A Simple Method to Measure Plasma Levels of Propafenone with Fluorescence Detection

Extemporaneous suspension of propafenone: attending lack of pediatric formulations in Mexico

BACKGROUND

Physicians have frequently encountered difficulties when prescribing drugs not available in doses suitable for pediatric age groups. Furthermore, children have difficulty swallowing tablets. This study aimed to determine the stability of an oral propafenone suspension made from commercial tablets with a syrup vehicle and to establish its reliable use with children.

METHODS

An extemporaneous suspension of propafenone 1.5 mg/ml was prepared with commercial tablets. Its physicochemical and microbiologic stability was established by constant monitoring during 90 days at room temperature (15 +/- 5 degrees C) and at refrigeration (3-5 degrees C). Plasma levels of propafenona were measured in two children with supraventricular tachycardia at steady state.

RESULTS

The suspension was stable, maintaining its original physicochemical and microbiologic properties. Moreover, no apparent changes in color or odor were observed. Plasma levels of propafenone in patients demonstrated therapeutic concentrations after they had taken the suspension, with no unwanted outcome.

CONCLUSIONS

The conservation of both physicochemical and microbiologic stability of the suspension represents an option for the administration of propafenone to children.

Bioavailability of an extemporaneous suspension of propafenone made from tablets

Propafenone is an effective antiarrhythmic agent used in children, while in Mexico no specific formulation for children is available, which causes errors in adequate dosage. The aim of this study was to determine the bioavailability of a suspension prepared extemporaneously using commercial tablets of propafenone. The bioavailability was determined in two groups of rabbits (n = 8): the first group received a single intravenous dose of 2 mg/kg of propafenone; the second was orally administered an extemporaneous suspension of propafenone prepared from commercial tablets. Blood samples were drawn at several times during the next 24 h and analysed by HPLC to determine drug levels. The extemporaneous suspension was tested previously with satisfactory results regarding physicochemical and microbiologic stability. The area under the curve (AUC) for the i.v. route was 5600.6 ng/ml.h and for oral administration the AUC was 3327.6 ng/ml.h. The bioavailability was calculated at 59.41%. These results are consistent with previous reports for solid dosage forms. The propafenone suspension prepared extemporaneously using commercial tablets is bioavailable using an animal model; nevertheless, it is necessary to carry out human studies either in volunteers or in patients to confirm these results.