Parenteral Manual

DiphenhydrAMINE

Disclaimer: Official controlled document is the CHEO online copy. It is the responsibility of user to ensure that any paper copy version is the same as the online version before use.

Alternate Name(s): 
BENADRYL®
Classification: 
Antihistamine
Original Date: 
August 2005
Revised Date: 
December 2019
Indications: 
  • Symptomatic relief of allergic symptoms caused by histamine release
  • Prevention and treatment of nausea, vomiting or vertigo associated with motion sickness
  • Prevention and treatment of drug-induced extrapyramidal reactions
Reconstitution and Stability: 
  • Available as a 50 mg/mL solution. Protect from light
  • Stable 91 days at room temperature or in fridge when diluted in 50 mL of 0.9% NaCl or D5W
Compatibility: 

- Solutions Compatible: dextrose up to D10W, 0.9% NaCl, dextrose-saline combinations, ringer's solution, ringer's lactate

- Additives/Above Cassette Compatible: morphine (for 15 minutes), dimenhydrinate, fentanyl, glycopyrrolate, hydromorphone, ranitidine

- Y-site Compatible: acyclovir, fluconazole, ondansetron, KCl (up to 40 mmol/L), TPN (amino acids/dextrose), meropenem

Incompatible: amphotericin B, dexamethasone, thiopentol

Administration: 

(For approved routes of administration by nursing personnel, refer to Policy for the Administration of Intravenous Medications.)

SC

NO  - except for Palliative Care Service
IM YES
Usual dilution: 50 mg/mL
IV Direct

YES
Usual dilution: 5 mg/mL
Infusion time: 5 minutes
Infusion rate: do not exceed 25 mg/minute
IV Intermittent Infusion YES
Usual dilution: 5 mg/mL
Infusion time: 10-15 minutes
Infusion rate: do not exceed 25 mg/minute
IV Continuous Infusion YES
Usual dilution: 5 mg/mL
Dosage: 

(For neonatal dosages, refer to Neonatal IV Drug Manual.)

Pediatric:  

  • 5 mg/kg/day IM/IV ÷ Q 6-8 hours PRN
  • Usual dose 1 mg/kg per dose
  • Maximum: 50 mg/dose

Adult:   

  • 25-50 mg/dose IM/IV Q 4 hours PRN
Potential hazards of parenteral administration: 
  • Irritation at IM injection site - rotate site
  • Avoid SC or perivascular injection due to irritation effects
  • Anaphylaxis (rarely)
  • CNS depression, drowsiness/sedation, dryness of mouth                                               
  • Paradoxical CNS stimulation may occur in children                                      
  • Hypotension, palpitations, tachycardia
  • Chest tightness, thickened bronchial secretions, wheezing
Notes: 
  • Changes in blood pressure and ECG
  • Caution in patients with asthma, chronic obstructive pulmonary disease, cardiac disease, hypertension, narrow angle glaucoma
  • Potentiates side effects of anticholinergics and CNS depressants                        
  • Dosage adjustment may be necessary in severe renal impairment                      
  • Should not be used in acute asthma attacks

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