The present invention provides methods for determining the selectivity of an anesthetic for an anesthetic-sensitive receptor by determining the molar water solubility of the anesthetic. The invention further provides methods for modulating the selectivity of an anesthetic for an anesthetic-sensitive receptor by altering or modifying the anesthetic to have higher or lower water solubility. The invention further provides methods of inducing anesthesia in a subject by administering via the respiratory pathways (e.g., via inhalational or pulmonary delivery) an effective amount of an anesthetic compound identified according to the present methods.