What antiemetic can be given intramuscularly (IM)?

Antiemetics That Can Be Administered Intramuscularly (IM)

Prochlorperazine and metoclopramide are the primary antiemetics that can be safely and effectively administered via the intramuscular (IM) route.

Prochlorperazine (IM)

Prochlorperazine is a well-established antiemetic that can be administered intramuscularly for rapid control of nausea and vomiting:

• Dosage: 5-10 mg IM injected deeply into the upper, outer quadrant of the buttock 1
• Frequency: Can be repeated every 3-4 hours as needed
• Maximum daily dose: Should not exceed 40 mg per day 1
• Special considerations:
  • Lower doses (5 mg) may be appropriate for elderly patients who are more susceptible to hypotension and neuromuscular reactions
  • Should be injected deeply to avoid local irritation
  • Not recommended for pediatric patients under 20 pounds or under 2 years of age 1

Metoclopramide (IM)

Metoclopramide is another effective antiemetic option available for IM administration:

• Dosage: 10 mg IM for adults 2
• Use cases:
  • Prevention of postoperative nausea and vomiting (administered near the end of surgery)
  • Management of nausea and vomiting associated with gastroenteritis
  • Diabetic gastroparesis (when oral administration is not feasible)
• Caution: Associated with risk of extrapyramidal symptoms, particularly in young patients 3

Other IM Antiemetic Options

Several other antiemetics can be administered via the IM route:

• Promethazine: 25-50 mg IM every 6 hours as needed 4
• Haloperidol: 0.5-2 mg IM every 4-6 hours for breakthrough nausea and vomiting 4
• Diphenhydramine: Often used in combination with other antiemetics at 50 mg IM to prevent or treat extrapyramidal side effects 5
• Droperidol: 1 mg IM (often used in combination therapy) 5

Combination Therapy

For severe or refractory nausea and vomiting, combination therapy may be more effective:

• A five-drug combination of metoclopramide, dexamethasone, droperidol, lorazepam, and diphenhydramine has shown efficacy for chemotherapy-induced nausea and vomiting, with droperidol administered IM 5
• Dexamethasone (IM) can be combined with metoclopramide (IM) for delayed chemotherapy-induced nausea and vomiting 6

Clinical Considerations

When selecting an IM antiemetic:

1. Patient factors:

   • Age (elderly patients may require lower doses)
   • Previous history of extrapyramidal symptoms
   • Underlying conditions (cardiovascular disease, seizure disorders)

2. Potential side effects:

   • Extrapyramidal symptoms (more common with metoclopramide, especially in young patients)
   • Sedation (more common with promethazine)
   • Hypotension (monitor closely, especially with prochlorperazine)

3. Administration technique:

   • Always inject deeply into the upper, outer quadrant of the buttock
   • Avoid subcutaneous administration due to local irritation
   • Monitor injection site for pain or irritation

Breakthrough Treatment

For breakthrough nausea and vomiting not responding to initial IM therapy, consider:

• Adding an agent from a different drug class
• Switching to IV administration if available
• Using scheduled rather than PRN dosing for persistent symptoms 4

Remember that IM administration provides a useful route when oral medications cannot be tolerated and IV access is not available or practical.