through bronchodilation. Because it affects three different receptors, it
lacks selectivity.
Alpha-adrenergic blockers inhibit the response at the alpha-adrenergic recep-
tor sites. There are two types of alpha-adrenergic blockers: selective and nonse-
lective blockers. Both types decrease symptoms of benign prostatic hypertrophy
(BPH) (enlarged prostate) and promote vasodilation and treat peripheral vascu-
lar disease such as Raynaud’s disease.
Doxazosin (Cardura) is a selective alpha 1 -blocker and phentolamine
(Regitine) is a nonselective alpha adrenergic blocker. Both can be used to treat
hypertension.
However, alpha-adrenergic blockers can cause orthostatic hypotension (drop
in blood pressure when an individual stands up), dizziness, and reflex tachycar-
dia. They are not as frequently prescribed as beta-blockers.
Beta-adrenergic blockers (see chart)—also known beta blockers—decrease
heart rate and decrease blood pressure resulting in bronchoconstriction. Therefore,
beta-adrenergic blockers should be used with caution for patient’s who have
COPD or asthma.
CHAPTER 15 Nervous System Drugs^285
Other Adrenergics
Ephedrine HCl PO 25–50 mg tid/qid; SC/IM: 25–50 mg; IV: 10–25 mg PRN;
(alpha 1 , beta 1 , beta 2 ) maximum dose 150 mg/24 hr; effective for relief of hay fever,
sinusitis, and allergic rhinitis; may be used for treating mild
cases of asthma; Pregnancy category C: PB UK; half life
3–6 hours.
Norepinephrine bitartrate Potent vasoconstrictor; IV: 4 mg in 250–500 mL of D 5 Wor
(Levophed) (alpha 1 , beta 1 ): NSS infused initially 8–12 g/min; then 4 g/min; titrated
according to blood pressure; Pregnancy category CD PB: UK;
half life: UK.
Metaraminol bitartrate V/Inf: 15–100 mg in 500 mg D 5 W at a rate adjusted according
(Aramine) (alpha 1 , beta 1 ) to blood pressure; Pregnancy category C; PB UK; half life UK.
Dobutamine HCl To treat cardiac decompensation due to depressed myocardial
(Dobutrex) (beta 1 ) contractility which may result from organic heart disease,
cardiac surgery. IV: 2.5–20 g/kg/min initially; increase dose
gradually; maximum dose of 40 g/kg/min. Pregnancy
category: C; PBUK; half life 2 min.
Dopamine HCl (Intropin) 1–5 g/kg/min initially; gradually increase 5–10 g/kg/min
(alpha 1 , beta 1 ) IV/Inf to a maximum of 50 g/kg/min; it does not decrease renal
function in doses <5 g/kg/min. Pregnancy category C;
PB: UK; half life 2 min.