Tag: Acetylcholine

According to the National Institutes of Health, atropine is a potent antimuscarinic agent used to treat conditions like bradycardia and organophosphate poisoning by blocking the neurotransmitter acetylcholine. This article will delve into the core mechanism of action, answering the question: what is the main action of atropine?

According to the American Association of Poison Control Centers, tens of thousands of antihistamine exposures with anticholinergic effects are reported annually, highlighting the prevalence of these drugs. The range of clinical manifestations is broad, making it crucial to understand **what are the side effects of anticholinergic toxicity**.

As of 2022, an estimated 4.2 million Americans live with glaucoma, a leading cause of irreversible blindness [1.7.2, 1.7.1]. A foundational question in its treatment is, 'What cholinergic drug causes miosis and is used in the treatment of glaucoma?' The answer is primarily Pilocarpine [1.2.2].

More than 70 years ago, cholinesterase inhibitors were introduced as a way to treat glaucoma by lowering intraocular pressure (IOP). This class of medication is known for its indirect action, which helps increase the outflow of fluid from the eye through a specific biological pathway controlled by acetylcholine.

According to preclinical studies, the atypical antipsychotic olanzapine can produce a significant, dose-dependent increase in extracellular acetylcholine (ACh) release in brain regions such as the hippocampus. This effect runs counter to the drug's known anticholinergic properties, presenting a pharmacological paradox that explains both its therapeutic benefits and some side effects.

Approximately 27% of patients using anticholinergic medications experience constipation, a primary side effect of this drug class [1.2.2]. So, what are the effects of anticholinergic drugs on the gut? They primarily work by inhibiting the neurotransmitter acetylcholine, leading to significant changes in digestive function [1.2.2].

A 2021 review noted that many medications, not just primary anticholinergics, can have anticholinergic activity, which raises the important question: are blood pressure medications anticholinergic, or do they simply cause similar side effects? The answer is not straightforward and requires a deeper look into pharmacology.

Physostigmine is a natural alkaloid originally extracted from the Calabar bean, used historically as an ordeal poison and later for its medicinal properties. Today, its primary classification is a reversible acetylcholinesterase inhibitor, which explains its role as an antidote for overdoses involving anticholinergic substances.

First isolated from the Calabar bean in 1863, physostigmine is a cholinesterase inhibitor with a long history in medicine. In response to the question, "Does physostigmine dilate or constrict?" the answer is a definitive constriction, and understanding its underlying pharmacology is key to grasping its clinical applications.

Contrary to the common misconception, acetylcholine does not cause pupils to dilate. In fact, this vital neurotransmitter plays the central role in causing the pupils to constrict, a process known as miosis. This action is a key function of the body's parasympathetic nervous system, ensuring the eye can regulate the amount of light it receives.