Signal processing in the olfactory neuron could be influenced by inhibition of enzymes like phosphodiesterase. Pentoxifylline is a unspecific phosphodiesterase inhibitor. The hypothesis is that pentoxifylline could lead to increased sensitivity to odors.

Olfactory signal processing is conducted by a G-protein linked increase of intracellular concentration of adenosine 3´,5´-cyclic monophosphate (cAMP). In the cilia of olfactory sensory neurons (OSN) cAMP is degraded by phosphodiesterase 1C2 (PDE1C2). Inhibition of PDE1C2 could result in an increased response of OSN to chemical stimuli. Aim of the present prospective post-marketing surveillance study was to investigate the impact of pentoxifylline, an unspecific phosphodieasterase inhibitor, on olfactory function.

Inclusion Criteria:

• hyposmic or functionally anosmic patients TDI-score <31
• age: 18-50 years
• odor threshold: better than 1
• cause of smell loss: post traumatic, postinflammatory, idiopathic

Exclusion Criteria:

• normosmic patients,
• patients with contraindications for application of pentoxifylline
• patients that cannot give written agreement to the study
• patients under 18 years and over 50 years of age

hyposmic or functionally anosmic patients TDI-score <31; age: 18-50 years; odor threshold: better than 1; cause of smell loss: post traumatic, postinflammatory, idiopathic