Antimuscarinic drugs: traditional and potential new therapeutic agents

Measures of anticholinergic drug exposure, serum anticholinergic activity, and all-cause postdischarge mortality in older hospitalized patients with hip fractures

OBJECTIVES

To assess possible associations between anticholinergic drug exposure and serum anticholinergic activity (SAA) and their capacities to predict all-cause mortality in older hospitalized patients.

SETTING

Academic medical center.

PARTICIPANTS AND MEASUREMENTS

Data on clinical characteristics, full medication exposure, SAA, and 4 anticholinergic drug scoring systems (ADSSs: Anticholinergic Risk Scale [ARS], Anticholinergic Drug Scale, Anticholinergic Burden scale, and anticholinergic component of the Drug Burden Index) were collected in 71 older hospitalized patients (age 84 ± 6 years) awaiting surgical repair after hip fractures.

RESULTS

The median (range) SAA was 2.8 (1.1-4.9) pmol/mL. Age (ρ = 0.25, p = 0.03), Katz Index of Independence in Activities of Daily Living score (ρ = 0.39, p = 0.001), in-hospital delirium (ρ = 0.29, p = 0.01), preadmission cognitive impairment (ρ = 0.31, p = 0.01), and the number of nonanticholinergic drugs (n-NA, ρ = -0.27, p = 0.02) were associated with SAA. No significant associations were detected between ADSSs and SAA. Cognitive impairment (β = 2.1, 95% confidence interval [CI]: 0.7 to 2.5, p = 0.005) and n-NA (β = -0.3, 95% CI: -0.5 to -0.03, p = 0.03) were independently associated with SAA. Cognitive impairment (hazard ratio [HR]: 6.7, 95% CI: 1.1 to 40.3, p = 0.04) and higher ARS scores (HR: 2.2, 95% CI: 1.2 to 3.7, p = 0.006) independently predicted 3-month mortality whereas in-hospital delirium (HR: 3.6, 95% CI: 1.3 to 10.3, p = 0.02), living at home (HR: 0.2, 95% CI: 0.0 to 0.9, p = 0.03), and length of hospital stay (HR: 1.1, 95% CI: 1.0 to 1.2, p = 0.004) independently predicted 1-year mortality after adjustment for age, gender, and Charlson comorbidity index.

CONCLUSIONS

Cognitive impairment and n-NA, but not ADSSs, are independently associated with SAA in older hospitalized patients. The ARS score, together with cognitive impairment, in-hospital delirium, place of residence, and length of hospital stay, predicts all-cause mortality in this group.

Autoregulation of acetylcholine release from vagus nerve terminals through activation of muscarinic receptors in the dog trachea

1. The effects of pirenzepine and gallamine on the membrane and contractile properties of smooth muscle cells and on excitatory neuro-effector transmission in the dog trachea were investigated by means of microelectrode, double sucrose gap and tension recording methods. 2. Pirenzepine (10(-7) M) and gallamine (10(-5) M) had no effect on the resting membrane potential or the input resistance of the smooth muscle cells. 3. Pirenzepine (10(-10)-10(-9) M) and gallamine (10(-7) M) enhanced the amplitude of twitch contractions evoked by field stimulation in the combined presence of indomethacin (10(-5) M) and propranolol (10(-6) M). At higher concentrations pirenzepine (10(-8) M) inhibited the twitch contractions in a dose-dependent manner. Both pirenzepine and gallamine in doses over 10(-7) and 10(-5) M, respectively, reduced muscle tone. 4. Pirenzepine (10(-10)-10(-9) M) and gallamine (10(-7) M) enhanced the amplitude of excitatory junction potentials (e.j.ps) evoked by field stimulation (single or repetitive stimulation). However, a high concentration of pirenzepine (10(-8) M) reduced the amplitude of e.j.ps. In parallel with its action on e.j.ps, pirenzepine (over 10(-9) M) reduced the response of smooth muscle cells to acetylcholine (ACh), in a dose-dependent manner. Gallamine (5 X 10(-5) M) markedly enhanced the amplitude of e.j.ps but also reduced the response of muscle cells to ACh. 5. ACh (10(-10)-10(-9) M) inhibited twitch contractions evoked by field stimulation, with a slight increase of resting tension. 6. Gallamine enhanced the summation of e.j.ps during repetitive field stimulation at a high frequency (20 Hz), but was without effect on the depression phenomena of e.j.ps observed during double stimulus experiments at different time intervals (5-60 s). 7. These results indicate that both pirenzepine and gallamine have dual actions on pre- and post-junctional muscarinic receptors in dog tracheal tissue. At low concentrations both agents potentiate excitatory neuro-effector transmission, presumably due to enhancement of release of ACh from vagal nerve terminals through blockade of a negative auto-regulatory process activated by endogenous ACh. At higher concentrations, these agents inhibit the response of smooth muscle cells to ACh through post-junctional muscarinic receptors and relaxation of the muscle tissue occurs.