Lorazepam and Diazepam - What's the difference?
Lorazepam vs Diazepam
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Lorazepam and Diazepam are benzodiazepine tranquilizers with short to medium duration of action. They both possess the five characteristic benzodiazepine effects: anxiolytic, sedative/hypnotic, amnesic, anticonvulsant and muscle relaxant.
Diazepam was approved for use in 1963, and Lorazepam was introducted in 1971.
The two medications have much in common, being used to relieve anxiety, nervousness, and tension associated with anxiety disorders. They are also used to treat certain types of seizure disorders and to relieve insomnia (induce sleep).
Due to their anticonvulsant, or CNS depressant, properties the medications are useful for the prevention and treatment of alcohol or (especially Diazepam) opiate withdrawal symptoms. The fact that these drugs do not require oxidation, hepatic or otherwise, for their metabolism makes them particularly suitable for the case.
Both Diazepam and Lorazepam can be used as a premedication for inducing sedation, anxiolysis or amnesia prior to certain medical procedures (like dentistry or endoscopy) to reduce anxiety. In addition, Lorazepam may be used as an adjunct antiemetic in chemotherapy.
Lorazepam is a more potent drug than Diazepam. 1mg of Lorazepam is equal in effect to 10mg of Diazepam. Moreover, Lorazepam has a higher addictive potential, compared to other benzodiazepines, including Diazepam.
Peak blood levels after the intravenuous injection are reached within 15 minutes for Diazepam and within 10 minutes for Lorazepam. When taken orally, the medications reach peak blood levels in 60 minutes and in 120 minutes correspondingly.
Both medications are nearly insoluble in water, but unlike Lorazepam, Diazepam has a good lipid solubility. Lorazepam is absorbed relatively slowly by mouth and is unsuitable for rectal administration. It is mainly distributed vascularly. On the contrary, Diazepam, which is well absorbed orally and rectally, with its high lipid solubility, does not remain in the vascular space but quickly redistributes from the serum all over the body, particularly to body fat. That is why one Lorazepam dose has longer duration of effect than one Diazepam dose. Lorazepam stays in the vascular space for a longer period of time, making the anticonvulsant effects more durable, and reducing the need for repeated doses. Diazepam anticonvulsant/sedative effects wear off after 15-30 minutes, but Lorazepam effects last 12-24 hours. So, in the treatment of seizures in epileptic patients, Lorazepam is usually considered to be more preferable than Diazepam when used intravenuously.
On the other hand, the advantage of Diazepam is less severe withdrawal symptoms when the medication is discontinued. Both medications should be stopped by gradually decreasing the dose. But in the case of Diazepam these dose reductions are felt less acutely, because of the longer half lives (20-200 hours) of Diazepam and its active metabolites.
Diazepam is typically administeres in dosages from 2mg to 30mg per dose. The initial dose of Lorazepam is usually 0.5mg, and dosages above 2mg at a time should be avoided.
Lorazepam's most popular brand name is Ativan. Diazepam is well-known under the brand name Valium.
See also Lorazepam, Diazepam.