Table 1. Pharmacokinetics of different medications used in the management of hypertensive crises in the elderly.

Medication	Mechanism(s)	Dosage	Onset	Half-life
Nitroglycerin	Activation of guanylyl cyclase via NO	5 to 200 µg/min	2–5 min	1–4 min
Nitroprusside	Activation of guanylyl cyclase via NO	0.3 to 10 mcg/kg/min	< 2 min	–2 min
Nifedipine	1st generation dihydropyridine calcium-channel blocker	10 to 20 mg 3 times daily	–20 min	2.5–5 h
Nicardipine	1st generation dihydropyridine calcium-channel blocker	5–25 mg/h	5–15 min	4–6 h
Clevidipine	3rd generation dihydropyridine calcium-channel blocker	1–2 mg/h Increase every 10 min up to 16 mg/h	2–4 min	5–15 min
Labetalol	Selective α1-adrenergic receptor blocker andnonselective β-adrenergic blocker	200–400 mg per o.s. every 2–3 h	30–120 min	2–6 h
Esmolol	Beta1 receptor blocker	0.5–1 mg/kg loading dose.50–300 µg/kg/min infusion	60 s	20 min
Clonidine	Alpha2 adrenergic agonist and imidazoline I1 receptor agonist	500 µg/kg in bolus and 25–300 µg/kg/min	30 min	12–16 h
Fenoldopam	Dopamine type-1 receptor agonist	0.05–1.6 µg/Kg/ min	5–10 min	5 min
Hydralazine	Inhibition of calcium influx in vascular smooth muscle cells	20 mg initial bolus; 20–80 mg repeat boluses	5–15 min	3 h

NO: Nitric oxide.