title: Measurement of trough-to-peak ratios of four anti-hypertensive drugs on the basis of 24 h ambulatory blood pressure monitoring: different methods may give different results.
abstract: With 24 h ambulatory blood pressure monitoring (ABPM), the trough-to-peak (T/P) ratios (corrected for placebo) of atenolol 100 mg, cilazapril 2.5 mg, enalapril 20 mg and nifedipine-GITS 30 mg administered once daily for 4 weeks were determined in four groups of hypertensive patients. T/P ratios were calculated by three different methods: directly from the curves that averaged all individual 24 h profiles (A); averaging all individual T/P ratios after ABPM data were averaged for each patient over either 1 h intervals (B) or 3 h intervals (C). Methods B and C produced different values of T/P which, for each drug, were significantly higher with method C. With method A, nifedipine appeared to have the higher T/P. With methods B and C (which in contrast to method A, permitted statistical comparisons), differences between nifedipine and the other drugs were not significant. Meanwhile, method B appears to adhere most closely to FDA guidelines by taking more into account the interindividual variability of BP profile. Thus, we suggest that precise guidelines for measuring T/P on the basis of ABPM are needed, whereas for the comparison between drugs, both the mean value of the T/P and its variance must be determined.
authors.affiliation: Unidade de Farmacologia Clinica, Instituto de Farmacologia e Terapeutica da Faculdade de Medicina do Porto, Portugal.
authors.forename: G
authors.initials: G
authors.lastname: Gama
authors.forename: A
authors.initials: A
authors.lastname: Santos
authors.forename: J
authors.initials: J
authors.lastname: Polónia
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D018660:Blood Pressure Monitoring, Ambulatory; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
chemical_list: D000959:Antihypertensive Agents