Abstract: AIM: To study the influence of placenta acetyltransferase (NAT2) on acetylate phenotypes in pregnant and PIH women. METHODS: The samples of 20 ml urine were collected 2 h after a cup of 140mg-caffeine spiked coffee and the acetylator status were phenotyped by measuring the peak area of two caffeine metabolites, AFMU (5-acetylamino-6-formylamino-3-methyluracil) and 1X (1-methylxanthine) with high performance liquid chromatography (HPLC).Frequence distribution histograms were drawn to assess and compare slow and fast acetylate phenotype status among pregnant, PIH, and health women. RESULTS: The subjects were classified as slow acetylators if PAR <1.05 or as fast if PAR > 1.05, according to the data obtained from health women. The fast acetylators of pregnant and PIH women were 84.8 % and 92.9 %, respectively, much higher than that in health women by 72 %.There were no significant differences between PIH with and without urine protein.The mean AFMU/1X was lower in PIH with unusual urine protein than those without (P <0.01). CONCLUSION: The acetylator status of pregnant women can be affected by placenta acetyltransferase, and its routine determination may be used to ration drug therapy.

Key words: pharmacodynamics, N-acetylate phenotype, pregnancy, pregnancy- induced- hypertension, caffeine, polymorphism