• muscarinic – stimulate smooth mucles
• nicotinic – stimulate skeletal muscle

enzyme that degrades ACh = AChE 

• blocks ACh transmission which can diminish cognitive function, as in Alzheimer’s

direct acting

indirect acting muscle stimulants (anticholinesterases)

topical opthalamic cholinergics

bethanechol (Duvoid, Urencholine)

1.        ambenonium (Mytelase)

2.        edophonium (Tensilon)

3.        guanidine

4.        pyridostigmine

INDIRECT ACTING CHOLINERGICS MUCLE STIMULANTS (ANTICHOLINESTERASEs)

1.        carbachol, topical (Miostat)

2.        pilocarpine (Pilopine)

TOPICAL OPTHALAMIC CHOLINERGICS

For glaucoma

nope, affect whole body

except for the topical opthalamic preparations

1. mimic ACh to cause micturition in urinary retention

parasymp controls micturition (voiding) by contracting detrusor muscle and relaxing bladder sphincter – both voluntary and involuntary

1. inhibit release of AChE so that ACh remains in system longer

                                                               i.      MYASTHENIA GRAVIS = rapid fatigue (and lack of contraction) of skeletal muscles bc of low ACh from parasymp nerves

                                                              ii.      AChE inhibitor allows ACh to maintain skeletal muscle stamina

2. increased ACh allows MIOSIS (iris constriction)

                                                               i.      thereby opening blocked aqueous channels of eyes, reducing IOP for glaucoma

• rapid fatigue (and lack of contraction) of skeletal muscles bc of low ACh from parasymp nerves
• use anticholinesterases to prevent breakdown of ACh, which is low

1. topical usually few adv rxns (stay local to eyes), if any:
1. reduces acuity
2. headache
2. General full body (non opthalamic)
1. nausea, diarrhea, ab cramps, salivation
2. flushing
3. arrythmias
4. muscle weakness

1. asthma - bc of increased secretion
2. peptic ulcers - bc of increases gastric secretion
3. coronary artery disease 
4. hyperthyroidism
5. bethanechol (direct acting) contraindicated in those with mechanical GI or genitourinary obstruction
6. opthalamic cholinergic preparations contraindicated in secondary glaucoma, iritis, corneal abrasion, any acute inflammatory disease of eye
7. safety not established for pregnancy, lactation or children

1. hypertension
2. epilepsy
3. arrythmias
4. bradycardia
5. recent coronary occlusion
6. megacolon

1. palpate pelvis abdomen and scan bladder for retention
2. take BP and pulse

Urinary retention

Myasthenia Gravis

1. assess for muscle weakness like drooling, inability to swallow or chew, drooping eyelids, can’t perform repetitive movements like walking, combing hair, difficulty breathing and extreme fatigue

result of toxicity of cholinergics

1. Requires immediate attention/treatment; report immediately
2. Antidote given, like atropine IV
3. Symtoms are
1. severe ab cramping
2. diarrhea
3. excess salivation
4. muscle weakness
5. rigidity and spasm, jaw clenching

• watch for sxs of cholinergic crisis
• I/O
• Notify if doesn’t void after admin
• If fails to void, or incomplete, palpate bladder, use bladder scanner to determine residual

• monitor for sxs cholinergic crisis
• document presense or absence or increases in symptoms and adverse reactions before giving each dose
• for severe cases, can more frequently document
• document response or lack of response afterwards
• dosages are frequently changes according to effect early in therapy
• once controlled, symptoms fairly well managed with optimal dose

1. For subq admin, voiding usually 5-15 min
2. for oral, usually 30-90 min after
3. make sure pt has callight, urinal, etc

Admin of cholinergic for Myasthenia Gravis

dosing

how frequent of admin

issue of over and underdosing

1. at start, determinig dose difficult and dosages will change a lot
2. pts with severe symptoms need admin q 2-4 hours, even at night
3. are ER tabs for less freq doing, esp. for at night
4. NURSING ALERT – bc of dose change, very important to monitor symptoms and signs of drug overdosing or underdosing.  If noted, contact immediately, most likely need dose change.
1. Signs of overdosing are:

                                                               i.      muscle rigidity, spasm, salivations, jaw clenching

2. Signs of underdosing are:

                                                               i.      disease itself

                                                              ii.      very easily fatigued

                                                            iii.      srooping eyelids

                                                            iv.      difficuly breathing

1. Oral admin may produce excess salivation, ab cramps, flatus and diarrhea
2. will most likely subside once tolerance develops, few weeks
3. encourage ambulation to pass gas; may need rectal tube
4. record I/O if diarrhea
5. Inform PCP if excessive diarrhea bc can be sign of toxicity

In general

1. stress uninterrupted regimen

For Myasthenia Gravis

1. many pts adjust own doses according to daily needs
2. teach pts to understand signs of over and under dosing and steps to take if occurs; provide in written form
3. explain how to adjust dose up or down
4. pt should keep record of response and bring to appointments until symptoms well controlled and dose is stable
5. must wear or carry med ID indicating MG