TENSILON TEST

TENSILON AMPOULES 10mg

COMPOSITION:

Each vial contains 10mg of edrophonium chloride compounded with 0.2% sodium sulphite as preservative, buffered with sodium citrate and citric acid and pH adjusted to approximately 5.

PHARMACOLOGICAL ACTION:

Tensilon (edrophonium chloride) is a fast acting anticholinesterase used for diagnosis of myasthenia gravis.  Its pharmacological action is due primarily to the inhibition or inactivation of acetylcholinesterase at sites of cholinergic transmission.  Its effect is manifested within 30-60seconds after injection and lasts an average of 10 minutes.

INDICATIONS:

For the diagnosis of myasthenia gravis and as adjunct in the evaluation of treatment requirements in this disease.  It may also be used for evaluating emergency treatment of myasthenic crisis.

Also useful whenever a curare antagonist is needed to reverse the neuromuscular block produced by curare, tubocurarine, gallamine triethiodide or dimethyl-tubocurarine.  It is not effective against decmethonium bromide and succinylcholine.  It may be used adjunctively in the treatment of respiratory depression in curare overdosage.

CONTRAINDICATIONS

It is not recommended as a maintenance therapy in myasthenia gravis due to its brief duration of action.

Known hypersensitivity to anticholinesterase agents, mechanical intestinal or urinary obstruction.

Should not be used in conjunction with depolarising muscle relaxants such as Suxamethonium.  It should not used during cyclopropane or halothane anaesthesia, although it may be used after withdrawal of these agents.

Large doses by mouth should be avoided in conditions where there may be increased absorption from the GIT.

ADMINISTRATION:

1.      Mix  1ml of Tensilon with 9 mls of sterile H2O to constitute a 1mg/ml solution.

2.      Pre-dose with 600 mg Atropine. Have further 600 mg drawn up.

3.      Insert butterfly needle into vein.

4.      Monitor patient’s pulse (oximeter or cardiac monitor )

5.      Administer 1-2mg of Tensilon as a test dose.

6.      If after 45 seconds there are no side effects (bradycardia, diaphoresis, or abdominal cramps) or evidence of cholinergic weakness, the remaining 8mg of Tensilon is administered.

7.      In most patients with myasthenia muscle function will improve dramatically.  The most dramatic response will usually be seen in patients with ocular symptoms.

8.      Some muscle twitching may be seen and is an indication of adequate test dose. This is usually most apparent in the periorbital muscles.

*In using Tensilon to evaluate myasthenic weakness, the physician may use a placebo such as 1ml of normal saline.  A placebo can be helpful in the differential diagnosis because there are many varied causes of weakness, including psychogenic causes.

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