A method for administering an active agent to a pleura of a patient includes preparing a composition including a foamable liquid and the active agent, incorporating a gas into the foamable liquid to create a foam containing the active agent, introducing the foam into a pleural cavity of the patient defined by the pleura, and contacting the pleura with the foam. A method of pleurodesis includes introducing a composition into a pleural cavity defined by pleurae of a patient, the composition including a foamable liquid and an active agent capable of causing inflammation and/or adhesion of the pleurae. A composition for treating a pleura of a patient includes a liquid component including a biocompatible composition having a viscosity which increases in response to an increase in temperature, and an active agent capable of causing inflammation and/or adhesion of the pleura.