Dosing and uses of Vazculep (phenylephrine)
Adult dosage forms and strengths
injectable solution
- 10mg/mL
Mild to Moderate Hypotension
Initial: 2-5 mg IM or SC; not to exceed 5 mg
Maintenance: 1-10 mg
Severe Hypotension/Shock
100-180 mcg increments IV bolus, THEn
40-60 mcg/min continuous IV infusion
Pediatric dosage forms and strengths
injectable solution
- 10mg/mL
Hypotension
5-20 mcg/kg IV bolus q10-15min PRN, Or
0.1-0.5 mcg/kg/min IV continuous infusion
Vazculep (phenylephrine) adverse (side) effects
Frequency not defined
Extravasation
Hypertension
Reflex bradycardia
Anxiety
Headache
Burning
Rebound congestion
Sneezing
Pulmonary edema
Metabolic acidosis
Decreased renal perfusion
Reduced urine output
Nausea
Gastric irritation
Warnings
Black box warnings
Physicians should completely familiarize themselves with complete contents of package insert prior to prescribing phenylephrine hydrochloride injection
Contraindications
Hypersensitivity to phenylephrine or sulfites
Severe hypertension
Ventricular tachycardia
Closed-angle glaucoma
Cautions
Cerebrovascular insufficiency
Cardiovascular disease
Hypertension
Diabetes mellitus
Thyroid disease
Prostatic hypertrophy
Geriatric patients
Pregnancy and lactation
Pregnancy category: C
Lactation: Safe
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Vazculep (phenylephrine)
Mechanism of action
Strong alpha effects resulting in increased peripheral vascular resistance and blood pressure; decreases cardiac output and renal perfusion
Absorption
Bioavailability: <38%
Onset: 10-15 min
Duration: 15 min
Peak plasma time: 0.75-2 hr
Distribution
Vdss: 184-543 L
Metabolism
Extensively metabolized in intestinal wall; moderately metabolized in liver
Metabolites: M-hydroxymandelic acid (inactive)
Elimination
Half-life: 2-3 hr (terminal phase)
Excretion: Urine (80-90%)
Administration
IV Compatibilities
Additive: Chloramphenicol, dobutamine, lidocaine, KCl, Na bicarB
Y-site: Amiodarone, amrinone, famotidine, haloperidoL
IV Preparation
10 mg in 250 mL D5W (40 mcg/mL); at 2-5 mL/min (80-200 mcg/min)
100-500 mg in 250 mL have been used
