| [Edit]
Diazepam (), marketed under brand names Valium, Stesolid, Seduxen, Bosaurin, Diapam, Antenex and Apozepam)• is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative, skeletal muscle relaxant and amnestic properties. This makes it a useful drug for treating anxiety, insomnia, seizures, alcohol withdrawal, and muscle spasms. It is also used before certain medical procedures (such as endoscopies) to reduce tension and anxiety, and in some surgical procedures to induce amnesia.••
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.
top
Benzodiazepine
Diazepam is a benzodiazepine that binds to a specific subunit on the GABAA receptor at a site that is distinct from the endogenous GABA molecule.•••
top
History
Diazepam was the second benzodiazepine to be invented by Leo Sternbach of Hoffmann-La Roche, 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.• In 1966, The Rolling Stones released the song "Mother's Little Helper", which is about a mother needing the "little yellow pill" to get through the day.•
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 is also found in nature. Several plants, such as potato and wheat, contain trace amounts of naturally occurring diazepam and other benzodiazepines.•
top
Pharmacokinetics
Diazepam can be administered orally, intravenously, intramuscularly, or as a suppository..
When diazepam is administered orally, it is rapidly absorbed and has a fast onset of action. The onset of action is 1-5 minutes for IV administration and 15-30 minutes for IM administration. The duration of the diazepam's main pharmacological effects is 15 minutes to 1 hour for both routes of administration.
Peak plasma levels are achieved 30 minutes to 2 hours after oral administration. When diazepam is administered as an intramuscular injection, 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 absorption, 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 or nordiazepam). 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%.
top
Indications
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 the symptoms of alcohol and opiate withdrawal
Treatment of tetanus, together with other measures of intensive-treatment
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)
Pre-/postoperative sedation, anxiolysis and/or amnesia (e.g. before endoscopic or surgical procedures)
Used in the treatment for irritable bowel syndrome. [Neurological Encyclopedia. http://www.answers.com/diazepam ]
top
Veterinary uses
Diazepam is used as a short term sedative and anxiolytic for cats and dogs. It is also used for short-term treatment of seizures in dogs and short-term and long-term treatment of seizures in cats. For emergent treatment of seizures, the typical dose is 0.5 mg/kg intravenously or 1-2 mg/kg per rectum of the injectable solution.•
top
Dosage
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.
top
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.
top
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.
top
Availability
Diazepam is supplied in the following forms:
Tablets - 2mg, 5mg, 10mg
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
For inhalation administration:This method uses heating diazepam to form a vapor later producing an aerosol. This allows the drug to be passed through an inhalation route during an inhalation therapy.Provided in doses 2mg-20mg either in a single inhalation or multiple small inhalations [Pharmaceutical Patents. http://www.pharmcast.com/Patents100/Yr2004/Oct2004/101904/6805853_Diazepam101904.htm ]
top
Side effects
Diazepam has a range of side effects which are common to most benzodiazepines. Most common side effects include:
Suppression of REM sleep or dreaming
Rare paradoxical side effects can include: nervousness, irritability, insomnia, muscle cramps, and in extreme cases, rage, and violence.
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, but not to the anxiolytic and myorelaxant effects.
Patients with severe attacks of apnea during sleep may suffer respiratory depression (hypoventilation) leading to respiratory arrest and death.
Organic changes such as leukopenia
top
Interactions
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, probenecid, 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.
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 alter digoxin serum concentrations.
Smoking tobacco can enhance the elimination of diazepam and decrease its action.
Foods that acidify the urine can lead to faster absorption and elimination of diazepam, reducing drug levels and activity.
Foods that alkalinize the urine can lead to slower absorption and elimination of 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.
top
Contraindications
Use of diazepam should be avoided, when possible, in individuals with the following conditions:
Severe depression, particularly when accompanied by suicidal tendencies
Acute intoxication with alcohol, narcotics, or other psychoactive substances
top
Special caution needed
Less than 18 years of age - Treatment usually not indicated, except treatment of epilepsy, and pre-/postoperative treatment. The smallest possible effective dose should be used for this group of patients.
Under 6 months of age - Safety and effectiveness have not been established; diazepam should not be given to individuals in this age group.
Elderly and very ill patients - Possibility that apnea and/or cardiac arrest may occur. Concomitant use of other central nervous system depressants increases this risk. The smallest possible effective dose should be used for this group of patients..
I.V. or I.M. injections in hypotensive individuals or those in shock should be administered carefully and vital signs should be monitored.
top
Patients at a high risk for abuse and dependence
Diazepam can lead to physiological tolerance, and psychological and/or physical dependence. At a particularly high risk for diazepam misuse, abuse, and dependence are:
Patients with a history of alcohol or drug abuse or dependence
Emotionally unstable patients
Patients with chronic pain or other physical disorders
Patients from the aforementioned groups should be monitored very closely during therapy for signs of abuse and development of dependence. Discontinue therapy if any of these signs are noted. Long-term therapy in these patients is not recommended.
top
Withdrawal
Administration of therapeutic doses of diazepam for 6 weeks or longer can result in physical dependence, characterized by a withdrawal syndrome when the drug is discontinued. With larger doses, physical dependence develops more rapidly.
After continued therapy in excess of a few weeks, diazepam should never be stopped abruptly. The dose should instead be lowered gradually, over a period of 2 to 4 weeks, in order to minimize withdrawal symptoms.
Withdrawal symptoms are initially minimal, and increase in severity over the first 5 to 9 days after ingestion of the drug is stopped. Diazepam's long half-life and active metabolites delay the onset of such symptoms.
The withdrawal symptoms for diazepam are similar to those of other CNS depressants (e.g. alcohol, barbiturates), and can include
Abdominal and muscle cramps
Anorexia (i.e. lack of appetite)
In severe cases of diazepam withdrawal, symptoms can include:
Convulsions (i.e. seizures)
The more severe side effects usually only develop for patients who were treated with excessive doses for extended periods of time. Usually only the milder symptoms develop in patients terminating therapeutic-level treatment after several months.
top
Overdose
An individual who has consumed too much diazepam will display one or more of the following symptoms
Although not usually fatal when taken alone, a diazepam overdose is considered a medical emergency and generally requires the immediate attention of medical personnel. The antidote for an overdose of diazepam (or any other benzodiazepine) is flumazenil (Anexate®). This drug is only used in cases with severe respiratory depression or cardiovascular complications. Because flumazenil is a short-acting drug and the effects of diazepam can last for days, several doses of flumazenil may be necessary. Artificial respiration and stabilization of cardiovascular functions may also be necessary. Although not routinely indicated, activated charcoal can be used for decontamination of the stomach following a diazepam overdose. Emesis is contraindicated. Dialysis is minimally effective. Hypotension may be treated with levarterenol or metaraminol.
The oral LD50 (lethal dose in 50% of the population) of diazepam is 720mg/kg in mice and 1240mg/kg in rats.[ D. J. Greenblatt and colleagues reported in 1978 on two patients who had taken 2000 and 500 mg of diazepam, respectively, went into moderately deep comas, and were discharged within 48 hours without having experienced important complications in spite of having high concentrations of diazepam and its metabolites—desmethyldiazepam, oxazepam, and temazepam—according to samples taken in the hospital and as follow-up.]
Overdoses of diazepam with alcohol and/or other depressants may be fatal.
top
Recreational use
Generally, diazepam is not used as a recreational drug as frequently as alprazolam or flunitrazepam.
Diazepam is often found as an adulterant in heroin.• This may be because diazepam greatly amplifies the effects of opioids.
Sometimes diazepam is used by stimulant abusers to 'come down' and sleep and to help control the urge to binge• and also by users of LSD and other hallucinogens to help ease their trip without unpleasant after-effects.
top
Legal status
Internationally, diazepam is a Schedule IV drug under the Convention on Psychotropic Substances.•
top
Physical properties
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.•
top
Footnotes
|
|
