Allergy treatment in kids: Safety more than efficacy Expert cites ways to avoid pitfalls, ensure proper choice of agent
More than anything else, safety should be a physician's prime consideration when giving prescriptions to a child. In the view of Dr. Hugo Van Bever, professor of pediatrics at the National University of Singapore, safety comes before efficacy. "In my opinion the most important aspect is safety," he said. Van Bever spoke at the annual convention of the Philippine Academy of Pediatric Pulmonologists and meeting of the Asia-Pacific Association of Pediatric Allergologists and Respiratory Immunologists. Van Bever pointed out that because of the dearth of drug studies involving children, physicians are often forced to apply results of trials in adults to manage diseases in children-which should be done with great caution, if at all. Echoing Dr. Abraham Jacobi, regarded as the father of American pediatrics, Van Bever said, "children have special pharmacological features and should not be considered as miniature adults." Van Bever listed important considerations in individualizing drug regimens for children: o Age. Prescribing drugs to a premature infant is different from treating a full-term or an older baby. o Underlying disease. A lot of diseases are known to alter the pharmacologic properties of certain drugs. o Organ function. Liver or kidney malfunction, for instance, compromises drug metabolism and excretion. Renal function affects the elimination of drugs. o Concomitant conditions. The presence of fever in acute infections and chronic inflammatory diseases hastens the excretion of drugs. To avoid pitfalls, physicians should rely more on carefully derived data from clinical studies involving children. Van Bever gave three "simple rules" to consider when reviewing drug studies involving children: o Check whether or not control subjects are involved and whether or not it is a placebo-controlled study. Van Bever pointed out that the placebo effect is real and also occurs in infants. Receiving placebo treatment offers no significant clinical effects, but being part of a placebo group does have effects. "It's not psychological. It has something to do with being in a trial, and in most studies, it is acceptable that you would have a placebo of 35 percent in the end," he explained. o Make sure that the patients selected for the study needed the drug. Patient selection is vital, according to Van Bever. For the results to be valuable, the subjects must not only have the disease for which the drug is being tested, but that disease must be of a certain level of severity, he explained. o Follow the rules of good pharmacology based on dose-response curve. "If anybody is able to prove that a lower dose is better than a higher dose, there's always something wrong ... that you have to figure out," said Van Bever.
Although there are studies that fail Van Bever's three rules of a good study design, there are well-designed studies available to guide pediatricians in treating children with atopic conditions. "We have safe and effective medications to control, not to cure, allergy and asthma," he said. In the case of inhaled steroids, numerous studies attest to their efficacy and safety in children. Continuous use for more than 20 years has shown no growth stunting even with high doses. Like those of inhaled steroids, the merits of short-acting beta-agonists are also firmly established. Anticholinergics are suitable alternatives; although as safe as beta-agonists, they are not as effective. The efficacy of leukotriene-receptor antagonists against asthma is also well documented, but these agents should be prescribed with care, as long-term safety studies are still pending. In contrast, however, most of the antihistamines in the market have not been studied. Of the 40 antihistamines currently available, only 13 have undergone studies on pharmacokinetics and pharmacodynamics in children, Van Bever pointed out. And among the second-generation antihistamines, only four have been studied in children. "When we look at the second-generation antihistamines and we look at the safety studies, then you must conclude that only four antihistamines have been studied in preschool children: cetirizine, levocetirizine, loratidine, and desloratidine," he said. As for use in infants, only two-cetirizine and levocetirizine -have been closely studied, although there are also limited studies involving ketotifen. Van Bever said the studies on cetirizine and levocetirizine involved large groups and were appropriately designed to determine their safety and efficacy in children. He said that based on studies, cetirizine and levocetirizine are safe for young children-"and this for me is the most important." He added that these drugs have a short half-life, are cleared rapidly from the blood, and are best to use twice daily in a higher dose in young children. M |
