Cimetidine (Tagamet in the USA) which is sold OTC as an acid blocker/heartburn medication can have a very interesting effect on benzos
It will not make benzos any stronger (from SWIM
's experience anyway), but what it will do is greatly impact the time it takes for the benzos to be cleared from the body. There are a couple of benzos (oxazepam "Serax," and lorazepam
") which are both immune to the effects of cimetidine, but the rest of the benzos are not immune.
"The effect of cimetidine on the metabolism of benzodiazepines
is discussed. Studies of cimetidine's inhibition of benzodiazepine
metabolism by liver microsomal enzyme pathways are described. Cimetidine is known to have this effect on the metabolism of diazepam
, and because chlorazepate and prazepam
are similarly metabolized, cimetidine is likely to have the same effect on the metabolism of these drugs
. Oxazepam and lorazepam are two benzodiazepines not metabolized by liver microsomal enzymes, but are thought to be glucuronidated in peripheral tissue by glucuronyl transferase. Cimetidine has been shown not to alter the pharmacokinetics of lorazepam or oxazepam when administered concurrently with either of these benzodiazepines. When it is necessary to treat a patients receiving cimetidine with a benzodiazepine, oxazepam or lorazepam may be the drug
of choice. "
"Cimetidine/Benzodiazepines: This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment. Medical warning: Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs: When these two medicines are taken together, your body may not process benzodiazepines properly. What might happen: The effects of benzodiazepines may increase and cause excessive drowsiness. What you should do about this interaction: If you experience excessive drowsiness, contact your doctor. It may be necessary to change one or both of your medicines.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
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16.Greenblatt DJ, Locniskar A, Scavone JM, Blyden GT, Ochs HR, Harmatz JS, Shader RI. Absence of interaction of cimetidine and ranitidine with intravenous and oral midazolam
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17.Locniskar A, Greenblatt DJ, Harmatz JS, Zinny MA, Shader RI. Interaction of diazepam with famotidine and cimetidine, two H2-receptor antagonists. J Clin Pharmacol 1986 Apr;26(4):299-303.
18.Friedman H, Greenblatt DJ, Burstein ES, Scavone JM, Harmatz JS, Shader RI. Triazolam kinetics: interaction with cimetidine, propranolol, and the combination. J Clin Pharmacol 1988 Mar;28(3):228-33.
19.Andersson T, Andren K, Cederberg C, Edvardsson G, Heggelund A, Lundborg P. Effect of omeprazole and cimetidine on plasma diazepam levels. Eur J Clin Pharmacol 1990;39(1):51-4.
20.Sanders LD, Whitehead C, Gildersleve CD, Rosen M, Robinson JO. Interaction of H2-receptor antagonists and benzodiazepine sedation. A double-blind placebo-controlled investigation of the effects of cimetidine and ranitidine on recovery after intravenous midazolam. Anaesthesia 1993 Apr;48(4):286-92."
PS SWIM is aware that his post doesn't actually detail any "legals that make benzos stronger," however, SWIM feels strongly that the "legal" he's pointing out here certainlly deserves an honorable mention.