Parenteral Manual


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Alternate Name(s): 
Original Date: 
August 2005
Revised Date: 
July 2013
  • For the treatment of various forms of hypertension when the oral route is not feasible
Reconstitution and Stability: 
  • Available as 20 mg/mL ampoules
  • Store at room temperature. Refrigeration may result in precipitation or crystallization 
  • Infusion solutions stable 24 hrs at room temperature
  • Undergoes colour changes in certain dextrose solutions and after contact with a metal filter (not recommended)

- Solutions Compatible: D10W and D20W, NS, dextrose-saline combinations, ringer's solution, ringer's lactate

- Additives/Above Cassette Compatible: no information

- Y-site Compatible: heparin, KCl (up to 40 mmol/L), verapamil

- Incompatible:  aminophylline, ampicillin, diazoxide, D5W, furosemide, hydrocortisone, phenobarbital


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

IV Direct

YES, BP monitoring.  Critical care areas only
Usual dilution: 1 mg/mL
Infusion time: 3-5 minutes
Infusion rate: do not exceed 5 mg/minute or 0.2 mg/kg/minute

IV Intermittent Infusion YES, BP monitoring
Usual dilution: 1 mg/mL
Infusion time: 15 minutes
IV Continuous Infusion YES, BP monitoring

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


  • 0.1-0.2 mg/kg/dose IM/IV Q 4-6 hours (max:20 mg/dose)
  • Up to 1.7-3.5 mg/kg/day divided in 4-6 doses


  • 10-20 mg/dose IM/IV Q 4-6 hours PRN (may increase to 40 mg/dose)


  • CrCl 10-50 mL/min: Administer Q 8 hours
  • CrCl <10 mL/min: Administer Q 8-18 hours (fast acetylators) and Q 12-24 hours (slow acetylators)
Potential hazards of parenteral administration: 
  • Hypotension (antidote norepinephrine or ephedrine - DO NOT use epinephrine; epinephrine may cause additive cardiac stimulation)
  • Early adverse effects (usually transient) are tachycardia, headache, palpitations, dizziness, nausea, vomiting, postural hypotension, anorexia, edema
  • Peripheral neuritis (paresthesias, numbness and tingling), pyridoxine may alleviate this reaction
  • Influenza-like syndrome, rheumatoid arthritis syndrome, lupus syndrome (after lengthy use)
  • Monitoring guidelines: monitor blood pressure immediately following the infusion, 15 min. post-infusion and one hour post infusion.  Patient should remain lying down for 30-60 minutes following the infusion.
  • Contraindicated in patients with angina pectoris, tachycardia, coronary artery disease
  • Use with caution in patients with recent coronary or cerebral ischemia
  • Hypotensive effects are enhanced by other antihypertensives

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