[The use of the determination of plasma theophylline concentrations in the hospital].

BACKGROUND

The evaluation of the determination of plasmatic concentrations of theophylline (PCT) in clinical practice is scarce. An observational study was carried out with the aim of discerning the reasons why PCT determinations are requested, the theophyllinemias obtained and the attitude of the medical staff in a hospital.

METHODS

PCT determinations obtained in 113 patients over a period of 3 months were analyzed. Information concerning treatment and daily doses of theophylline, reasons for theophylline determination, apart from those included in the request for theophyllinemia determination, clinical history and treatment sheets were collected.

RESULTS

Treatment with theophylline had been indicated in 78 patients (69%) with chronic bronchitis, and 30 (26%) with asthma. All the patients received medication in addition to theophylline. Daily dosage (SD) was 734 (260) mg and the daily doses as to body weight (SD) was 11 (4) mg/kg/day. 188 DNPT were performed, however 22 (12%) were inadequate; of the remaining 166 PCT determinations 117 (69%) had been requested with no indication of insufficient clinical response, suspicion of undesirable effects or modifying factors of the pharmacokinetics of theophylline. The mean plasmatic concentration (SD) was 11.3 (7) micrograms/ml. PCT was infratherapeutic in 74 PCT determinations (44%), therapeutic in 73 (44%) and toxic in 19 (11%). Therapeutic concentrations were obtained in only 16 (35%) of the 45 patients in whom a second PCT determination had been carried out.

CONCLUSIONS

In this study scarce individualization in the indication of treatment and the doses of theophylline administered are observed. The reason for soliciting determination of theophyllinemia and dosage adjustment in terms of plasmatic concentrations are also commented upon.