Effects of neostigmine and glycopyrrolate on pulmonary resistance in spinal cord injury

Preliminary findings in subjects with spinal cord injury (SCI) suggest that neostigmine administered intravenously increases colonic tone, increases colonic contractions, and facilitates bowel evacuation. Of concern are potential pulmonary side effects, including an increase in airway secretions and bronchospasm. The objectives of the study were to determine the effects of intravenously administered neostigmine or neostigmine combined with glycopyrrolate on forced oscillation indices in persons with SCI. Pulmonary resistances at 5 Hz (R5) and 20 Hz (R20) were measured with the use of an impulse oscillation system (IOS) in 11 subjects with SCI. Values were obtained before and after the intravenous administration of 2 mg of neostigmine alone and, on a separate day, before and after the administration of 2 mg of neostigmine combined with 0.4 mg of glycopyrrolate. Baseline R5 and R20 values before neostigmine correlated significantly with baseline values before neostigmine combined with glycopyrrolate. Following neostigmine, mean R5 values increased 25% and mean R20 values increased 18%. Following neostigmine combined with glycopyrrolate, mean R5 values fell 9% and mean R20 values fell 7%. In summary, baseline IOS values obtained on 2 different days were highly reproducible in this population. Neostigmine alone induced significant bronchoconstriction, whereas neostigmine combined with glycopyrrolate caused bronchodilation.