Punch, P.I., Costa, N.D., Edwards, M.E.&Wilcox, G.E. The release of insoluble antibiotics from collagen ocular insertsin vitroand their insertion into the conjunctival sac of cattle.J. vet. Pharmacol. Therap.10, 37–42.The release rate of procaine penicillin, erythromycin and erythromycin estolate from soluble and insoluble collagen films was investigatedin vitroto develop an ocular insert for the treatment of infectious bovine keratoconjunctivitis. The release rate and duration of release varied according to the selection of antibiotic and vehicle. The combination of erythromycin estolate and soluble collagen produced the most sustained drug‐delivery system. However, due to the inappropriate physical properties of collagen and poor retention of ocular inserts, it was considered that the development of an antibiotic‐impregnated collagen ocular insert requires further investig