0071643192.pdf

TOXICOLOGY

DIFFERENTIAL

β-Blockers, calcium channel blockers, digoxin

DIAGNOSIS

■ Usually obvious from patient’s history

■ Should be considered in the differential of any patient with bradycardia

and hypotension

TREATMENT

■ Supportive care

■ Activated charcoal with protected airway if large and recent ingestion

■ Bradycardia and hypotension typically respond to IV fluids, but may

require atropine and/or vasopressors.

■ Naloxone has been reported to reverse some of the sedation, but a mecha-

nism and evidence are lacking.

Other Antihypertensive Agents

Table 6.16 lists other hypertensive agents that may present with acute toxicity

in overdose.

These drugs usually will cause symptoms, but they are rarely as life-threatening

as a single drug ingestion.

DIAGNOSIS

■ Usually obvious from patient’s history

TREATMENT

■ Supportive care with IV fluids and vasopressors (if needed) is usually

sufficient.

TABLE 6.16. Toxicity From Other Hypertensive Agents

ANTIHYPERTENSIVEAGENT MECHANISM/TOXICITY SYMPTOMS/EXAM

Hydralazine Direct acting vasodilator Hypotension

Tachycardia

Hypokalemia

Minoxidil Inhibits Ca++uptake into cells → Hypotension

vasodilation Tachycardia

Methyldopa Metabolite stimulates central Hypotension

α 2 -receptors→↓sympathetic Miosis

output. Sedation

Respiratory depression

Guanethidine Decreases norepinephrine Hypotension

Guanadrel release from nerve terminals

Doxazocin Selective α 1 -receptor Hypotension

Prazosin blocker →↓PVR. Tachycardia

Terazosin Dizziness/syncope