We gave all patients in group A an ACE inhibitor (imidapril
hydrochloride), 5 to 10 mg qd orally, and all patients in group B
received Ang II (losartan potassium), 50 to 100 mg qd orally. We
measured serum substance P before and 12 weeks after administration.
The mean serum substance P before drug administration was 26.5 pg/mL in
group A and 26.36 pg/mL in group B. After 12 weeks, symptomless
dysphagia improved in 23 of 32 patients in group A. In these 23
patients, the mean serum substance P was 82.91 pg/mL. In six patients,
symptomless dysphagia did not improve (mean serum substance P, 50.62
pg/mL) and in four of them, serum substance P was not increased (mean
serum substance P, 46.12 pg/mL). Imidapril hydrochloride was stopped in
the remaining patients because of excessive cough (mean serum substance
P, 109.83 pg/mL). On the other hand, in all 21 patients in group B,
symptomless dysphagia did not improve, and in all of them, serum
substance P did not increase (mean serum substance P, 30.49 pg/mL)
after 12 weeks (p < 0.0001).