Prevalence, awareness, treatment and control of hypertension in the Palestinian population.

We determined the prevalence of hypertension and the level of awareness, treatment and control of hypertension among Palestinian adults in a population-based cross-sectional survey. Two-stage stratified sampling method was used to select 2077 participants from the general population aged 25 years and over. Trained observers obtained two blood pressure (BP) measurements from each individual by the use of a standardized mercury sphygmomanometer after a 5-min sitting rest. Information on sociogeographical factors and antihypertensive medications was obtained using a standard questionnaire. Hypertension was defined as a mean systolic BP (SBP) 140 mm Hg, diastolic BP (DBP) 90 mm Hg, and/or use of antihypertensive medications. The overall prevalence of hypertension was 27.6%, with a higher percentage among men (29.2 vs 26.4%; P=0.04). Hypertension increased with age in both men and women. Among hypertensive patients, 51.0% were aware of their elevated BP, 40.2% had treatment and only 9.5% achieved targeted BP control (<140/90 mm Hg). Patients under antihypertensive treatment showed SBP and DBP that were only 3.1 mm Hg and 2.5 mm Hg lower than individuals without antihypertensive treatment, respectively. The data show that hypertension prevalence among Palestinian adults is high, whereas the proportions of awareness treatment and control of hypertension were low. Concerted public health effort is urgently required to improve the detection, treatment and control of hypertension in Palestine.

High clearance of (S)-warfarin in a warfarin-resistant subject.

A 30 year old black male required a 60 mg daily dose of warfarin to elicit a therapeutic anticoagulant response (normal warfarin dose 2.5-10 mg day-1; maximum 15 mg day-1). Hereditary warfarin resistance was suspected after compliance, diet, concurrent medication and any gastrointestinal disorder were eliminated as contributory causes. The disposition of vitamin K and vitamin K epoxide was examined in the propositus, his two sisters and 13 control black male subjects. Each subject was given an i.v. bolus dose (5 mg) of vitamin K prior to and after 2 weeks of warfarin therapy (5 mg day-1). The oral clearances of (S)- and (R)-warfarin were also measured in each subject during the last day of warfarin therapy. The mean (+/- s.d.) systemic clearance of vitamin K was similar in all subjects before (114 +/- 35 ml min-1) and after (112 +/- 40 ml min-1) warfarin therapy. The mean (+/- s.d.) AUC value for vitamin K epoxide was increased by warfarin treatment (6.5 +/- 5.4 micrograms ml-1 min before and 139 +/- 78 micrograms ml-1 min after) in all subjects. In the propositus, the oral clearance of (S)-warfarin (14.5 ml min-1) and the clearance ratio for (S)/(R)warfarin (2.6) differed by more than 7 standard deviations from the control group (4.3 +/- 1.1 ml min-1 and 1.2 +/- 0.2, respectively). In one sister of the propositus, the stereoselective disposition of warfarin was comparable with that of her brother ((S)-warfarin clearance = 16.2 ml min-1; and (S)/(R)-warfarin clearance ratio = 2.7).

Reversible metabolism of vitamin K-vitamin K epoxide: modeling considerations and limitations.

Due to the cyclical natural of the vitamin K-vitamin K epoxide system, a two-compartment reversible metabolism model was used to describe this interconversion. In attempting to apply this model to the vitamin K-vitamin K epoxide cycle using literature data from dogs, interconversion and elimination clearances were obtained which are not physiologic. Consequently, the assumptions of the model were reexamined with respect to their validity. One critical assumption of the two-compartment model for interconversion is that it can only be applied in the absence of flow limitations. To determine what effect flow limitations may exert on the vitamin K and vitamin K epoxide apparent blood clearances, a model separating the liver from the blood compartment was proposed assuming the interconversion and metabolism of vitamin K and its epoxide occurred only within the liver. Simulated data suggested that if the reversible metabolic clearance values exceeded the distribution clearance terms, all the apparent clearances calculated using blood concentration-time data were in error. It is suggested that a two-compartment interconversion model might be too simplistic for the vitamin K-vitamin K epoxide cycle where the reversible metabolism is efficient and the distributional clearance may be rate limiting.