Increased levels of substance P in patients taking beta‐blockers are linked with a protective effect on oropharyngeal dysphagia

Background We have recently found a potential protective effect of beta‐blockers on oropharyngeal dysphagia (OD). The action mechanism by which beta‐blockers could wield this protective effect is unknown, but the neurotransmitter substance P (SP) could play a key role. The aim of this study was to analyze serum and saliva SP levels in patients taking beta‐blockers (TBB), and to explore its relationship with OD. Methods Adult (>50 year) patients TBB were randomly recruited from the primary care setting and 1:1 matched by age, sex, and Barthel Index (BI) with patients not taking beta‐blockers (NTBB). Serum and saliva samples were taken and analyzed for their SP levels using an enzyme‐linked immunosorbent assay (ELISA). Socio‐demographic and clinical variables were collected. Dysphagia was evaluated in all patients using the clinical volume‐viscosity swallow test (V‐VST). Key Results We studied 28 patients TBB (64.96 ± 7.31 years, 57.1% women, BI 99.6 ± 1.31, carvedilol‐equivalent dose 24.11 ± 18.12 mg) and 28 patients NTBB (65.61 ± 6.43 years, 57.1% women, BI 99.6 ± 1.31). SP serum levels were significantly higher in patients TBB (260.68 ± 144.27 vs 175.46 ± 108.36 pg/mL, P = .009) as were SP saliva levels (170.34 ± 146.48 vs 102.73 ± 52.28 pg/mL, P