Posted by Cam W. on December 30, 2001, at 5:22:36
In reply to strength of benzodiazipines, posted by The Missing Patient on December 29, 2001, at 22:43:19
MP - Most docs and all pharmacists should have a textbook with a list of benzodiazepines and their relative potencies and elimination half-lifes (the time it takes for half of the drug to leave the body).
Approximate Pharmacokinetic Properties of Benzodiazepines Available in Canada
Generic Name (Brand Name)[equivalent oral dose (mg) ; half-life incl. active metabolites (hours)] - use
Chlordiazepoxide (Librax™) [10 ; 100+] - antianxiety, sedative*.
Clorazepate (Tranxene™) [7.5 ; 100+] - antianxiety, sedative, sleep.
Diazepam (Valium™) [5 ; 100+] - antianxiety*, anticonvulsant, sedative*, sleep*.
Flurazepam (Dalmane™) [15 ; 100+] - sleep.
Alprazolam (Xanax™) [0.5 ; 12-15] - antianxiety, antipanic, sedative.
Bromazepam (Lectopam™) [6 ; 8-19] -antianxiety, sedative.
Clobamaz (Frisium™) [10 ; 10-46] - anticonvulsant.
Clonazepam (Rivotril™, Klonopin™) [1 ; 20-80] - antianxiety*, anticonvulsant, sedative*, sleep*.
Lorazepam (Ativan™, Somnel™)[1 ; 10-20] - anticonvulsant, antipanic* (SL), sedative, sleep.
Nitrazepam (Mogadon™) [5 ; 16-55] - anticonvulsant, sedative, sleep.
Oxazepam (Serax™) [15 ; 5-15] - antianxiety, sedative, sleep.
Temazepam (Restoril™) [15 ; 10-20] - sleep.
Midazolam (Versed™) [N/A ; 1-4 ] - sedative, sleep. (IV or IM only with anesthetics)
Triazolam (Halcion™) [0.25; 1.5-5] - dental anxiety*, sleep.
Okay, before anyone tears me apart over any of the figures, they were taken from at least 2 sources. Also, the uses with asterisks (*) are only "my opinion" based on my clinical experience. All others are the official uses as stated and determined by Health Canada.
As for the "safest" benzodiazepine, I do not think that it can be looked at that way. I believe that all benzodiazepines act fairly much the same at equivalent doses. The major differences between them is their fat solubility (ie. how readily it dissolves and is stored in the body's fat tissues), resulting in the differences in elimination half-lifes. Highly fat soluble (most longer half-life ones) benzodiazepines may build up in the body (not always) and low fat soluble (shorter half-life ones) can cause withdrawl symptoms to occur quicker when stopped.
Also, it is not usually "dangerous" to take benzodiazepines for longer than 4 weeks. You may have an increased risk of becoming dependent upon them, and tolerance to the psychomotor effects of benzodiazepines is more likely to occur. Manufacturers do recommend that if benzodiazepines are used for longer than 4 weeks, the dose should be tapered downward over an appropriate period of time (depends upon daily dose and length of therapy), instead of stopping the drug abruptly. Abruptly stopping a benzodiazepine that one has been taking for a long time, and especially if it is being taken at a relatively high daily dose, can result in an uncomfortable withdrawl syndrome (characterized by anxiety, insomnia, headaches, dizziness, tremor, sweating, nausea, cramps, ringing in ears, palpitation, and postural hypotension). In rare cases the benzodiazepine withdrawl syndrome has progressed to muscle twitching, confusional psychosis, paranoid psychosis, convulsions, hallucinations, and delirium tremens. I have never seen a benzodiazepine withdrawl syndrome this severe, but I have heard that it has happened. It may be these instances that would make one think that benzodiazepines are dangerous. As a rule, if used properly, benzodiazepines are among the safer (ie. less toxic, less lethal) of all of the drugs in a pharmacy (in relative terms).
I hope that this explains some of your concerns. - Cam