Phenylketonuria (PKU) is an autossomal recessive disease caused by phenylalanine-4-hydroxylase deficiency, which is a liver-specific enzyme that catalyzes the hydroxylation of l-phenylalanine (Phe) to l-tyrosine (Tyr). The deficiency of this enzyme leads to the accumulation of Phe in the tissues and plasma of patients. The clinical characterization of this disease is mental retardation and other neurological features. The mechanisms of brain damage are poorly understood. Oxidative stress is observed in some inborn errors of intermediary metabolism owing to the accumulation of toxic metabolites leading to excessive free radical production and may be a result of restricted diets on the antioxidant status. In the present study we evaluated various oxidative stress parameters, namely thiobarbituric acid-reactive species (TBA-RS) and total antioxidant reactivity (TAR) in the plasma of PKU patients. The activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were also measured in erythrocytes from these patients. It was observed that phenylketonuric patients present a significant increase of plasma TBA-RS measurement, indicating a stimulation of lipoperoxidation, as well as a decrease of plasma TAR, reflecting a deficient capacity to rapidly handle an increase of reactive species. The results also showed a decrease of erythrocyte GSH-Px activity. Therefore, it is presumed that oxidative stress is involved in the pathophysiology of the tissue damage found in PKU.
Objective
To evaluate the labeling preferences of medication users and characterize their perceptions of the comprehensibility and readability of medication labels.
Methods
We conducted a population-based cross-sectional study of medication users aged 18 years or older in 10 Brazilian capital cities. Perceptions of the comprehensibility and readability of medication labels in relation to sociodemographic characteristics were evaluated by Poisson regression models with robust variance. Labeling preferences were assessed through questions addressing possible improvements and through the use of digitally simulated packages.
Results
Of 6,255 medication users interviewed, more than half found it difficult or very difficult to read (50.8%) and/or understand (52.0%) medication labels. Difficulties were more pronounced for participants aged 40 years or older, with lower levels of education, and non-whites. Increasing the font size (93.7%), describing the indications for use (95.9%) and contraindications (95.6%) on the label, and highlighting the expiration date (96.3%) were the most widely accepted improvements. In the evaluation of simulated packages, users preferred factors that improved readability, such as increased font size, use of graphic elements and color to highlight the concentration of the active ingredient, and contrast between the font color and background. The new simulated package design, with increased font size, color to highlight the concentration and contrast between the font color and background, was preferred over the standard design by 77.0% of participants.
Conclusion
Based on users’ perceptions, increased font size and use of graphic elements and color to emphasize critical information, such as expiration date and concentration, are factors that contribute to making medication labels clearer to users. Pharmaceutical industries and policy makers should consider these items when developing labels and defining policies on this issue.
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