Vascular absorption of intravesical formalin in cyclophosphamide induced haemorrhagic cystitis

Haemorrhagic cystitis was induced in dogs by the administration of cyclophosphamide. The bleeding was stopped by intravesical instillation of Formalin. Vascular absorption of formaldehyde was determined by measurement of serum levels. Progressively increasing amounts in apparent relationship to the concentration of Formalin instilled into the bladder were found in all dogs. Higher serum levels were noted in animals with haemorrhagic cystitis induced by cyclophosphamide than in dogs with normal bladders. This study reinforces our clinical impression that formaldehyde is absorbed continuously through the wall of the urinary bladder in dogs and absorption is related to the concentration gradient. These kinetics should be kept in mind when treating patients with intravescial Formalin in order to prevent the systemic effect of the vascular absorption.