ABSTRACT
Significant differences in the rate and extent of absorption exist between slow release theophylline (SRT) preparations. The pharmacokinetic characteristics of Xanthium were compared with those of Theo-Dur in twelve Thai children with stable persistent asthma by randomized, double blind, crossover study. Serum theophylline concentrations (STCs) were determined by fluorescence polarization immunoassay. The pharmacokinetic parameters were estimated by using a computer program (Topfit 2.0). The STCs, at steady state after different doses, were predicted by using the modified Wagner-Nelson Equation. The mean resident time (MRT) and apparent T1/2 were significantly larger for Xanthium, but the Cmax and AUC0-infinity of Xanthium were significantly lower than those of Theo-Dur. The Frel of Xanthium was 80.1% relative to Theo-Dur. The appropriate dosing interval of both preparations for Thai children was twice a day.
Subject(s)
Administration, Oral , Adolescent , Area Under Curve , Asthma/drug therapy , Child , Chronic Disease , Cross-Over Studies , Delayed-Action Preparations , Double-Blind Method , Female , Fluorescence Polarization Immunoassay , Half-Life , Humans , Male , Software , Thailand , Theophylline/administration & dosageABSTRACT
The Phase One International Study of Asthma and Allergies in Childhood (ISAAC) was developed for geographical and temporal comparisons of the prevalence and severity of asthma and allergic diseases in childhood within and between countries. In Thailand, a study was carried out in Bangkok and this is a further study undertaken in Chiang Mai. Using the ISAAC questionnaire, schoolchildren of two age groups were studied: 6-7 years old (n = 3,828) and 13-14 years old (n = 3,927). The data were entered and analyzed using the Epi-info computer program. The prevalence over the past 12 months, in 6-7 and 13-14 years olds, respectively, are as follows; wheezing, 5.5% and 12.6%; rhinitis, 18.5% and 38.3%; rash at flexural areas, 12.9% and 10.7%. The prevalence of these three conditions was found to be close to, but slightly lower than, that from Bangkok, except for eczema in older children.
Subject(s)
Adolescent , Asthma/epidemiology , Electronic Data Processing , Child , Eczema/epidemiology , Female , Humans , International Cooperation , Male , Multicenter Studies as Topic , Prevalence , Surveys and Questionnaires , Rhinitis/epidemiology , Seasons , Thailand/epidemiologyABSTRACT
Nasal reactivity to histamine was determined in patients with perennial allergic rhinitis and in control subjects. A histamine titration method delivered by a metered dose pump was used. Stuffiness, itching, and the number of sneezes were recorded, nasal secretions measured, and nasal airway resistance was recorded by active anterior rhinomanometry. Increased nasal reactivity to histamine was observed among rhinitic patients and inversely correlated with the severity of nasal symptoms. A 3-fold increase of post-saline nasal airway resistance (NAR) best differentiated the nasal responses to histamine in rhinitic patients from those in control subjects. A histamine dose of < or = 2.5 microg provoked a 3-fold increase in NAR, strongly suggesting moderate or severe symptomatic rhinitis in most cases. Nasal provocation techniques might be a useful tool for objectively assessing disease severity and response to treatment in perennial allergic rhinitis.