PNS antagonists(anticholinergics)

What are the four classic side effects of anticholinergic drugs, summarized by the poem "Can't See, Can't Pee, Can't Spit, Can't Poop"?

• Can't See: Blurred vision (due to pupil dilation/cycloplegia)

• Can't Pee: Urinary retention

• Can't Spit: Dry mouth

• Can't Poop: Constipation

What are two therapeutic uses of anticholinergics based on their effects?

1. Asthma/COPD: Cause bronchodilation.

2. Parkinson's Disease: Help reduce tremors and rigidity.

What are two important systemic effects of anticholinergics?

1. Cardiovascular: Large doses cause tachycardia (increased heart rate).

2. Thermoregulation: Cause decreased sweating, leading to heat intolerance and risk of heat stroke.

How is Scopolamine most commonly administered and for what purpose?

It is a transdermal patch placed behind the ear to prevent and treat severe motion sickness.

Why might Scopolamine be given before surgery?

To reduce salivary and bronchial secretions, which helps prevent aspiration during the procedure.

How is Scopolamine used in end-of-life care?

It helps manage the "death rattle" by drying respiratory secretions, making breathing more comfortable for the dying patient.

What are the two main uses for Benztropine?

1. To treat Parkinson's disease (reduces tremors and rigidity).

2. To treat drug-induced extrapyramidal symptoms (EPS) caused by antipsychotic medications.

What is a critical, emergency use for Atropine?

To treat symptomatic bradycardia (a slow heart rate causing low blood pressure and fainting).

Why is Atropine given before surgery?

To decrease salivary and bronchial secretions, reducing the risk of aspiration during the procedure.

What is the primary use for Tolterodine?

To treat overactive bladder (it reduces urinary urgency and frequency by relaxing the bladder muscle).

What drug class is Ipratropium and what does it treat?

It is an anticholinergic bronchodilator used to treat Asthma and COPD.

How does Ipratropium differ from a fast-acting bronchodilator like Albuterol?

It has a slower onset of action but a longer duration of effect.

Why are anticholinergics absolutely contraindicated in glaucoma?

They cause pupil dilation (mydriasis), which can increase intraocular pressure and cause blindness in patients with narrow-angle glaucoma.

Why are anticholinergics dangerous for patients with Myasthenia Gravis?

Myasthenia Gravis is treated with cholinergic agonists to improve muscle strength.

• Anticholinergics would block this effect, worsening muscle weakness and potentially causing respiratory paralysis.

Name two GI/GU conditions worsened by anticholinergics.

1. Paralytic ileus or GI obstruction (decreases motility further).

2. Urinary retention (relaxes the bladder and tightens the sphincter).

3. GERD (relaxes the lower esophageal sphincter, worsening reflux).

Why must anticholinergics be used with caution in patients with heart failure?

They can cause tachycardia (increased heart rate), which puts extra strain on the heart.

What are potential central nervous system (CNS) side effects?

Hallucinations, confusion, insomnia, and nervousness (especially in older adults).

What is the risk of taking anticholinergics with other drugs like antihistamines or TCAs?

Additive anticholinergic effects, significantly increasing the risk and severity of side effects like dry mouth, constipation, urinary retention, and confusion.

What is the classic mnemonic for the symptoms of anticholinergic overdose?

• Mad as a hatter: Confusion, hallucinations

• Red as a beet: Flushing

• Hot as a hare: Fever (hyperthermia)

• Dry as a bone: Dry skin, dry mouth

• Blind as a bat: Blurred vision, dilated pupils

• Full as a flask: Urinary retention

What is the primary management for an anticholinergic overdose?

Supportive care, which includes stopping the drug, providing hydration, and managing symptoms (e.g., cooling for fever).

What is the specific antidote for a severe anticholinergic overdose, and why is it used cautiously?

Physostigmine. It is used cautiously because it is a cholinergic drug that can cause serious side effects like bradycardia and seizures.