Background and importance The optimal dose of anticancer drugs is the one that produces the maximum antitumuor effect associated with an acceptable level of toxicity. Low doses will be ineffective against cancer, while high doses will produce intolerable toxicity, especially in children.

Aim and objectives The purpose of this study was to evaluate and analyse the compliance of dosages related to children anticancer drugs underdose or overdose.

Material and methods It was a retrospective study based on the recalculation of doses of 270 prescriptions of cytotoxic drugs in the paediatric hemato-oncology department of Rabat.

Results The anticancer drugs most often used are vincristine (21.5%), cyclophosphamide (14.4%), mercaptopurine (10%), methotrexate (7.8%), etoposide (6.7%), other drugs (39.6%).

Of 270 recalculated doses of anticancer drugs, 67.8% were compliant, 27.4% were underdosed and 4.8% were overdosed.

45.1% of deviation cases were not justified, 33.3% of the doses were rounded off, 9.6% represented the maximum that can be administered, 8.6% were calculated according to weight and not by body surface area, and 3.2% were for children in denutrition.

Concerning the recorded underdoses, the maximum deviation noted was 47.3% with an average of 14.7% compared to the therapeutic dose. For the overdoses, the maximum deviation was 41.6% with an average of 4% compared to the therapeutic dose.

Based on the number of drugs with anomalies, the most underdosed drugs were cyclophosphamide (17.5%) followed by vincristine (16.2%) then etoposide (13.5%). Conversely, the most overdosed drugs were mercaptopurine (23%) followed by methotrexate (15.3%).

Based on the average deviation between prescribed and therapeutic doses, the most underdosed drugs were high-dose methotrexate (35%), mercaptopurine (28%) and adriamycin (26%), whereas the most overdosed drugs were vincristine (42%), mercaptopurine (9%) and high-dose methotrexate (6%).

The interventions made by pharmacists in cases of dose deviations were to recalculate the prescribed doses and inform the prescribing physician either to detect a possible error of overdosing in order to correct it or to look for the reason for underdosing if this is not mentioned on the chemotherapy preparation sheet.

Conclusion and relevance According to the results, almost half of the anomalies are unjustified, hence the importance of pharmaceutical validation of chemotherapy orders and dose compliance verification by the hospital pharmacist to better manage anticancer drugs risks.

Conflict of interest No conflict of interest