Mydriasis, or pupil dilation, can be caused by various drugs. Based on the provided references, here's a breakdown of the drug classes that can lead to mydriasis:
Drugs Causing Mydriasis
Certain classes of drugs can induce mydriasis by affecting the neurological systems responsible for controlling pupil size.
Stimulants
Stimulant drugs, particularly those that affect monoaminergic systems, often result in pupil dilation. Examples from the reference include:
- Amphetamines
- Cocaine
- MDMA
- Mephedrone
These drugs increase the activity of certain neurotransmitters which then activate the sympathetic nervous system leading to pupillary dilation.
Anticholinergics
Anticholinergic drugs work by blocking the action of acetylcholine at muscarinic receptors in the eye. This blockage prevents the iris sphincter muscle from contracting, which normally constricts the pupil; leading to dilation (mydriasis). The reference lists the following as anticholinergic drugs that can cause mydriasis:
- Diphenhydramine
- Atropine
- Hyoscyamine
- Scopolamine
These drugs are commonly found in over-the-counter and prescription medications as well as in some recreational settings. They counteract the parasympathetic nervous system’s influence on the pupillary muscles, causing them to relax and pupils to dilate.
Summary of Drugs Causing Mydriasis
| Drug Class | Examples | Mechanism of Action |
|---|---|---|
| Stimulants | Amphetamines, Cocaine, MDMA, Mephedrone | Increase monoaminergic neurotransmitters, activating the sympathetic nervous system. |
| Anticholinergics | Diphenhydramine, Atropine, Hyoscyamine, Scopolamine | Antagonize muscarinic acetylcholine receptors, blocking parasympathetic influence. |
