Ratio of abdominal sagittal diameter to height is strong indicator of coronary risk: Table 1

Prescribing antidepressants in general practiceWhat is an effective dose?Editor-What should be the advised dosage of a tricyclic antidepressant for major depression?In his editorial Tony Kendrick quotes a recommended dose of a typical tricyclic antidepressant, amitriptyline, as 125 mg daily. 1 This dosage is at the higher end of the range of dosages quoted for all tricyclic antidepressants in the British National Formulary.If followed it would have major implications for the prescribing habits of general practitioners.The recommended dosage for amitriptyline for major depression is quoted from a consensus statement published in the BMJ in 1992. 2 The source of this recommendation is a double blind placebo controlled trial of amitriptyline among depressed patients in general practice. 3 In this trial patients given the active drug received amitriptyline 75 mg daily by the end of the first week, amitriptyline 100 mg during the second week, and amitriptyline 125-175 mg, depending on improvement, during the remaining four weeks of the study.The median dose of amitriptyline given over the six week study period was 125 mg.It is the median tolerated dose.Figure 1 in the paper by Hollyman et al clearly shows a response to treatment in the first two weeks, when the lower dose of amitriptyline was given. 3 Kendrick discusses the results of several investigations into the effectiveness of antidepressants at different dosages.Similar investigations have been used to develop the dose range of every prescribable antidepressantfor example, Kerihuel and Dreyfus reviewed 34 randomised clinical trials of lofepramine. 4 In the papers reviewed the concentration of lofepramine giving a clinical response ranged from 105 mg to 210 mg, which is equivalent to 75-150 mg amitriptyline.The principle that more severe cases of major depression require higher doses of antidepressants is also valid.It also holds true for newer selective serotonin reuptake inhibitors.For example, a study of prescribing patterns across 23 381 prescriptions shows that a prescription for higher than the initial dose was required in 6.8% of patients taking fluoxetine, 21.1% of patients taking paroxetine, and 51% of patients taking sertraline. 5