Two new linked studies on the effectiveness and safe dosing of theophylline nasal irrigation to treat COVID-19–related altered sense of smell have generated inconclusive results.The research, a phase 2 randomized, controlled clinical trial and a small, phase 1, open-label dose-escalation study, was published yesterday in JAMA Otolaryngology - Head & Neck Surgery.Theophylline relaxes and opens respiratory passages in the lungs and is used to prevent and treat shortness of breath, wheezing, and chest discomfort caused by asthma, emphysema, chronic bronchitis, and other conditions.
It may also promote neural olfactory signaling.Inconclusive benefit suggested by subjective findingsResearchers from Washington University in St.
Louis, Missouri, led the clinical trial involving 51 adult Missouri or Illinois residents with olfactory dysfunction persisting for 3 to 12 months after COVID-19 infection.
The trial was conducted from Mar 15 to Aug 31, 2021.Participants were mailed saline sinus-rinse kits and identical-appearing capsules containing either 400 milligrams (mg) of theophylline or a placebo consisting of 500 mg of lactose powder.