class IIb if they are intended for long-term use, except if they are used in the oral cavity as far as the pharynx, in an ear canal up to the ear drum or in the nasal cavity and are not liable to be absorbed by the mucous membrane, in which case they are classified as class IIa.
in aicme IIb má beartaíodh iad lena n-úsáid go fadtéarmach, seachas má úsáidtear iad i gcuas an bhéil chomh fada leis an bhfaraing, i gcanáil chluaise suas go tiompán na cluaise nó i gcuas na sróine agus nach dóigh go n-ionsúfaidh an tseicin mhúcasach iad, agus sa chás sin tá siad aicmithe mar aicme IIa.