The ability of undergraduate nursing students to calculate the drug dose correctly and consistently has been a concern for a long time. This was a pre-post interventional study that had evaluated the ability of nursing students to calculate drug dose at a tertiary teaching hospital in Eastern Nepal. Findings from this study confirm that more than most of the nursing students were unable to perform drug dose calculations competently in the pre-test and after the intervention, there was significant increase in the ability.

There was statistically significant improvement in their awareness regarding importance of double checking of own drug dose calculations and the necessity to check the calculated dose with a second person during the dose calculation. The increased awareness certainly enhances the accuracy in drug dose calculation and help to prevent dug dose related errors. It is of utmost importance to inculcate such culture at the beginning of the nursing education so that they can practice it for rest of their professional career.

Our study showed that the mean score of the students was more than 50% both in pre-test and post-test. Brown found similar results in which the mean score was 75% [14]. No one achieved 100% score in pretest and only one-fifth of the students scored 100% in post-test. Similar findings were also reported in other studies [6, 15]. Errors in drug dose calculation occur either because of the numerical inability of the students to perform basic functions such as addition, subtraction, multiplication, division and use of decimals and fractions or due to their inability to conceptually extract the correct information from the drug dose calculation problems in order to set up the mathematical calculations needed [16]. The students who perform poorly on the written tests on drug dose calculations are assumed to have poor skills in practice. Therefore, the nurse educationist should also focus on the education of nursing students regarding accurate drug dose calculations.

Drug dose calculation ability of the students was poor in the pretest in our study which improved in the post-test after the intervention. Other researches also showed that the ability of drug dose calculation of nursing students was poor [16, 17]. Similarly majority of the nursing students failed on drug calculation test at a 90% pass level in other researches as well [18, 19]. The students who scored less than 90% may benefit from frequent education and skill test on drug dose calculation that might help to improve their skills in the area and to decrease the potential patient safety issues. Frequent and mandatory drug calculation modules, both practical and theoretical, should be included in the nursing curriculum from 1st to 4th year which will reinforce the knowledge and skill and make them more competent. Higher secondary education with marks more than 75% was associated with better score among the students in our study. Similar findings were also reported by Grandell-Niemi et al [19]. Therefore previous knowledge and experience on mathematical skills should be considered before planning and implementing effective modules on drug dose calculation ability among nursing students.

The educationist should address mathematical skills and concepts, linking numeracy competency with meaning and context and teaching drug calculation formulae and practical calculation examples should be provided for developing the competency in drug dose calculations [20, 21]. We have to revise effective teaching and learning strategies to support and facilitate nursing students to learn this skill and make them competent [21]. Perhaps there is a need for collaboration between the Nursing Council of Nepal and other relevant authority to establish a core set of competencies and good nursing practice for clinical education of nursing health care professionals. It would be more practical to include drug dose calculation related objective problems during service entry examination of nurses. Researches need to be conducted frequently to check the competencies in drug dose calculation of the nursing students as well as nursing personals. With the advent of more accessible and affordable computer and mobile technology, more use of online materials should be encouraged to enhance mathematical skills among nurses.

Our study had some limitations also. The sample size of the study was small. The arithmetical, conceptual and computational errors were not evaluated. Being a single-center study, the findings may not be generalized to other nursing students studying at different institutions.