Drug information of Tolazoline


Drug group:

A vasodilator that apparently has direct actions on blood vessels and also increases cardiac output. Tolazoline can interact to some degree with histamine, adrenergic, and cholinergic receptors, but the mechanisms of its therapeutic effects are not clear.

It is used in treatment of persistent pulmonary hypertension of the newborn. In some countries, this medicine may only be approved for veterinary use. Products containing tolazoline were withdrawn from the U.S. market in July 2002.

Mechanism of effect

Vasodilation by means of a direct effect on peripheral vascular smooth muscle and indirect effects produced, in part, by release of endogenous histamine; tolazoline has moderate alpha-adrenergic blocking activity and has histamine agonist activity. Tolazoline usually reduces pulmonary arterial pressure and vascular resistance.


Tolazoline is a pulmonary vasodilator indicated used to decrease pulmonary vascular resistance (PVR) in persistent pulmonary hypertension of the newborn (PPHN).


  • Half-life: Neonates: 3 to 10 hours; 
  • Onset of action: Within 30 minutes after initial dose. 
  • Elimination: Renal, primarily unchanged. 


Tolazoline hydrochloride injection: 100 mg/ml

Intravenous, 1 to 2 mg per kg of body weight via scalp vein over a five- to ten-minute period.

Intravenous infusion, 0.2 mg (200 mcg) per kg of body weight per hour. 

Drug contraindications

hypersensitivity to this drug


Studies have not been done in either humans or animals.

Points of recommendation

It is recommended that tolazoline be administered in an area with trained personnel and facilities necessary to provide pediatric or neonatal intensive care. Respiratory support should be available.

To achieve optimal dosage control, it is recommended that tolazoline be administered IV by means of an infusion pump or a similar device to allow precise adjustment of the flow rate.

Pretreatment with antacids may prevent gastrointestinal bleeding in infants.

Use of epinephrine or norepinephrine is not recommended because of the risk of a further decrease in blood pressure.

Pregnancy level


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