Effects of pentoxifylline on olfactory sensitivity: a postmarketing surveillance study

To investigate the effect of pentoxifylline, an unspecific phosphodiesterase inhibitor, on olfactory function.

Longitudinal study.

Nineteen patients who received pentoxifylline to treat inner-ear conditions.

Evaluation of olfactory function (ie, odor threshold, odor discrimination, and odor identification) before and after administration of pentoxifylline and assessment of nasal airflow.

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.

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.