Some physicians, recommend divided dose to minimize the gastrointestinal side effects, while the other physicians, recommend a single daily dose for better compliance.
Research studies showed that the efficacy of carbimazole (Neomercazole) when taken as a single dose per day or in divided doses, is similar or comparable. The single daily dose of Neomercazole is found to be superior to "Divided-dose" method as it is associated with better compliance. It may be difficult for the patients to remember taking the divided doses. Sometimes, patient may forget to take the evening dose. So single daily dose is especially effective for those patients who find it difficult to remember the timings of divided dose.
Single daily dose of Carbimazole is superior to divided dose. As single daily dose has the similar efficacy as that of divided dose, and it is associated with better compliance of the patient to his medications.
Single daily dose of Carbimazole in treatment of hyperthyroidism: Gupta SK 1992 Link: https://www.ncbi.nlm.nih.gov/pubmed/1302580