Abstract

GARCIA BORGES, Lisandra et al. Development of a stable formulation of liquid urease for determination of serum urea. Rev Cubana Farm [online]. 2014, vol.48, n.3, pp.396-404. ISSN 0034-7515.

Introduction: determination of serum urea has great importance for the clinical diagnosis of several renal illnesses. The most implemented methods involve the use of the urease enzyme because of its high specificity for this analyte hydrolysis; the Berthelot method uses urease in the first reaction step followed by colorimetric reaction of the released ammonium. The presentation of urease in liquid form is one of the elements that make this process simpler, of easy and fast application with reliable results. Objective: to develop a stable urease solution as part of the diagnostic set for serum urea. Methods: the adequate formulation was designed and optimized by taking into account the enzyme concentration, the buffer solutions, the preserves and the polyhydroxyled organic compounds to attain a final stable liquid product. The parameters called specificity, precision, linearity, accuracy (comparison of methods) and sensitivity of the method were all evaluated in addition to the shelf life at 2 a 8 °C for 18 months. Results: astable liquid reagent (over 12 months at 2 a 8 °C ) was reached; the analytical method proved to be specific and linear up to 30 mmol/L of urea (r²= 0,999), sensitive, precise, with variation coefficient lower than 3 % and accurate ((r³ 0,999), satisfactory for the intended use of the product and the analytical quality comparable to that of the already existing products. Conclusions: the development of the stable liquid urease formulation will allow introducing this essential component in the reagent set for urea offered by the national industry to the healthcare system according to the requirements for commercialization (Reg 8-2001).

Keywords : urease; urea; clinical diagnosis; clinical laboratory.

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