Benzodiazepines, Asians

Some herbal preparations, particularly some unbranded Asian imports, have been found to contain inactive fillers or adulterants. In one assessmenf, 24% of imporfed herbs were found fo confain ingredienfs nof on fhe label. These included specific medicafions (aspirin, caffeine, diurefics, and even benzodiazepines), nof fo menfion heavy mefals, such as lead. Some Asian for-mulafions may also confain animal componenfs. Therefore, if is advisable fo buy only producfs fhaf lisf fhe following informafion bofanical name or names,... 

Clobazam, a 1,5-benzodiazepine, differs in its chemical structure from most other benzodiazepines. It has been claimed to have less sedative effects for its effective anticonvulsant and anti-anxiety effects (SED-12, 98). Whether because of tolerance or not, clobazam tends to be less sedative than clonazepam. Both the therapeutic and adverse effects of clobazam have been related to its major metabolite Al-desmethylclobazam, the formation of which depends on CYP2C19 activity. Mutant alleles that confer high CYP2C19 activity, and are therefore associated with high concentrations of the metabolite, are particularly common (30-40%) in Asian populations (1)-... 

A genetic factor in Asians causes an undesirable side effect when administered the standard dose of benzodiazepines (diazepam [Valium]) alprazolam [Xanax], tricyclic antidepressants, atropine, and propranolol [Inderal],... 

CYP2C19 Benzodiazepines diazepam Antidepressants imipramine, amitriptyline, clomipramine, citalopram Others propranolol, hexobarbital, mephobarbital, proguanil, omeprazole, S-mephenytoin 2 no activity 23%-39% in Asians 13% in Caucasians 25% in African Americans 3 no activity 6%-10% in Asians 0% in others... 

In the fourth chapter, Drs. Edmond H. Pi and Gregory E. Gray review the pharmacokinetics, pharmacodynamics, and sociocultural influences on the psychotropic responses among Asian American populations. Particular consideration is given to anti-psychotics, antidepressants, benzodiazepines, and lithium. The authors stress the importance of prescribing the lowest possible effective dose, to minimize untoward side effects and thus ensure treatment compliance. 

Salzman described a downregulation of benzodiazepine and P-blocker receptors linked to ageing. It has been postulated that Asians have fewer benzodiazepine and P-blocker receptors than Caucasians. Downregulation of these receptors with age (Salzman, 1982) has been described and postulated by Zhou et al. (1990), but hard evidence of racial or ethnic differences is still awaited. If the Chinese are more sensitive to propranolol in spite of their high catabolic rate, it might be linked to adrenergic receptor sensitivity. 

---