Pharmacology Of Edrophonium

Indication	For the differential diagnosis of myasthenia gravis and as an adjunct in the evaluation of treatment requirements in this disease. It may also be used for evaluating emergency treatment in myasthenic crises.
Pharmacodynamics	Edrophonium is a short and rapid-acting anticholinesterase drug. Its effect is manifest within 30 to 60 seconds after injection and lasts an average of 10 minutes. Edrophonium's pharmacologic action is due primarily to the inhibition or inactivation of acetylcholinesterase at sites of cholinergic transmission. Muscarinic receptors are found throughout the body, especially on muscle. Stimulation of these receptors causes to muscle contraction. In myasthenia gravis the body's immune system destroys many of the muscarinic receptors, so that the muscle becomes less responsive to nervous stimulation. Edrophonium chloride increases the amount of acetylcholine at the nerve endings. Increased levels of acetyl choline allow the remaining receptors to function more efficiently.
Mechanism of action	Edrophonium works by prolonging the action acetylcholine, which is found naturally in the body. It does this by inhibiting the action of the enzyme acetylcholinesterase. Acetylcholine stimulates nicotinic and muscarinic receptors. When stimulated, these receptors have a range of effects.
Absorption	Rapidly absorbed.
Volume of distribution	1.6±0.4 L/kg [Adults] 2.2±1.5 L/kg [Children (0.08-10 yrs)] 1.8±1.2 L/kg [Elderly (65-75 yrs)]
Protein binding	Not Available
Metabolism	Not Available
Route of elimination	Edrophonium is primarily renally excreted with 67% of the dose appearing in the urine. Hepatic metabolism and biliary excretion have also been demonstrated in animals
Half life	Distribution half-life is 7 to 12 minutes. Elimination half-life is 33 to 110 minutes.
Clearance	6.8 +/- 2. mL/kg/min [Adults] 6.4 +/- 3.9 mL/kg/min [Children (0.08-10 yrs)] 2.9 +/- 1.9 mL/kg/min [Elderly (65-75 yrs)]
Toxicity	With drugs of this type, muscarine-like symptoms (nausea, vomiting, diarrhea, sweating, increased bronchial and salivary secretions and bradycardia) often appear with overdosage (cholinergic crisis).