dogenous catechol amines norepinephr ine 【Therapeutic Uses】 Limited clinical value Shock 【Precautions】 Necrosis and sloughing at the site of intravenous injection owing the extravasation of the drug. Impaired circulation at injection sites may be relieved by infi ltrating the area with phentolamine,an a receptor antagoni st.Endogenous catecholamines norepinephrine 【Therapeutic Uses】 Limited clinical value Shock 【 Precautions 】 Necrosis and sloughing at the site of intravenous injection owing the extravasation of the drug. Impaired circulation at injection sites may be relieved by infiltrating the area with phentolamine, anαreceptor antagonist