A multi-year survey of organic disinfection by-products in drinking waters of Castilla y León, Spain. The need and difficulty to comply with the legal limit of 2009.

This article explains the general difficulties of the Spanish source waters and climatic conditions regarding a control of trihalomethanes (THMs), as reflected by the case of Castilla y León, and how the median values of 75 and 163 microg L(-1) of years 1999 and 2002 gave way to the more moderate of 31 and 47 microg L(-1) of years 2006 and 2007, respectively--both the latter being measured during the warmer season. Particular circumstances such as raw surface water--with frequently high total organic carbon (T.O.C) values--being the source for 80% of population served, the moderate-to-high water temperatures during the warm seasons and the high chlorine dosages frequently applied account for such as high levels. The median global value (n = 98) for raw water T.O.C. was 4.26 mg L(-1) (90th percentile of 9.81 mg L(-1)) and a median T.O.C. removal of 30% was observed during the treatment, but with an enormous variety (a 90th percentile in the order of 70%). Regression analysis associated the variables raw water temperature, prechlorination dosage and raw and finished water T.O.C. with the THMs measured in the finished waters and in the distribution systems. A certain linear correlation exists between THMs and haloacetic acids (HAAs) contents. However, a shift on their profile is noticeable with the temperature of the water, so that above 11.12 degrees C, THMs concentration tends to be higher than that of HAAs, and vice versa.

A New Method for Individualized Digoxin Dosing in Elderly Patients.

BACKGROUND: Digoxin is a frequently prescribed drug in the elderly population. Estimated glomerular filtration rate is widely used to adjust dosages. The HUGE value is a tool for differentiating the presence or absence of chronic kidney disease in elderly patients. We aimed to investigate the usefulness of the HUGE value to predict the initial dose of digoxin in patients aged older than 70 years. METHODS: We reviewed retrospectively the medical records of patients aged older than 70 years with serum digoxin concentrations (SDCs) monitored over a 6-month period (63 patients). A linear regression relating the patient's SDC, maintenance dose of digoxin and the HUGE value was estimated to generate a dosage equation. This equation was validated retrospectively (33 patients) and prospectively (35 patients) in comparison with two existing methods based on creatinine clearance. RESULTS: An equation (HUGE_DIG) was generated to calculate the initial digoxin dose to reach a specific target SDC. Thus, to achieve a SDC of 0.8 ng/mL: Digoxin (mg/day) = 0.091 - 0.006 x HUGE. After retrospective validation, the calculated digoxin doses with this equation were administered in the prospective phase and we did not observe statistical differences between measured and desired SDCs. Moreover, the predictive performance of our equation was better than that obtained with the compared methods. CONCLUSIONS: We offer a new validated digoxin dosing equation for elderly patients. Our results support the need to perform digoxin dosing in elderly people, bearing in mind the changes in renal physiology secondary to ageing and not merely the estimated glomerular filtration rate.