ANTENEX

What it is

ANTENEX is a benzodiazepine that exhibits anxiolytic, sedative, muscle relaxant and anticonvulsant effects. This is presumed to result from facilitating the action in the brain of gamma-aminobutyric acid (GABA), a naturally occurring inhibitory neurotransmitter.

Approved indications

— Management of anxiety disorders or for the short term relief of symptoms of anxiety. — Relief of acute agitation, tremor, impending or acute delirium tremens and hallucinosis in acute alcohol withdrawal. — Relief of reflex muscle spasms due to local trauma (injury, inflammation) to muscles, bones and joints. — Management of spasticity due to upper motor neuron lesions such as cerebral palsy and paraplegia, as well as in athetosis and stiff man syndrome. — Controlling status epilepticus and the spasms of tetanus. — Preoperative medication.

Dosing overview

The usual adult dose is 2 to 10 mg by intramuscular or intravenous injection repeated every three to four hours as required. The maximum adult dose should not exceed 30 mg over an eight hour period. Intravenous injections should be given into a large vessel, such as an antecubital vein, and the solution should be administered slowly at a rate not exceeding 5 mg per minute. Lower doses should be used in the elderly, those with impaired hepatic or renal function or debilitated patients, and these patients should be checked regularly at the start of treatment to minimise the dosage and/or frequency of administration to prevent overdose due to accumulation.

Key safety warnings

Concomitant use of ANTENEX with alcohol and/or with drugs, including opioids that have a depressive effect on the central nervous system should be avoided, as these agents can enhance the clinical effects and can possibly result in deep sedation, clinically significant respiratory and/or cardiovascular depression, coma, and death. These medications should either be eliminated or limit dosages and durations to the minimum required in the presence of ANTENEX. ANTENEX should be prescribed for short periods only (e.g. 2 to 4 weeks). Continuous long term use is not recommended. The use of benzodiazepines may lead to dependence, with the risk of dependence increasing with dose and duration of treatment. It is more pronounced in patients on long term therapy and/or high dosage and particularly so in predisposed patients with a history of alcohol or drug abuse. Extreme care must be used in administering injectable ANTENEX, particularly by the intravenous route, to the elderly, to very ill patients and to those with limited pulmonary reserve because of the possibility that apnoea and/or cardiac arrest may occur. Transient amnesia or memory impairment has been reported in association with the use of benzodiazepines. Anterograde amnesia may occur using therapeutic doses, the risk increasing at higher doses.

Contraindications

ANTENEX is contraindicated in patients with a known hypersensitivity to benzodiazepines or any of the excipients. It is contraindicated in patients with severe respiratory failure, or chronic obstructive airways disease with incipient respiratory failure. It should not be used as sole therapy in psychosis including primary depressive disorders. ANTENEX is contraindicated in patients with myasthenia gravis. The drug should not be administered intravenously to patients in shock, coma, patients with cardiac or respiratory insufficiency or those with acute alcoholic intoxication with depressed vital signs.

Key safety warnings

Since ANTENEX passes into breast milk, injectable ANTENEX should not be administered to breastfeeding mothers, or breastfeeding should be suspended if the product is to be given regularly. Sedation, amnesia, impaired concentration and impaired muscle function may adversely affect the ability to drive or operate machinery. Patients should be warned not to operate dangerous machinery or drive motor vehicles until completely recovered. Too rapid injection or the use of veins with too small a lumen carries the risk of syncope, apnoea, hypotension, bradycardia or cardiac or respiratory arrest and thrombophlebitis. Resuscitation equipment must be kept ready at all times. Intra-arterial injection must be carefully avoided on account of the danger of necrosis and extravasation must be strictly avoided because venous thrombosis, phlebitis, local irritation, swelling, or less frequently, vascular changes may occur.