Dilution and Administration of Avil (Pheniramine) for IV Injection
Dilute pheniramine in at least 10 mL of 0.9% sodium chloride or 5% dextrose and administer slowly over 2-5 minutes to prevent seizures and hypotension. 1, 2
Recommended Dilution Protocol
- Dilute 1-2 mg/kg (maximum 50 mg) in 10 mL of either 0.9% sodium chloride or 5% dextrose in water before IV administration 1, 2
- The minimum dilution volume of 10 mL is critical—never administer undiluted IV push 2
- Both normal saline and D5W are acceptable diluents with equivalent safety profiles 2
Administration Rate and Technique
- Administer the diluted solution slowly over 2-5 minutes minimum 1, 2
- Rapid administration significantly increases the risk of seizures, hypotension, and respiratory suppression 1, 2
- Monitor vital signs and oxygen saturation continuously during and after administration 1
Dosing Parameters
- Adult and pediatric dose: 1-2 mg/kg per dose (maximum initial dose: 50 mg) 1, 2
- The IM route is acceptable when IV access is not immediately available, using the same dose 1
- For ongoing allergic conditions, oral dosing of 4-12 mg as a single nocturnal dose may be used 1
Critical Safety Considerations
Immediate Risks with Rapid Administration
- Seizures are the most serious acute complication of rapid IV push 1, 2
- Hypotension can occur, particularly with undiluted or rapid administration 1, 2
- Respiratory suppression and apnea, especially when combined with benzodiazepines or opioids 1, 2
- Paradoxical excitement or agitation, particularly in pediatric patients 1, 2
Role in Anaphylaxis Management
- Pheniramine should NEVER be used as monotherapy in anaphylaxis—epinephrine must be given first 2
- Pheniramine serves only as adjunctive second-line therapy after epinephrine and fluid resuscitation 1, 2
- Combination with H2-blockers (ranitidine 1 mg/kg diluted in 20 mL D5W over 5 minutes) is superior to H1-antihistamine alone in managing infusion reactions 3, 2
Common Clinical Pitfalls to Avoid
- Never give undiluted IV push—always dilute in at least 10 mL of compatible solution 2
- Never administer rapidly—use a minimum 2-minute infusion time to prevent seizures 1, 2
- Never use as monotherapy in anaphylaxis—epinephrine must be given first 2
- Monitor for respiratory depression, especially when combined with other sedative agents 1, 2
- Sedation is the most common side effect and should be anticipated 1
Contraindications and Special Precautions
- Avoid in severe hepatic disease, as sedative effects may precipitate hepatic coma 1
- Contraindicated in angle-closure glaucoma, prostatic hypertrophy, and urinary retention 1
- Avoid concomitant use with MAOIs and medications with anticholinergic effects 1
- Should be avoided in pregnancy, especially during the first trimester 1
- Should be avoided during lactation 1