Neostigmine for the treatment of gastrointestinal atony: a report of one case

Opioid-induced constipation: a narrative review of therapeutic options in clinical management

Pain therapy often entails gastrointestinal adverse events. While opioids are effective drugs for pain relief, the incidence of opioid-induced constipation (OIC) varies greatly from 15% to as high as 81%. This can lead to a significant impairment in quality of life, often resulting in discontinuation of opioid therapy. In this regard, a good doctor-patient relationship is especially pivotal when initiating opioid therapy. In addition to a detailed history of bowel habits, patient education regarding the possible gastrointestinal side effects of the drugs is crucial. In addition, the bowel function must be regularly evaluated for the entire duration of treatment with opioids. Furthermore, if the patient has preexisting constipation that is well under control, continuation of that treatment is important. In the absence of such history, general recommendations should include sufficient fluid intake, physical activity, and regular intake of dietary fiber. In patients of OIC with ongoing opioid therapy, the necessity of opioid use should be critically reevaluated in terms of an with acceptable quality of life, particularly in cases of non-cancer pain. If opioids must be continued, lowering the dose may help, as well as changing the type of opioid. If these measures do not suffice, the next step for persistent OIC is the administration of laxatives. If these are ineffective as well, treatment with peripherally active μ-opioid receptor antagonists should be considered. Enemas and irrigation are emergency measures, often used as a last resort.

Efficacy and Safety of Subcutaneous Neostigmine for Ileus, Acute Colonic Pseudo-obstruction, or Refractory Constipation

Background: Neostigmine is traditionally administered intravenously for treatment of acute colonic pseudo-obstruction (ACPO), though use is associated with administration constraints and adverse effects. Objective: To evaluate whether an alternative route of administration for neostigmine via subcutaneous (SQ) delivery is safe and effective in a broad cohort of medical and surgical patients. Methods: This multicenter, retrospective observational study included adult patients administered SQ neostigmine for ileus, ACPO, or refractory constipation. Efficacy indicators were time to first bowel movement (BM) following initiation of the medication, total SQ neostigmine dose administered to produce a BM, and administration of a rescue intervention to produce a BM. Safety events evaluated were cardiac arrest, bradycardia, bronchospasm requiring intervention, nausea requiring intervention, or severe salivation, lacrimation, or diarrhea. Results: A total of 182 patients were eligible for inclusion. The most commonly utilized dosing strategy of neostigmine was 0.25 mg SQ 4 times daily. The median time to first BM following initiation of SQ neostigmine was 29.19 hours (interquartile range = 12.18-56.84) with a median dose administered before first BM of 1.25 mg. Three patients (1.65%) experienced an adverse drug event leading to drug discontinuation, with 2 developing bradycardia that resolved with drug discontinuation alone. Conclusions: SQ neostigmine may be reasonable for management of ileus, ACPO, or refractory constipation, though use should be avoided in patients with new-onset heart block, a history of second-degree heart block, or following bowel resection with primary anastomosis. Despite the low incidence of adverse drug events observed, monitoring for bradycardia with telemetry may be considered.

Cholinergic interactions between donepezil and prucalopride in human colon: potential to treat severe intestinal dysmotility

BACKGROUND AND PURPOSE

Cholinesterase inhibitors such as neostigmine are used for acute colonic pseudo-obstruction, but cardio-bronchial side-effects limit use. To minimize side-effects, lower doses could be combined with a 5-HT4 receptor agonist, which also facilitates intestinal cholinergic activity. However, safety concerns, especially in the elderly, require drugs with good selectivity of action. These include the AChE inhibitor donepezil (used for Alzheimer's disease, with reduced cardio-bronchial liability) and prucalopride, the first selective, clinically available 5-HT4 receptor agonist. This study examined their individual and potential synergistic activities in human colon.

EXPERIMENTAL APPROACH

Neuronally mediated muscle contractions and relaxations of human colon were evoked by electrical field stimulation (EFS) and defined phenotypically as cholinergic, nitrergic or tachykinergic using pharmacological tools; the effects of drugs were determined as changes in 'area under the curve'.

KEY RESULTS

Prucalopride increased cholinergically mediated contractions (EC50 855 nM; 33% maximum increase), consistent with its ability to stimulate intestinal motility; donepezil (477%) and neostigmine (2326%) had greater efficacy. Concentrations of donepezil (30-100 nM) found in venous plasma after therapeutic doses had minimal ability to enhance cholinergic activity. However, donepezil (30 nM) together with prucalopride (3, 10 μM) markedly increased EFS-evoked contractions compared with prucalopride alone (P = 0.04). For example, the increases observed with donepezil and prucalopride 10 μM together or alone were, respectively, 105 ± 35%, 4 ± 6% and 35 ± 21% (n = 3-7, each concentration).

CONCLUSIONS AND IMPLICATIONS

Potential synergy between prucalopride and donepezil activity calls for exploration of this combination as a safer, more effective treatment of colonic pseudo-obstruction.