Diazepam (marketed under brand names Valium®, Seduxen® and Apozepam®) is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative, skeletal muscle relaxant and amnestic properties. Diazepam is a core medicine in the World Health Organization's "Essential Drugs List", which is a list of minimum medical needs for a basic health care system. Diazepam is used to treat a wide range of conditions and is one of the most frequently prescribed benzodiazepines.
Diazepam was the second benzodiazepine to be invented by Leo Sternbach, and was approved for use in 1963. It is five times more potent than its predecessor, chlordiazepoxide, which it quickly surpassed in terms of sales. After this initial success, other pharmaceutical companies began to introduce other benzodiazepine derivatives.
The benzodiazepines gained popularity among medical professionals as an improvement upon barbiturates, which have a comparatively narrow therapeutic index, and are far more sedating at therapeutic doses. The benzodiazepines are also far less dangerous; death rarely results from diazepam overdose, except in cases where it is consumed with large amounts of other depressants (such as alcohol or other sedatives).
Diazepam was the top-selling pharmaceutical in the United States from 1969 to 1982, with peak sales in 1978 of 2.3 billion pills.
Over the years, physicians, psychiatrists and neurologists have discovered many new off-label uses for diazepam, such as treatment of spastic paresis and palliative treatment of stiff-person syndrome.[
Diazepam occurs as solid white or yellow crystals and has a melting point of 131.5 to 134.5°C. It is odorless, and has a slightly bitter taste. The British Pharmacopoeia lists diazepam as being very slightly soluble in water, soluble in alcohol and freely soluble in chloroform. The United States Pharmacopoeia lists diazepam as soluble 1 in 16 of ethyl alcohol, 1 in 2 of chloroform, 1 in 39 of ether, and practically insoluble in water. The pH of diazepam is neutral (i.e. 7). Diazepam has a shelf-life of 5 years for oral tablets and 3 years for IV/IM solution.
Diazepam should be stored at room temperature (15°-30°C). The solution for parenteral injection should be protected from light and kept from freezing. The oral forms should be stored in air-tight containers and protected from light.
Diazepam may adsorb into plastic, and therefore diazepam solution should not be stored in plastic bottles or syringes. It may also adsorb into plastic bags and tubing used for intervenous infusions. Absorption appears to be dependent on several factors such as temperature, concentration, flow rates and tube length. Do not administer diazepam if a precipitate has formed and will not dissolve.
In animal models, diazepam appears to act on areas of the limbic system, thalamus and hypothalamus, inducing anxiolytic effects. Its actions are due to the enhancement of GABA activity.
Diazepam binds to specific benzodiazepine sites on subunits of GABAA receptors, which are distinctly different than those which endogenous GABA molecules bind to.
Due to the role of diazepam as a positive allosteric modulator of GABA, when it binds to benzodiazepine receptors it causes inhibitory effects. This arises from the hyperpolarization of the postsynaptic membrane, due to the control exerted over negative chloride ions by GABAA receptors.
In humans, tolerance to the sedative effects may develop within several weeks, but tolerance to the anxiolytic effects usually does not develop. Lorazepam, clonazepam and alprazolam show stronger anxiolytic effects compared to diazepam, but carry a higher risk of misuse, abuse, tolerance and dependence.
Diazepam can be administered orally, intravenously, intramuscularly, or as a suppository.
With oral administration, diazepam is rapidly absorbed and has a fast onset of action. Peak plasma levels are achieved 30 minutes to 2 hours after oral administration.
With intramuscular administration, absorption is slow, erratic and incomplete.
Diazepam is highly lipid-soluble, and is widely distributed throughout the body after administration. It easily crosses both the blood-brain barrier and the placenta, and is excreted into breast milk. After absorbtion, diazepam is redistributed into muscle and adipose tissue. Continual daily doses of diazepam will quickly build up to a high concentration in the body (mainly in adipose tissue), which will be far in excess of the actual dose for any given day.
Diazepam is metabolised in the liver via the cytochrome P450 enzyme system. It has a biphasic half-life of 1-2 and 2-5 days, and has several pharmacologically active metabolites. The main active metabolite of diazepam is desmethyldiazepam (also known as nordazepam). Diazepam's other active metabolites include temazepam and oxazepam. These metabolites are conjugated with glucuronide, and are excreted primarily in the urine. Because of these active metabolites, the serum values of diazepam alone are not useful in predicting the effects of the drug.
Diazepam has a half-life (t1/2α) of 20-50 hours, and desmethyldiazepam has a half-life of 30-200 hours.
Most of the drug is metabolised; very little diazepam is excreted unchanged.
In humans, the protein binding of diazepam is around 98.5%.
Diazepam is mainly used to treat anxiety, insomnia, and symptoms of acute alcohol or opiate withdrawal. It is also used as a premedication for inducing sedation, anxiolysis or amnesia prior to certain medical procedures (e.g. endoscopy).
Diazepam is rarely used as a primary drug for the long-term treatment of epilepsy. This is due to the fact that tolerance to the anticonvulsant effects of diazepam usually develops within 6 to 12 months of treatment, effectively rendering it useless for this purpose.
Diazepam has a broad spectrum of indications (most of which are off-label), including:
Treatment of anxiety, panic attacks, and states of agitation
Treatment of status epilepticus, adjunctive treatment of other forms of epilepsy
Treatment of the symptoms of alcohol and opiate withdrawal
Short-term treatment of insomnia
Treatment of tetanus, together with other measures of intensive-treatment
Initial management of mania, together with firstline drugs like lithium, valproate or neuroleptics
Adjunctive treatment (with antidepressants) of depression with symptoms of anxiety
Adjunctive treatment (with neuroleptics), in patients who develop early extrapyramidal side-effects
Adjunctive treatment of painful muscle conditions
Adjunctive treatment of spastic muscular paresis (para-/tetraplegia) caused by cerebral or spinal cord conditions such as stroke, multiple sclerosis, spinal cord injury (long-term treatment is coupled with other rehabilitative measures)
Palliative treatment of stiff person syndrome
Pre-/postoperative sedation, anxiolysis and/or amnesia (e.g. before endoscopic or surgical procedures)
Treatment of overdosage with hallucinogens or CNS stimulants
Adjunctive treatment of drug-induced seizures, resulting from exposure to sarin, VX, soman (or other organophosphate poisons), lindane, chloroquine, physostigmine, or pyrethroids
Occasionally, diazepam is used by military and paramilitary snipers to relax muscles and slow breathing for increased firing accuracy
Diazepam is very useful as short term sedative and anxiolytic for cats and dogs. It can also be used for preoperative sedation of cats and dogs and as an anticonvulsive suitable for short-term and long-term treatment, if sedation is tolerated. To terminate status epilepticus in cats, as much as 5mg is administered rectally or intervenously, repeating as needed
Dosages should be determined on an individual basis, depending upon the condition to be treated, the severity of symptoms, the body weight of the patient, and any comorbid conditions the patient may have.
Elderly patients and those with liver disorders experience decreased metabolism of diazepam; therefore the dosage for these patients should be reduced. General guidelines for this group of patients: initial doses of 2mg to 2.5mg, 1 or 2 times daily; increase gradually as required/tolerated.
Adult dosage recommendations
Insomnia - Up to 30mg orally, as a single dose, at bedtime.
Anxiety/panic attacks - Dosage differs depending upon severity of symptoms. For panic attacks, diazepam is taken "as needed".
Oral - 2mg to 10mg oral, 2 to 4 times daily.
IV/IM - 2mg to 10mg. Repeat in 3 to 4 hours, if necessary.
Pre-/postoperative sedation - If other premedications are used, they must be administered separately.
Oral - Up to 20mg as a single dose.
IV/IM - 2mg to 10mg, repeated at intervals of at least 5 to 10 minutes, until adequate sedation and/or anxiolysis is achieved.
Oral - 2mg to 10mg, 2 to 4 times daily.
IV/IM - 5mg to 10mg. May be repeated every 5 to 10 minutes until termination of seizures. Maximum dose of 40mg to 60mg can be used; if this dose is ineffective, other anticonvulsant drug therapy should be instituted.
Rectal solution - 10mg as a single dose. May be repeated after 5 minutes, if necessary. The oral solution can also be administered rectally.
Painful muscle conditions or muscle spasms
Oral - Up to 15mg daily, in divided doses. In severe spasticity associated with cerebral palsy, doses may be increased gradually up to 60mg daily.
IV/IM - 5mg to 10mg initially, then 5mg to 10mg in 3 to 4 hours, if necessary.
Tetanus - 100 to 300µg/kg intravenously, repeated every 1 to 4 hours.
Spastic paresis - Usually starting with 3 times daily 2mg, increasing to up to 3 times 20mg in slow increments, taking care to avoid ataxia.
Alcohol/opioid withdrawal - For symptomatic relief of agitation, tremor, delirium tremens and hallucinosis.
Oral - 10mg, 3 or 4 times during the first 24 hours. Reduce to 5mg, 3 or 4 times a day, or as needed.
IV/IM - 10mg initially, 5mg to 10mg in 3 to 4 hours, if necessary.
Initial treatment of mania - 30 to 40mg daily oral or rectal, rarely more.
Overdosage with hallucinogens/CNS stimulants - Normally a single intravenous dose of 10 to 20mg is sufficient.
Adjunctive treatment of depression - Usually 10 to 30mg daily oral, the greater part of the dose given at bedtime. The doses should be decreased and the medication stopped as soon as the clinical situation allows.
Adjunctive treatment of extrapyramidal side-effects - Depends on the individual. Effective dose(s) unknown. Do not administer for more than 4 weeks.
Cardioversion - To relieve anxiety/tension and to reduce recall of procedure. 5mg to 15mg IV, 5 to 10 minutes prior to the procedure.
Pediatric dosage recommendations
Patients over 6 months of age:
Initiate therapy with the lowest effective dose.
Oral: Initial dose of 40 to 200µg/kg of bodyweight. Can be repeated as tolerated, up to 4 times daily.
Rectal suppository: 40 to 200µg/kg of bodyweight, which can be repeated as tolerated up to 4 times daily.
Sedation or muscle relaxation
IV/IM - 200µg/kg of bodyweight.
IV/IM - 200 to 300µg/kg of bodyweight. May be repeated after 5 to 10 minutes, if required.
Rectal solution - 5mg (for patients 1 to 3 years of age); repeat after 5 to 10 minutes, if necessary.
Patients 30 days to 5 years of age - 1mg to 2mg IV/IM, slowly; repeat every 3 to 4 hours, as necessary.
Patients 5 years of age or older - 5mg to 10mg IV/IM, slowly; repeat every 3 to 4 hours, as necessary.
Patients 30 days to 5 years of age - 0.2mg to 0.5mg IV/IM, slowly, every 2 to 5 minutes. Maximum dose of 5mg.
Patients 5 years of age or older - 1mg IV/IM, slowly, every 2 to 5 minutes. Maximum of dose of 10mg. Repeat in 2 to 4 hours, if necessary.
Patients under 6 months of age:
Diazepam should not be given to children under 6 months of age.
Diazepam is supplied in the following forms:
For oral administration:
Tablets - 2mg, 5mg, 10mg. Generic versions available.
Capsules, time-release - 15mg (marketed by Roche as Valrelease®)
Liquid solution - 1mg/ml in 500ml containers and unit-dose (5mg & 10mg); 5mg/ml in 30 ml dropper bottle (marketed by Roxane as Diazepam Intensol®)
For parenteral administration:
Solution for IV/IM injection - 5mg/ml. 2ml ampoules and syringes; 1ml, 2ml, 10ml vials; 2 ml Tel-E-Ject; also contains 40% propylene glycol, 10% ethyl alcohol, 5% sodium benzoate and benzoic acid as buffers, and 1.5% benzyl alcohol as a preservative.
For rectal administration:
Suppositories - 5mg and 10mg
Diazepam has a range of side effects which are common to most benzodiazepines. Most common side effects include:
Impaired motor function
Anterograde amnesia (especially pronounced in higher doses)
Rare paradoxical side effects include: nervousness, irritability, insomnia, muscle cramps, and in extreme cases, even rage and violence. If these side effects are present, diazepam treatment should be immediately terminated.
Up to 30% of individuals treated on a long-term basis develop a form of dependence known as "low-dose-dependence". These patients do not develop a tolerance, and do not need increasingly large doses to experience the euphoric side effects of the drug.
Diazepam may impair the ability to drive vehicles or operate machinery. The impairment is worsened by consumption of alcohol, because both act as central nervous system depressants. During the course of therapy tolerance to the sedative effects usually develops.
Patients with severe attacks of apnea during sleep may suffer respiratory depression (hypoventilation) leading to respiratory arrest and death.
Organic changes such as leukopenia and liver-damage of the cholostatic type with or without jaundice (icterus) have been observed in a few cases.
If diazepam is to be administered concomitantly with other drugs, attention should be paid to the possible pharmacological interactions. Particular care should be taken with drugs that enhance the effects of diazepam, such as barbiturates, phenothiazines, narcotics and antidepressants.
Diazepam does not increase or decrease hepatic enzyme activity, and does not alter the metabolism of other compounds. There is no evidence which would suggest that diazepam alters its own metabolism with chronic administration.
Agents which have an effect on hepatic cytochrome P450 pathways or conjugation can alter the rate of diazepam metabolism. These interactions would be expected to be most significant with long-term diazepam therapy, and their clinical significance is variable.
Diazepam increases the central depressive effects of alcohol, other hypnotics/sedatives (e.g. barbiturates), narcotics, and other muscle relaxants. The euphoriant effects of opioids may be increased, leading to increased risk of psychological dependence.
Cimetidine, omeprazole, ketoconazole, itraconazole, disulfiram, fluvoxamine, isoniazid, erythromycin, probenicid, propranolol, imipramine, ciprofloxacin, fluoxetine and valproic acid prolong the action of diazepam by inhibiting its elimination.
Oral contraceptives ("the pill") significantly decrease the elimination of desmethyldiazepam, a major metabolite of diazepam.
Rifampin, phenytoin, carbamazepine and phenobarbital increase the metabolism of diazepam, thus decreasing drug levels and effects.
Nefazodone can cause increased blood levels of benzodiazepines.
Cisapride may enhance the absorption, and therefore the sedative activity, of diazepam.
Small doses of theophylline may inhibit the action of diazepam.
Diazepam may block the action of levodopa (used in the treatment of Parkinson's Disease).
Diazepam may alter digoxin serum concentrations.
Other drugs that may have interactions with diazepam include: Antipsychotics (e.g. chlorpromazine), MAO inhibitors, ranitidine.
Smoking tobacco can enhance the elimination of diazepam and decrease its action.
Foods that acidify the urine can lead to faster absorbtion and elimination or diazepam, reducing drug levels and activity.
Foods that alkalinize the urine can lead to slower absorbtion and elimination or diazepam, increasing drug levels and activity.
There are conflicting reports as to whether food in general has any effects on the absorption and activity of orally administered diazepam.
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