CAs are absorbed from the intestine but are rapidly degraded by MAO and COMT present in the intestinal wall and liver. They are thus orally inactive.
ADMINISTRATION AND PREPARATIONS
CAs
are absorbed from the intestine but are rapidly degraded by MAO and COMT
present in the intestinal wall and liver. They are thus orally inactive.
1. Adrenaline
(Epinephrine) For systemic action,
0.2–0.5 mg s.c., i.m.,
action lasts ½ to 2 hrs.
ADRENALINE 1 mg/ml
inj.
As
local vasoconstrictor, 1 in 200,000 to 1 in 100,000 added to lidocaine; in XYLOCAINE with ADRENALINE: lidocaine
21.3 mg + adrenaline 0.005 mg/ml inj; 30 ml vial.
2.
Noradrenaline
(Norepinephrine,
levarterenol) 2–4 μg/min i.v. infusion; local tissue necrosis occurs if the
solution extravasates; do not mix with NaHCO3 in the same bottle
(rapid oxidation occurs); action starts declining within 5 min of discontinuing
infusion. It is rarely used now as a pressor agent. ADRENOR, NORAD,
VASCUE, NOR-DRIN 2 mg (base)/2 ml amp.
3.
Isoprenaline
(Isoproterenol) 20 mg sublingual, 1–2
mg i.m., 5–10 μg/min i.v. infusion;
action lasts 1–3 hrs. It is occasionally used to maintain idioventricular rate
till pacemaker is implanted. For bronchial asthma, it has been superseded by
selective β2 agonists. ISOPRIN 4 mg/2 ml inj,
NEOEPININE 20 mg sublingual tablets.
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