Effects of Pentoxifylline on Olfactory Sensitivity A Postmarketing Surveillance Study

Objective: To investigate the effect of pentoxifylline, an unspecific phosphodiesterase inhibitor, on olfactory function. Design: Longitudinal study. Patients: Nineteen patients who received pentoxifylline to treat inner-ear conditions. Main Outcome Measures: Evaluation of olfactory function (ie, odor threshold, odor discrimination, and odor identification) before and after administration of pentoxifylline and assessment of nasal airflow. Results: Administration of pentoxifylline had no significant effect on nasal airflow (P =. 84). After administration of pentoxifylline, patients demonstrated a decrease in odor threshold toward lower odor concentrations (P =. 01). The odor threshold shift after administration of pentoxifylline was more pronounced in younger patients than in older patients (correlation between age and change in odor threshold: r = -.72; P =. 001). No such changes were observed for suprathreshold olfactory tasks (odor discrimination and odor identification). Six of the 19 patients were found to have hyposmia. Two patients demonstrated a clinically significant decrease in odor threshold after drug administration. Conclusions: The present findings may indicate a role for pentoxifylline in the treatment of olfactory loss. Double-blind, placebo-controlled studies are needed to verify whether pentoxifylline can improve olfactory sensitivity in patients with olfactory disorders.