GI Cocktail Dosage
The standard GI cocktail consists of 30 mL of liquid antacid (such as Maalox) combined with 10 mL of viscous lidocaine 2% and 10 mL of an anticholinergic agent (Donnatal), though evidence shows plain antacid alone is equally effective. 1, 2
Standard Formulation Components
The most commonly used GI cocktail formulation includes:
- Liquid antacid (Maalox or equivalent): 30 mL 2, 3
- Viscous lidocaine 2%: 10 mL 3
- Donnatal (anticholinergic): 10 mL 2, 3
Evidence-Based Recommendations
Plain antacid alone provides equivalent symptom relief compared to the full GI cocktail mixture. A randomized, double-blind trial demonstrated no statistically significant difference in pain relief between antacid alone (25 mm decrease on visual analog scale), antacid plus Donnatal (23 mm decrease), or the complete cocktail with lidocaine (24 mm decrease). 1
Alternative Topical Anesthetic
- Benzocaine (Hurricaine) can substitute for viscous lidocaine at equivalent doses with similar efficacy and speed of onset, showing no statistical difference in symptom relief at 5,15, and 30-minute intervals. 3
Clinical Considerations
When to Use Each Component
- For simple dyspepsia or heartburn: Use antacid alone (30 mL) as it provides equivalent relief without additional medication risks. 1, 4
- If topical anesthesia is desired: Add 10 mL viscous lidocaine 2% or equivalent benzocaine only at physician discretion in patients without contraindications. 4
- Anticholinergic addition (Donnatal) provides no additional benefit and should generally be avoided. 1
Important Pitfalls to Avoid
- Do not rely on symptom response to differentiate cardiac from gastrointestinal causes of chest pain. Studies show similar response rates in both admitted and discharged patients, making the "GI cocktail test" unreliable for diagnosis. 2
- Avoid co-administration with other medications within 9 minutes. In practice, 68% of patients receive other drugs (particularly narcotics, nitroglycerin, or antiemetics) close to GI cocktail administration, making it impossible to determine which agent provided relief. 2
- Be aware of lidocaine toxicity risk. The 10 mL dose of viscous lidocaine 2% contains 200 mg of lidocaine, which approaches maximum recommended doses, particularly in patients with hepatic dysfunction or those receiving other local anesthetics. 3