Oxazepam

Oxazepam is a short-to-intermediate-acting benzodiazepine.[3][4] Oxazepam is used for the treatment of anxiety [5][6] and insomnia and in the control of symptoms of alcohol withdrawal syndrome.

Oxazepam
Clinical data
Trade namesSerax, Alepam, Generics
Routes of
administration		Oral
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)
  • CA: Schedule IV
  • DE: Prescription only (Anlage III for higher doses)
  • US: Schedule IV
Pharmacokinetic data
Bioavailability95.5%
MetabolismHepatic
Elimination half-life5–15 h[1]
ExcretionRenal
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.009.161
Chemical and physical data
FormulaC15H11ClN2O2
Molar mass286.71 g·mol−1
3D model (JSmol)
Melting point205 to 206 °C (401 to 403 °F)
  (verify)

It is a metabolite of diazepam, prazepam, and temazepam,[7] and has moderate amnesic, anxiolytic, anticonvulsant, hypnotic, sedative, and skeletal muscle relaxant properties compared to other benzodiazepines.[8]

It was patented in 1962 and approved for medical use in 1964.[9]

Medical uses

It is an intermediate-acting benzodiazepine with a slow onset of action,[10] so it is usually prescribed to individuals who have trouble staying asleep, rather than falling asleep. It is commonly prescribed for anxiety disorders with associated tension, irritability, and agitation. It is also prescribed for drug and alcohol withdrawal, and for anxiety associated with depression. Physicians may use oxazepam outside its approved indications to treat social phobia, post-traumatic stress disorder, insomnia, premenstrual syndrome, and other conditions.[11]

Side effects

The side effects of oxazepam are similar to those of other benzodiazepines, and may include dizziness, drowsiness, headache, memory impairment, paradoxical excitement, and anterograde amnesia, but does not affect transient global amnesia. Side effects due to rapid decrease in dose or abrupt withdrawal from oxazepam may include abdominal and muscle cramps, convulsions, depression, inability to fall asleep or stay asleep, sweating, tremors, or vomiting.[12]

Tolerance, dependence and withdrawal

Oxazepam, as with other benzodiazepine drugs, can cause tolerance, physical dependence, addiction, and benzodiazepine withdrawal syndrome. Withdrawal from oxazepam or other benzodiazepines often leads to withdrawal symptoms which are similar to those seen during alcohol and barbiturate withdrawal. The higher the dose and the longer the drug is taken, the greater the risk of experiencing unpleasant withdrawal symptoms. Withdrawal symptoms can occur, though, at standard dosages and also after short-term use. Benzodiazepine treatment should be discontinued as soon as possible by a slow and gradual dose reduction regimen.[13]

Contraindications

Oxazepam is contraindicated in myasthenia gravis, chronic obstructive pulmonary disease, and limited pulmonary reserve, as well as severe hepatic disease.

Special precautions

Benzodiazepines require special precautions if used in the elderly, during pregnancy, in children, alcohol- or drug-dependent individuals, and individuals with comorbid psychiatric disorders.[14] Benzodiazepines including oxazepam are lipophilic drugs and rapidly penetrate membranes, so rapidly crosses over into the placenta with significant uptake of the drug. Use of benzodiazepines in late pregnancy, especially high doses, may result in floppy infant syndrome.[15]

Pregnancy

Oxazepam when taken during late in pregnancy, the third trimester, causes a definite risk to the neonate including a severe benzodiazepine withdrawal syndrome including hypotonia, and reluctance to suck, to apnoeic spells, cyanosis, and impaired metabolic responses to cold stress. Floppy infant syndrome and sedation in the newborn may also occur. Symptoms of floppy infant syndrome and the neonatal benzodiazepine withdrawal syndrome have been reported to persist from hours to months after birth.[16]

Interactions

As oxazepam is an active metabolite of diazepam, an overlap in possible interactions is likely with other drugs or food, with exception of the pharmacokinetic CYP450 interactions (e.g. with cimetidine). Precautions and following the prescription are required when taking oxazepam (or other benzodiazepines) in combinations with antidepressant medication (SSRIs such as fluoxetine, sertraline, and paroxetine, or multiple reuptake inhibitors such as bupropion, duloxetine, or venlafaxine), potent painkillers (opioids, e.g. morphine, oxycodone or methadone). Concurrent use of these medicines (as well as other benzodiazepines) can interact in a way that is difficult to predict. Drinking alcohol when taking oxazepam is not recommended. Concomitant use of oxazepam and alcohol can lead to increased sedation, severe problems with coordination (ataxia), decreased muscle tone, and in severe cases or in predisposed patients, even to life-threatening intoxications with respiratory depression, coma, and collapse. There is a risk of blood circulation collapse, possibly the same condition as blood circulation syncope, when oxazepam is used in combination with quetiapine, an antipsychotic.

Overdose
Main article: Benzodiazepine overdose

Oxazepam is generally less toxic in overdose than other benzodiazepines.[17] Important factors which affect the severity of a benzodiazepine overdose include the dose ingested, the age of the patient, and health status prior to overdose. Benzodiazepine overdoses can be much more dangerous if a coingestion of other CNS depressants such as opiates or alcohol has occurred. Symptoms of an oxazepam overdose include:[18][19][20]

Pharmacology

Oxazepam is an intermediate-acting benzodiazepine of the 3-hydroxy family; it acts on benzodiazepine receptors, resulting in increased effect of GABA to the GABAA receptor which results in inhibitory effects on the central nervous system.[21][22] The half-life of oxazepam is four to 15 hours.[23] It has been shown to suppress cortisol levels.[24] Oxazepam is the most slowly absorbed and has the slowest onset of action of all the common benzodiazepines according to one British study.[25]

Oxazepam is an active metabolite formed during the breakdown of diazepam, nordazepam, and certain similar drugs. It may be safer than many other benzodiazepines in patients with impaired liver function because it does not require hepatic oxidation, but rather, it is simply metabolized by glucuronidation, so oxazepam is less likely to accumulate and cause adverse reactions in the elderly or people with liver disease. Oxazepam is similar to lorazepam in this respect. (1) Preferential storage of oxazepam occurs in some organs, including the heart of the neonate. Absorption by any administered route and the risk of accumulation is significantly increased in the neonate, and withdrawal of oxazepam during pregnancy and breast feeding is recommended, as oxazepam is excreted in breast milk.[26]

2 mg of oxazepam equates to 1 mg of diazepam according to the benzodiazepine equivalency converter, therefore 20 mg of oxazepam according to BZD equivalency equates to 10 mg of diazepam and 15 mg oxazepam to 7.5 mg diazepam (rounded up to 8 mg of diazepam).[27] 10 mg of oxazepam equates to 5 mg of diazepam according to that converter. So the equivalent amount of oxazepam in milligrams is one half of the equivalent amount of diazepam in milligrams. The ratio is 2:1 (2 to 1 in milligrams), when 2 is the amount of oxazepam in milligrams, and 1 is the amount of diazepam in milligrams. Converted, when 1 is the amount of diazepam in milligrams and 2 is the amount of oxazepam in milligrams, the ratio is 1:2 (1 to 2).

Some BZD equivalency converters use 3 to 1 (oxazepam to diazepam), 1 to 3 (diazepam to oxazepam) as the ratio (3:1 and 1:3), so 15 mg of oxazepam would equate to 5 mg of diazepam.[28] It is best to take into account all of the qualities of the benzodiazepines in question, and remember that these are just approximations and guidelines. Not all of the doctors - physicians and psychiatrists - agree on the same benzodiazepine equivalency converter ratio. Only a health care professional can make a judgment on an individual patient's medication. The conversion of medication is counted in milligrams, that is weight. Different tablets (pills) have a different amount of medicine in them in milligrams. Pills can often be halved (halfed), either with fingers along the halving (halfing) line, or with a pill cutter.

Chemistry

Oxazepam exists as a racemic mixture.[29] Early attempts to isolate enantiomers were unsuccessful; the corresponding acetate has been isolated as a single enantiomer. Given the different rates of epimerization that occur at different pH levels, it was determined that there would be no therapeutic benefit to the administration of a single enantiomer over the racemic mixture.[30]

Frequency of use

Oxazepam, along with diazepam, nitrazepam, and temazepam, were the four benzodiazepines listed on the pharmaceutical benefits scheme and represented 82% of the benzodiazepine prescriptions in Australia in 1990-1991.[31]

Society and culture

Misuse
See also: Benzodiazepine drug misuse

Oxazepam has the potential for misuse, defined as taking the drug to achieve a high, or continuing to take the drug in the long term against medical advice.[32] Benzodiazepines, including diazepam, oxazepam, nitrazepam, and flunitrazepam, accounted for the largest volume of forged drug prescriptions in Sweden from 1982 to 1986. During this time, a total of 52% of drug forgeries were for benzodiazepines, suggesting they were a major prescription drug class of abuse.[33]

However, due to its slow rate of absorption and its slow onset of action,[25] oxazepam has a relatively low potential for abuse compared to some other benzodiazepines, such as temazepam, flunitrazepam, or triazolam, which have a high potential for abuse similar to barbiturates.[34]

Oxazepam is a Schedule IV drug under the Convention on Psychotropic Substances.[35]

Brand names

It is marketed under many brand names worldwide, including: Alepam, Alepan, Anoxa, Anxiolit, Comedormir, durazepam, Murelax, Nozepam, Oksazepam, Opamox, Ox-Pam, Oxa-CT, Oxabenz, Oxamin, Oxapam, Oxapax, Oxascand, Oxaze, Oxazepam, Oxazépam, Oxazin, Oxepam, Praxiten, Purata, Selars, Serax, Serenal, Serepax, Seresta, Séresta, Serpax, Sobril, Tazepam, Vaben, and Youfei.[36]

It is also marketed in combination with scopolamine as Novalona and in combination with alanine as Pausafrent T.[36]

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