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BENZODIAZEPINES. Mechanism of action. It interacts with specific receptors in the CNS, particularly in the cerebral cortex. Benzodiazepine-receptor binding enhances the inhibitory effects of various neurotransmitters. ( GABA Facilitatory)
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Mechanism of action • It interacts with specific receptors in the CNS, particularly in the cerebral cortex. • Benzodiazepine-receptor binding enhances the inhibitory effects of various neurotransmitters. ( GABA Facilitatory) • Flumazenil (an imidazolebenzodiazepine) is a specific benzodiazepine-receptor antagonist that reverses most of the CNS effects of benzodiazepines. (Dose: 0.2-0.5mg IV to a maximum of 3mg)
Diazepam • It is a colorless crystalline compound, insoluble in water and has a molecular weight of 284.74. • Each mL contains 5 mg diazepam compounded with 40% propylene glycol, 10% ethyl alcohol, 5% sodium benzoate and benzoic acid as buffers, and 1.5% benzyl alcohol as preservative.
Indications • Diazepam is indicated for the management of anxiety disorders or for the short-term relief of the symptoms of anxiety. • In acutealcohol withdrawal. • Diazepam Injection is a useful adjunct in status epilepticus and severe recurrent convulsive seizures. • Diazepam is a useful premedication (the IM route is preferred) for relief of anxiety and tension in patients who are to undergo surgical procedures. • To prevent hallucination caused by Ketmaine.
DOSAGE AND ADMINISTRATION • Dosage should be individualized for maximum beneficial effect. The usual recommended dose in adults ranges from 2 mg to 20 mg IM or IV, depending on the indication and its severity. • Anxiety Disorders and Symptoms of Anxiety: 2 mg to 5 mg, IM or IV • Acute Alcohol Withdrawal • The usual dose is 10 mg---- 3 or 4 times during the first 24 hours, then 5 mg---- 3 or 4 times daily as needed. • Relief of Muscle Spasm • The usual dose is 2mg to 10 mg----- 3 or 4 times daily. • Convulsive Disorders • The usual dose is 2 mg to 10 mg------- 2 to 4 times daily
Systemic Effects • CNS: Mainly acts on RAS and amygdala ( limbic system) producing sedation, anxiolysis and amnesia. Also acts on medulla producing muscle relaxation and on cerebellum producing ataxia. • No any analgesic effects. • Produce Muscle relaxation by acting on medullary and spinal cord (central action) and not at neuromuscular junction. • Reduces cerebral metabolic rate, brain oxygen consumption and Intracranial pressure.
Respiratory system: • At higher dose cause respiratory depression and may lead to death. • It is maximum seen with midazolam. • Cardiovascular System • Minimal reduction in blood pressure , heart rate and cardiac output. • Hypotension is maximum with midazolam.
Metabolism • Metabolized in Liver. • The major active metabolite of diazepam is des-methyl diazepam. • Metabolites are excreted in Gut and Urine.
Side effects • Fatigue and ataxia; venous thrombosis and phlebitis at the site of injection • CNS: confusion, depression, dysarthria, headache, slurred speech, syncope, tremor, vertigo. • GI: constipation, nausea. • GU: incontinence ,libido, urinary retention. • Cardiovascular: bradycardia, cardiovascular collapse, hypotension. • OTHERS : blurred vision, diplopia, nystagmus,urticaria, skin rash, jaundice.
Contraindications and Precautions • Valium Injection is contraindicated in patients with a known hypersensitivity to this drug. • Valium Injection should not be administered to patients in shock, coma. • Should be used with precautions in patients with pulmonary and cardiovascular diseases. • Usage in Pregnancy: An increased risk of congenital malformations associated with the use of diazepam during the first trimester of pregnancy has been suggested in several studies.