OVERDOSE
Experience with doxazosin mesylate overdosage is limited.
Two adolescents who each intentionally ingested 40 mg
doxazosin mesylate with diclofenac or paracetamol, were
treated with gastric lavage with activated charcoal and
made full recoveries. A two-year-old child who accidentally
ingested 4 mg doxazosin mesylate was treated with gastric
lavage and remained normotensive during the five-hour
emergency room observation period. A six-month-old child
accidentally received a crushed 1 mg tablet of doxazosin
mesylate and was reported to have been drowsy. A 32-year-old
female with chronic renal failure, epilepsy and depression
intentionally ingested 60 mg doxazosin mesylate (blood
level 0.9 mg/ml; normal values in hypertensives=0.02 mcg/ml);
death was attributed to a grand mal seizure resulting
from hypotension. A 39-year-old female who ingested 70
mg doxazosin mesylate, alcohol and Dalmane (flurazepam)
developed hypotension which responded to fluid therapy.
The oral LD50 of doxazosin is greater than 1000 mg/kg
in mice and rats. The most likely manifestation of overdosage
would be hypotension, for which the usual treatment would
be intravenous infusion of fluid. As doxazosin is highly
protein bound, dialysis would not be indicated.
CONTRAINDICATIONS
Doxazosin mesylate is contraindicated in patients with a
known sensitivity to quinazolines (e.g., prazosin, terazosin).
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