Variability in tablet fragment weights when splitting unscored cyclobenzaprine 10 mg tablets.

OBJECTIVE

To determine the weight variation and calculated dosing variability of tablet fragments upon splitting unscored cyclobenzaprine hydrochloride 10 mg tablets using two common tablet splitting devices.

DESIGN

Comparative pharmaceutics study.

SETTING

Pharmacy school laboratory.

PARTICIPANTS

Not applicable.

INTERVENTIONS

Unscored cyclobenzaprine hydrochloride 10 mg tablets from one generic manufacturer were split with a tablet splitter or a kitchen knife by a licensed pharmacist and two doctor of pharmacy students (n = 15 tablets for each method per participant).

MAIN OUTCOME MEASURES

Fragment weights (FWs) were compared with the theoretical weights (TWs), which were calculated as one half of the mean weight of the tablets used in each part of the experiment; means, relative standard deviations (RSDs), and percentages of TW were also calculated.

RESULTS

The mean weight before splitting the 45 tablets with the tablet splitter was 136.6 +/- 2.1 mg (TW = 68.3 mg). The mean FW after splitting was 67.9 +/- 7.9 mg. The RSD of 11.6% corresponded to a range of 69.4% to 130.2% of the TW and an estimated drug content of the split fragments between 3.47 mg and 6.51 mg. The mean weight before splitting the 45 tablets cut with a kitchen knife was 136.6 +/- 2.0 mg (TW = 68.3 mg). The mean FW was 68.0 +/- 15.7 mg with a RSD of 23.2%, corresponding to a range of 49.9% to 149.5% of the TW and an estimated drug content of the split fragments between 2.49 mg and 7.48

CONCLUSION

Tablet fragments obtained after splitting this generic cyclobenzaprine 10 mg product varied considerably in weight and estimated drug content. Accordingly, splitting cyclobenzaprine 10 mg tablets to achieve 5 mg doses could result in unpredictable dosing and therapeutic response.