What are the typical components of a GI (Gastrointestinal) cocktail and how are they written as a prescription?

GI Cocktail Components and Prescription Writing

The traditional GI cocktail contains three components: liquid antacid (30 mL), viscous lidocaine 2% (10-20 mL), and an anticholinergic agent such as Donnatal (10 mL), though evidence shows that antacid alone provides equivalent symptom relief. 1

Standard Prescription Format

Traditional Three-Component GI Cocktail

Prescription #1: Antacid Component

• Maalox or equivalent liquid antacid
• Dispense: 30 mL per dose
• Sig: Mix with other components below, give once in emergency department 2, 3

Prescription #2: Topical Anesthetic

• Lidocaine viscous 2% solution
• Dispense: 10-20 mL per dose
• Sig: Mix with antacid and anticholinergic, swish and swallow once 1, 2

Prescription #3: Anticholinergic

• Donnatal (phenobarbital/hyoscyamine/atropine/scopolamine combination)
• Dispense: 10 mL per dose
• Sig: Mix with above components, give once 1, 2

Combined administration: Mix all three components together and have patient swish in mouth for 30 seconds before swallowing 3

Evidence-Based Simplification

The most important clinical finding is that plain liquid antacid alone provides equivalent pain relief compared to the full three-component cocktail. 2 A randomized, double-blind trial of 113 patients demonstrated no statistically significant difference between antacid alone (25 mm VAS decrease), antacid plus Donnatal (23 mm decrease), or the full three-component cocktail (24 mm decrease) 2. This finding is supported by systematic review evidence recommending antacid alone as preferred treatment 4.

Simplified Evidence-Based Prescription

For routine dyspepsia in the emergency department:

• Maalox or Mylanta liquid antacid 30 mL
• Sig: Swish and swallow once, may repeat in 30 minutes if needed 2, 4

When to Consider Additional Components

Add viscous lidocaine only when:

• Severe esophageal pain is the predominant symptom 1
• Patient has failed antacid alone after 30 minutes 4
• No contraindications to topical anesthetics exist 4

Add Donnatal with extreme caution due to:

• Anticholinergic side effects including dry mouth, urinary retention, and tachycardia 5
• Lack of proven benefit over antacid alone 2
• Phenobarbital content causing sedation 2

Critical Safety Warnings

Relief of chest pain or epigastric discomfort with a GI cocktail does NOT rule out acute coronary syndrome and cannot be used to exclude cardiac ischemia. 1 The American College of Cardiology explicitly warns that therapeutic response has no diagnostic value, as sublingual nitroglycerin relieved symptoms in 35% of patients with documented ACS versus 41% without ACS 1.

Mandatory cardiac workup regardless of GI cocktail response:

• ECG within 10 minutes of presentation 1
• Serial troponins at 0 and 3-6 hours 1
• Complete risk stratification using validated tools 1
• Do not discharge based on symptom relief alone 1

Common Prescribing Pitfalls

Avoid co-administration timing errors: In one retrospective study, 68% of patients received other medications (most commonly narcotics in 56% of cases) at a median of only 9 minutes before the GI cocktail, making it impossible to determine which intervention provided relief 3. When narcotics, nitroglycerin, or antiemetics are given nearly simultaneously, the GI cocktail's effect cannot be isolated 3.

Proper sequencing:

• Give GI cocktail first as a single intervention 3
• Wait 30 minutes to assess response 2
• Add other medications only if GI cocktail fails 3
• Document response to each intervention separately 3

Contraindications to viscous lidocaine:

• Known lidocaine allergy 4
• Severe hepatic dysfunction (lidocaine is hepatically metabolized) 4
• Methemoglobinemia risk factors 4

Contraindications to Donnatal:

• Narrow-angle glaucoma 5
• Obstructive uropathy 5
• Myasthenia gravis 5
• Elderly patients at risk for anticholinergic toxicity 5

Alternative Topical Anesthetic

Benzocaine (Hurricane spray) provides equivalent efficacy to viscous lidocaine with faster onset. 6 A prospective randomized trial of 82 patients showed no statistical difference in pain relief between benzocaine and viscous lidocaine at 5,15, and 30-minute assessments, with both groups achieving significant improvement (p < 0.001) 6.

Benzocaine prescription alternative:

• Benzocaine 20% spray (Hurricane)
• Dispense: 2-3 sprays to oropharynx
• Sig: Spray to back of throat, then swallow 30 mL antacid 6

Antacid Selection and Pharmacology

Aluminum-magnesium combination antacids (Maalox, Mylanta) are preferred over single-agent formulations. 7 Magnesium salts cause diarrhea while aluminum salts cause constipation, so combination products balance these effects 7. Calcium carbonate provides rapid onset but can cause acid rebound and constipation 7.

Avoid in chronic renal failure: Aluminum-containing antacids should not be used long-term in patients with creatinine clearance <30 mL/min due to aluminum accumulation and neurotoxicity risk 7.

Drug interaction considerations: All antacids alter gastric pH and can reduce absorption of fluoroquinolones, tetracyclines, iron, and azole antifungals by 30-50% 7. Separate administration by at least 2 hours 7.

Documentation Requirements

Document the following in every case:

• Specific indication for GI cocktail administration 3
• Exact components and doses given 3
• Time of administration 3
• Response assessment at 30 minutes using objective pain scale 2
• Any co-administered medications and their timing 3
• Cardiac workup completed if chest pain was the indication 1