The stability
tests revealed that the physio-chemical properties of the dispersible 75mg
aspirin tablets weren’t maintained after repackaging into multi dose compliance
aids over 5 the week period.

A weight
uniformity test was conducted to ensure accurate and consistent dosage
form.  It was shown that there was a
change in the mean weight of the tablets from 148.29 ± 0.0094 mg to 149.54 ±
0.0169 mg, with a 0.84% increase. The masses complied with the British
Pharmacopoeial standards as they were between 80 and 250 mg with a coefficient
variance of less than 7.5%.8 Despite the requirements being met,
this small but significant weight increase may be indicative of an uptake of
humidity from the environment and a permeation of moisture through the compliance
aid. Aspirin is hygroscopic9 and is rapidly hydrolysed to salicylic
acid its degradant on exposure to moisture. According to the British
Pharmacopeia (BP), the limit of salicylic acid (SA) content within a
dispersible formulation is 3%10. Hydrolysis of aspirin may cause
product degradation, compromising bioavailability and reducing efficacy of the
drug. The pharmacist must consider whether the degradation of the active
pharmaceutical ingredient (API) will result in sub-therapeutic or toxic affect,
with potentially serious implications for the patient. It is the responsible
pharmacists’ duty to guarantee the safe supply of medicines.

A chemical titration
was used determine the content of aspirin. Before repackaging the amount of aspirin
was found to be 69.48mg which then decreased to 69.22mg. In both batches the
aspirin content failed to meet BP requirements as they weren’t within 95% -105%
of the labelled amount of 75mg11. Again, this could be due to
moisture uptake and hydrolysis, resulting in a reduction of the API and reduced
therapeutic efficacy. This may compromise patient safety, resulting in sub
therapeutic dosing. However, the values may not be accurate due to poor
titration technique and human error whilst reading the titre values. Although salicylic
acid content wasn’t tested, when weight gain is linked to water absorption the
physiochemical properties may be altered and the concentration of degradant may
increase12. A study on aspirin 300mg dispersible tablets repackaged
as whole and split tablets, demonstrated significant changes in the SA content.
When comparing with original packaging, a greater percentage of SA was present
in the tablets stored under different conditions. The tablets had swelled,
become discoloured and disintegrated easily, highlighting that both temperature
and moisture accelerate degradation13. Physical appearances are
important as alteration may discourage patients from administration, leading to
compliance issues which may be a safety issue. In future, SA and aspirin
content could be analysed using high pressure liquid chromatography (HPLC) for
increased precision and accuracy14.  Regarding weights, the variances may be down
to error of the balance. It may also be caused by the non-uniformity in the particle size
distribution and bulk densities of the tablets in their compression during
manufacturing18.