| According to the fact that the drug response in each individual is variable, therapeutic drug monitoring (TDM) is thus helpful in optimal dosage adjustment in each patient. This is acceptable in drug with narrow therapeutic level and clinical response correlating with drug level. Objective= This cross sectional study is aimed to evaluate the appropriateness of TDM process in psychiatric patients using mood stabilizers. Materials and Methods= The data is retrospectively collected from patients prescribing mood stabilizers and TDM are ordered during April-August 2013 in Prasrimahabhodi Psychiatric Hospital. The data is determined in terms of indication and sampling time in each TDM. Moreover, the correlation between steady state concentrations and clinical response is also identified. Results= There are 89 cases of TDM of mood stabilizers. Of those, there are TDM of lithium 14 cases (15.7%) and valproate 75 cases (84.3%). The results revealed that there was more than one indication in each TDM. The indications were appropriate in 86 cases (96.9%), while there were 3 inappropriate indications (3.3%). The common indications for TDM are from initiation of therapy or dosing adjustment, unresponsive to treatment, non-compliance and drug toxicity. In addition, the sampling times are found to be suitable in 81 cases (91.0%) and unsuitable in 8 cases (9.0%). The obtaining drug concentrations were in Subtherapeutic level in 21 cases (23.6%), Therapeutic range in 59 cases (66.3%) and Overtherapeutic in 9 cases (10.1%). In terms of the correlations between drug levels and clinical responses, the results indicated that drug levels are well correlated with the responses in 49 cases (55.1%) and non-correlated in 40 cases (44.9%). Moreover, the obtaining drug levels and the calculated drug concentrations are insignificantly different (lithium, p – value = 0.234; valproate, p – value = 0.395). Conclusion= Therapeutic drug monitoring with appropriate indications and sampling times was clinically useful and help promote optimal drug therapy in each patient. |