Adjusting the dose in paediatric care: dispersing four different aspirin tablets and taking a proportion

Abstract

Objectives: When caring for children in a hospital setting, tablets are often manipulated at the ward to obtain the right dose. One example is manipulation of tablets containing the slightly water-soluble substance aspirin, used in paediatric care as an antiplatelet agent. The evidence base, however, for choosing certain tablet formulations and manipulation methods over others for extraction of proportions is lacking. The aim of this study was to investigate the effect of tablet formulation and manipulation technique on the dose accuracy and precision attained when dispersing different commercially available aspirin tablets and extracting a small proportion suitable for children.

Methods: The manipulation methods investigated simulated those observed in the paediatric clinic. Four tablet formulations-one chewable, one conventional and two dispersible-were dispersed in 10 mL water in a medicine measure. On (1) passive dispersion, (2) mixing by stirring with the syringe, or (3) stirring and pumping the dispersion in and out of the syringe, respectively, proportions (1 mL or 2 mL) were extracted and the doses recovered were determined using a validated UHPLC (ultra high-pressure liquid chromatography) method.

Results: Fractions from the four different dispersed aspirin tablet formulations varied from 99% to 3% of that intended with the lowest degree of mixing, and from 96% to 34% of that intended with the highest degree of mixing. Only the dispersible tablets gave average doses within 20% of the intended dose.

Conclusions: Fraction extraction from dispersed aspirin tablets only gave doses within 20% of intended for the dispersible tablets, and then only for some of the manipulation methods: 'passive dispersion' for the 75 mg dispersible tablet and 'stirring and pumping' for the 300 mg dispersible tablet. The tablets not intended for dispersion gave unsatisfactory results, outside 20%, regardless of manipulation method. The findings underline the importance of considering both tablet formulation and dose extraction technique when manipulations are required.

Keywords: clinical pharmacy; dispensing forms; drug administration (others); drug formulation; paediatrics; pharmaceutical excipients.

Figure 1

The four aspirin tablets upon passive dispersion in 10 mL purified water for 3 minutes. From left to right: DispersibleAspirin (75 mg), Bayer Chewable (81 mg), Disprin (300 mg), Aspirin (500 mg). Zones 1, 2 and 5 are marked Z 1, Z 2 and Z 5, respectively.