Pharm chapter 21 cholinergic blocking drugs

What are cholinergic blocking drugs?

Drugs that block or inhibit the actions of acetylcholine (ACh) in the parasympathetic nervous system (PNS)

Cholinergic blocking drugs are also known as:

anticholinergics, parasympatholytics, and antimuscarinic drugs

Cholinergic blocking drugs mechanism of action:

Compete with ACh for binding at muscarinic receptors in the PNS

As a result, ACh is unable to bind to the
receptor site and cause a cholinergic effect.

Cholinergic blocking drugs effects:

Decrease intestinal and gastric secretions

Decrease motility and peristalsis

Urinary retention

Decreased bronchial secretions, salivation, and sweating

Decreased bronchial secretions

Dilated bronchial airways

Central nervous system indications for cholinergic blockers

Decreasing muscle rigidity and muscle tremors

Parkinson’s disease

Drug-induced extrapyramidal reactions such as those associated with antipsychotic drugs 

Cardiovascular system indications for cholinergic blockers

High doses result in increased heart rate

Atropine is used primarily for cardiovascular disorders

Atropine increases HR with bradycardia

Respiratory system indications for cholinergic blockers

Blocking the cholinergic stimulation of the PSNS allows unopposed action of the SNS.

Results

Decreased secretions from the nose, mouth, pharynx, and bronchi- Atropine

Relaxed smooth muscles in the bronchi
and bronchioles- Ipratropium (Atrovent)

Decreased airway resistance

Bronchodilation

Cholinergic blockers are used to treat what respiratory conditions?

Exercise-induced bronchospasms

Chronic bronchitis

Asthma

Chronic obstructive pulmonary disease

Gastrointestinal system indications for cholinergic blockers

Blockade of PNS results in:

Decreased secretions

Relaxation of smooth muscle

Decreased GI motility and peristalsis

Irritable bowel disease

GI hypersecretory states

The PNS controls gastric secretions and smooth muscles that produce gastric motility

Genitourinary system indications for cholinergic blockers

Oxybutynin (Ditropan),

˜Overactive bladder

˜Antispasmodic for neurogenic bladder associated with spinal cord injuries and congenital conditions as spina bifida

Tolterodine (Detrol)

˜Urinary frequency

Urge Incontinence 

What is neurogenic bladder?

complete disruption of both motor and sensory nervous system control over the bladder. No ability for initiate voiding, no sensation of bladder fullness

Contraindications for cholinergic blockers

˜Known drug allergy

˜Angle-closure glaucoma

˜Acute asthma or other respiratory distress

˜Myasthenia gravis

˜Acute cardiovascular instability

˜GI or GU tract obstruction (e.g., benign prostatic hyperplasia [BPH])

Toxicity and OD of cholinergic blockers

Symptomatic and supportive therapy

Physostigmine for atropine OD

The nurses should asses for what before giving cholinergic blockers?

Assess for allergies, presence of BPH, urinary retention, glaucoma, tachycardia, myocardial infarction, heart failure, hiatal hernia, and GI or GU obstruction.

Cholinergic blocking drugs may cause a dry mouth, this can be handled by:

Chewing gum, frequent mouth care, and hard candy

What is the antidote for atropine?

Physostigmine

Anticholinergics taken by older adults may lead to higher risk for…

heatstroke because of the effects on heat-regulating mechanisms.

Patients should be taught what when taking anticholinergics to avoid overheating?

to limit physical exertion and avoid high temperatures and strenuous exercise.