other agents (e.g. antacids)
Usual presentation: 200mg tablet
Dosage and duration:
- 200-400mg single dose 1hr before operation/anaesthesia
- 200mg BD to TDS up to 3 days to 2 weeks
- Child dose: 10-20mg/kg/day (in divided doses)
Adverse effects:
- Gynecomastia (0.3-4%)
- Antiandrogen: may cause feminization and sexual dysfunction in males
- Diarrhea, headache, dizziness, skin rash, fever (less than 2%)
Remarks:
- Sometimes comes in injectable form
- Pregnancy: may be acceptable
- Lactation: not recommended

Ranitidine

Discontinued in some countries
Usual presentations:
- Injection: 25mg/ml of 2ml ampoules
- 75, 150, or 300mg tablets
Indications:
- Gastroesophageal reflux disease
- Gastric ulcer, benign
- Esophagitis, gastritis
Usual dosages and duration:
- 150mg PO BD or TDS
- 50mg IM/IV 12hrly or up to 6hrly
- Child dose: 5-10mg/kg/day once or 12hrly
- According to clinical response. If not responsive, use PPIs
Adverse effects and cautions:
- Headache (3%)
- Use with caution in renal and hepatic impairment
- IM administration does not need to be diluted, but IV injection is better diluted to make 20cc
Remarks:
- Pregnancy: may be acceptable
- Lactation: contraindicated

Description

This quiz covers different types of gastrointestinal drugs, including antiemetic and antispasmodic drugs, antiulcer agents, and antacids. It explores their indications, dosages, and uses in peptic ulcers, GERD, and other conditions.