|Bioavailability||44% (oral route), 53% (sublingual), 98% (intranasal) []|
|Biological half-life||1.5–5.5 hours|
|Chemical and physical data|
|Molar mass||343.2 g/mol|
|3D model (Jmol)|
Triazolam (original brand name Halcion) is a central nervous system (CNS) depressant in the benzodiazepine class. It possesses pharmacological properties similar to that of other benzodiazepines, but it is generally only used as a sedative to treat severe insomnia. In addition to the hypnotic properties triazolam possesses, amnesic, anxiolytic, sedative, anticonvulsant and muscle relaxant properties are also present. Due to its short half-life, triazolam is not effective for patients that suffer from frequent awakenings or early wakening.
Triazolam was initially patented in 1970 and went on sale in the United States in 1982.
Triazolam is usually used for short-term treatment of acute insomnia and circadian rhythm sleep disorders, including jet lag. It is an ideal benzodiazepine for this use because its fast onset of action and short half-life. It puts one to sleep for not more than 1.5 hours (approximately 1–2 hours), allowing its user to avoid morning drowsiness. Triazolam is also sometimes used as an adjuvant in medical procedures requiring anesthesia or to reduce anxiety during brief events like MRI scans and non-surgical dental procedures. Triazolam is ineffective in maintaining sleep however, due to its short half-life with quazepam showing superiority.
Triazolam is frequently prescribed as a sleep aid for passengers travelling on short to medium duration flights. If this use is contemplated, it is especially important to avoid the consumption of alcoholic beverages, and to do a ground based "trial" of the medication to ensure that the side effects and potency of this medication are understood by the user prior to using it in a relatively more public environment (as disinhibition can be a common side effect, with potentially severe consequences).
Adverse drug reactions associated with the use of triazolam include:
- Relatively common (>1% of patients): somnolence, dizziness, feeling of lightness, coordination problems.
- Less common (0.9% to 0.5% of patients): euphoria, tachycardia, tiredness, confusional states/memory impairment, cramps/pain, depression, visual disturbances.
- Rare (<0.5% of patients): constipation, taste alteration, diarrhea, dry mouth, dermatitis/allergy, dreams/nightmares, insomnia, parasthesia, tinnitus, dysesthesia, weakness, congestion.
Triazolam, although a short-acting benzodiazepine, may still cause residual impairment into the next day, especially the next morning. A meta-analysis demonstrated that residual "hangover" effects after nighttime administration of triazolam such as sleepiness, impaired psychomotor, and cognitive functions may persist into the next day, which may impair the ability of users to drive safely and increase risks of falls and hip fractures. Confusion and amnesia has been reported.
Tolerance, dependence, and withdrawal
A review of the literature found that long-term use of benzodiazepines, including triazolam, is associated with drug tolerance, drug dependence, rebound insomnia, and CNS related adverse effects. It recommended that benzodiazepine hypnotics are used at their lowest possible dose and for a short period of time. Non-pharmacological treatment options however, were found to have sustained improvements in sleep quality. A worsening of insomnia (rebound insomnia) compared to baseline may occur after discontinuation of triazolam even after short-term single-nightly-dose therapy.
Other withdrawal symptoms can range from mild unpleasant feelings to a major withdrawal syndrome, including stomach cramps, vomiting, muscle cramps, sweating, tremor, and, in rare cases, convulsions.
Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, alcoholics, or other drug-dependent individuals and individuals with comorbid psychiatric disorders. Triazolam belongs to the Pregnancy Category X of the FDA. This means that it is known to have the potential to cause birth defects.
Triazolam, similar to other benzodiazepines and nonbenzodiazepines, causes impairments in body balance and standing steadiness in individuals who wake up at night or the next morning. Falls and hip fractures are frequently reported. The combination with alcohol increases these impairments. Partial, but incomplete tolerance develops to these impairments. There can be daytime withdrawal effects.
An extensive review of the medical literature regarding the management of insomnia and the elderly found that there is considerable evidence of the effectiveness and durability of non-drug treatments for insomnia in adults of all ages and that these interventions are underutilized. Compared with the benzodiazepines including triazolam, the nonbenzodiazepine sedative-hypnotics appeared to offer few, if any, significant clinical advantages in efficacy or tolerability in elderly persons. It was found that newer agents with novel mechanisms of action and improved safety profiles, such as the melatonin agonists, hold promise for the management of chronic insomnia in elderly people. Long-term use of sedative-hypnotics for insomnia lacks an evidence base and has traditionally been discouraged for reasons that include concerns about such potential adverse drug effects as cognitive impairment, anterograde amnesia, daytime sedation, motor incoordination, and increased risk of motor vehicle accidents and falls. One study found no evidence of sustained hypnotic efficacy throughout the 9 weeks of treatment for triazolam.
In addition, the effectiveness and safety of long-term use of these agents remain to be determined. It was concluded that more research is needed to evaluate the long-term effects of treatment and the most appropriate management strategy for elderly persons with chronic insomnia.
Ketoconazole and Itraconazole have a profound effect on the pharmacokinetics of triazolam, leading to greatly enhanced effects. Anxiety, tremor and depression have been documented in a case report following administration of nitrazepam and triazolam. Following administration of erythromycin, repetitive hallucinations and abnormal bodily sensations developed. The patient had, however, acute pneumonia and renal failure. Co-administration of benzodiazepine drugs at therapeutic doses with erythromycin may cause serious psychotic symptoms, especially in those with other physical complications. Caffeine reduces the effectiveness of triazolam. Other important interactions include cimetidine, diltiazem, erythromycin, fluconazole, grapefruit juice, isoniazid, itraconazole, ketoconazole, nefazodone, rifampicin, ritonavir, and troleandomycin. Triazolam should not be administered to patients on Atripla.
Symptoms of an overdose include
- Hypoventilation (respiratory depression)
- Somnolence (drowsiness)
- Slurred speech
- Seizures have been reported.
The pharmacological effects of triazolam are similar to those of most other benzodiazepines. Triazolam does not generate active metabolites. Triazolam is a short acting benzodiazepine, is lipophilic, and is metabolised hepatically via oxidative pathways. The main pharmacological effects of triazolam are the enhancement of the neurotransmitter GABA at the GABAA receptor. The half-life of triazolam is only 2 hours making it a very short acting benzodiazepine drug. Triazolam has anticonvulsant effects on brain function.
Society and culture
Marketed in English-speaking countries under the brand names Apo-Triazo, Halcion, Hypam, and Trilam. Other (designer) names include 2'-chloroxanax, chloroxanax, 2'-chloro-alprazolam, triclazolam, and chlorotriazolam.
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