Drug Interaction:
VASSOPRESSORS USED IN SHOCK- includes-
Inotropic effects -
Isoproternol, Dobutamine, Dopamine, Ephinephrine,
Mixed effects-
Norephinephrine, Ephedrine, Mephentermine
Pressors effects-
Metaraminol
Methoxamine
Phenylephrine
Interacting drugs- summary
+Methoxamine-
Bretylium
Bretylium may potentiate the action of vasopressors on adrenergic
receptors, possibly by resulting in arrhythmias
Guanethidine
guanethidine may increase the pressor response of the direct-acting
vasopressors, possibly resulting in severe hypertension
Halogenated hydrocarbon anesthetics
halogenated hydrocarbon anesthetics may sensitise the effects of
catecholamines. Use of vasopressors may lead to serious
arrthythmias, use with extreme caution
Oxytocic drugs
if vasopressor drugsare used in obstertics to correct hyoptension
or added to local anesthetic solution, some oxytocic drugs may
cause severe persistent hypertension
Tricyclic antidep
the vasopressor response of the mixed-acting vasopressors may
be decreased by tricyclic antidepressants, a higher dose of the
sympathomimetic may be necessary
Indication:
Acute hypotensive state.
VASSOPRESSORS USED IN SHOCK- includes-
Inotropic effects -
Isoproternol, Dobutamine, Dopamine, Ephinephrine,
Mixed effects-
Norephinephrine, Ephedrine, Mephentermine
Pressors effects-
Metaraminol
Methoxamine
Phenylephrine
Adverse Reaction:
Intergumentary- Sweating, pilomotor response.
Cardiovascular- Excessive blood pressure elevation, fetal bradycardia, ventricular ectopic beats.
GI- Nausea, vomiting.
CNS- Headache, anxiety.
GU- Uterine hypertonus, fetal bradycardia, urinary urgency.
Drug/test interactons-
Methoxamine may increase plasma cortisol and ACTH levels . Excercise caution when interpreting plasma cortisol and ACTH levels in patients receiving methoxanine
Contra-Indications:
Severe hypertension, hypesens to the drug
Special precautions:
Extravasation- use large veins for infusion. Use with care in patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease or severe arteriosclerosis. Sulfite sensitivity- allergic reaction
Hypovalemia- use is not a substitute for the replacement of blood, plasma, fluids, and electrolytes, which should be restored promptly when loss has occurred.
Use with care - in patients with hypothyroidism, bradycardia, partial herat block, myocardial disease or severe artriosclerosis
Warnings-
Pregnancy- use during pregnancy only of the potential benefit justifies the potential risk to the fetus.
Lactation- excercise cautin when administering methoxamine to a nursing woman.
Children- safety and efficacy inchildren have not been established.
Dosages/ Overdosage Etc:
Indications:
Acute hypotensive state.
Dosage:
May be given IM, SC or IV- recommended dose is 2 to 10mg
Overdosage-
Symptoms
Undesirably high blood pressure or excessive bradycardia.
Clinically significant elevations of blood pressure may be reversed with an alpha- adrenergic blocking agent eg phentolamine
Treatment
1. Bradycardia may be abolished with atropine.
Missed dose-
1. If you are using this medicine regularly and you miss a dose, use it as soon as possible.
2. Then use the remaining dose fotbthat day at regularly spaced intervals.
3. Do not double doses.
Pharmacology/ Pharmacokinetics:
Pharmacology:
A vasopressor that produces aprompt and prolonged rise in blood pressure by increasing
peripheral resistence. Specially useful for maintaining blood pressure during operation.
Pharmacokinetics:
Following IV admin of methoxamine the peak pressor effect occurs withib 0.5 to 2 minutes. The duration of the pressor efect following asingle IV dose of 2 to 4 mg was 10 to 15 minutes
Pregnancy and lactation:
Pregnancy:
Use during pregnancy only if the potential benefit justifies the potential risk to the fetus
Lactation:
Excercise caution when administering methoxamine to a nursing woman.
Children-
Safety and efficacy inchildren have not been established.
