Sir: We read the article by Pi & Zhu (2007) with interest, as this topic is particularly important to psychiatrists practising in countries like Sri Lanka, where, because of the lack of local prescribing guidelines, the dosing of medication is generally determined by guidelines developed for patients in the West, such as those from the National Institute for Health and Clinical Excellence (NICE) and the British National Formulary.
There are reports that Asian people generally require lower doses of psychotropic medications than White people and also that they have a lower threshold for extrapyramidal side-effects (Lin & Finder, 1983). This may be because of genetic and biological variations in pharmacokinetics and pharmacodynamics. Therefore it seems prudent to observe the rule of thumb ‘start low and go slow’ when prescribing psychotropics, in order to achieve a clinical improvement while avoiding adverse effects.
Self-adjustment of doses of medications is commonly seen among our patients, and that can lead to suboptimal therapeutic responses and more side-effects. Hence it is important to explain treatment decisions and the adjustment of doses.
Another factor which has to be kept in mind is that these patients may also be on concomitant herbal medication. There have been reports that some herbal medications (particularly Asian herbal mixtures) are contaminated with heavy metals (Ernst & Thompson Coon, 2001). Herbal medications may also be adulterated with prescription drugs or contain misidentified herbal ingredients. The presence of these constituents may alter the pharmacokinetic and pharmacodynamics of psychotropics, leading to toxic effects as well as suboptimal clinical improvement. Patients should be asked about the use of herbal medications, and be educated and cautioned with regard to the possible interactions between herbs and psychotropics.
Therefore, it is important to consider the inter-racial pharmacokinetic and pharmacodynamic differences as well as environmental and cultural factors when determining the dosage of psychotropics for our patients.
A. Hapangama1 and K. A. L. A. Kuruppuarachchi2
1Lecturer in Psychiatry, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka
2Professor of Psychiatry, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka, email lalithkuruppu@lycos.com
References
- Ernst, E. & Thompson Coon, J. (2001) Heavy metals in traditional Chinese medicines: a systematic review. Clinical Pharmacology and Therapeutics, 70, 497–504. [DOI] [PubMed] [Google Scholar]
- Lin, K. M. & Finder, E. (1983) Neuroleptic dosage for Asians. American Journal of Psychiatry, 140, 490–491. [DOI] [PubMed] [Google Scholar]
- Pi, E. H. & Zhu, W. (2007) New research advances in ethno-psychopharmacology: an Asian perspective. International Psychiatry, 4, 57–58. [PMC free article] [PubMed] [Google Scholar]
