The present invention is directed to devices and methods for administering at least one effective dose of at least one therapeutic substance to at least one of the maxillary sinuses of a patient in need thereof. Alternate embodiments may comprise administration of the at least one effective dose of at least one therapeutic substance to both maxillary sinuses, where the administered therapeutic substance(s) are either the same or differ from sinus to sinus. Still further alternative embodiments may comprise more than an initial effective dose administered to a patients maxillary sinus(es), so that the therapeutic substance may be delivered over time, thereby requiring a larger dose be deposited within at least one of the maxillary sinuses so that the maxillary sinus(es) serve as a therapeutic substance depot for long-term release to the target structure(s).
