drug therapy for treatment of MG, Alzheimer's, and urinary retention Flashcards
describe what happens when the parasympathetic nervous system is activated
- constricts pupils
- stimulates salivation
- slows heart
- constricts bronchioles
- stimulate digestion
- stimulates gallbladder
- contracts bladder
- stimulates sex organs
describe what happens when the sympathetic nervous system is activated
- dilates pupils
- inhibits salivation
- accelerates heart
- dilates bronchioles
- inhibits digestion
- stimulates release of glucose
- secretes epinephrine and norepinephrine
- relaxes bladder
- inhibits sex organs
true or false?
direct-acting cholinergic medications readily enter the central nervous system
false
rationale: direct acting cholinergic medications do not readily enter the central nervous system; thus, their effects occur primarily in the periphery
define myasthenia gravis
chronic autoimmune neuromuscular disease, weakness and rapid fatigue of muscles under voluntary control
describe the etiology of myasthenia gravis
defect in the transmission of nerve impulses to muscles
describe the pathophysiology of myasthenia gravis
occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction
describe the clinical manifestations of myasthenia gravis
- facial expression and swallowing, weakness of eye muscles
- diplopia (double/burred vision)
- dysphagia (difficulty swallowing)
- dysarthria (slurred speech)
- SOB
- -*hallmark sx: symptoms increase with exertion and improve with rest
describe drug therapy used to treat myasthenia gravis
- cholinergic drugs
- acetylcholinesterase inhibitor drugs
define neostigmine
used for long term treatment of myasthenia gravis and as an antidote for nondepolarizing skeletal muscle relaxants used in surgery
what is the use of neostigmine
diagnosis and treatment of myasthenia gravis. reverse the action of nondepolarizing neuromuscular agents
describe the pharmacokinetics of neostigmine
administered slowly intravenously, metabolized by liver, excreted in the kidneys
describe the action of neostigmine
- decreases the inactivation of acetylcholine in the synapses by the enzyme acetylcholinesterase
- by interfering with the breakdown of Ach, stimulates both nicotinic and muscarinic receptors which are involved in muscle contraction
describe the adverse effect of neostigmine
- cardiovascular and respiratory
- cardiac dysrhythmias, decreased cardiac output, hypotension, cardiac arrest, and respiratory depression which may indicate a cholinergic crisis
what are some contraindications of neostigmine
hypersensitivity, lung disease, heart disease, benign prostatic hypertrophy
what are some nursing implications regarding neostigmine
- preventing interactions: atropine/corticosteroids (will decrease effect)
- administerings the medication: with food/milk to decrease risk of gastric distress, ulceration
describe assessing for therapeutic effects with neostigmine
- increase in muscle strength
- decreased difficulty with chewing, swallowing, and speech
- absent ptosis
describe assessing for adverse effects with neostigmine
- increase in central nervous system effects such as convulsions, dizziness, drowsiness, secretions, broncho and laryngospasms, and respiratory failure
- pyridostigmine: indirectly increasing the concentration of acetylcholine at the NMJ and promoting increased cholinergic nicotinic receptor activation - has no unwanted CNS effect and does not cross blood brain barrier
describe pt teaching with neostigmine
- educate on wearing medical alert identification device
- rest between activities
- increase reporting and awareness to an increase in muscle weakness
- may have complaints of abdominal cramps, diarrhea, and difficulty breathing, these are all concerns
describe cholinergic crisis
- occurs from an overdose of acetylcholinesterase inhibitors
- this is an emergency, important to teach pts about the signs and symptoms
what are the signs and symptoms of cholinergic crisis
extreme weakness
- salivation
- lacrimation
- urinary incontinence
- diarrhea
- GI upset
- emesis
what is the treatment for cholinergic crisis
- atropine
- works on the muscarinic receptors (not nicotinic), so you will see changes in the heart, smooth muscles, and glands when this drug is administered to reverse or stop the cholinergic crisis
what are the characteristics of overstimulation of PNS
B: bronchoconstriction
A: apnea
G: gray vision
P: pupil constriction
U: urinary increase
D: diaphoresis
D: defecation
L: lacrimation
E: emesis
S: seizures
define alzheimer’s disease
memory loss and loss of other intellectual abilities serious enough to interfere with daily life
describe dementia
- broad/umbrella term
- Alzheimer’s falls under it
- group of thinking and social symptoms that interfere with daily functioning
describe the etiology of Alzheimer’s disease
most common form of dementia
describe the pathophysiology of Alzheimer’s disease
deficiency in cholinergic function in the cortex and basal forebrain
describe clinical manifestations of Alzheimers disease
most common early symptom is difficulty remembering newly learned information
what different drug therapies are used to treat Alzheimer’s disease
- cholinesterase inhibitors
- n-methyl-d-aspartate receptor antagonist
- cholinesterase inhibitor n-methyl-d-aspartate receptor antagonist
describe the principles of cholinergic treatment of Alzheimer’s disease
- goal of therapy is to slow memory and cognition loss
- cholinergics delay progression of disease if used in early stages - brings slight improvement in cognition and function
- other medications may be beneficial
which medication is the most commonly used acetylcholinesterase inhibitor
donepezil
define donepezil
- medication that is used to inhibit acetylcholinesterase
- permits accumulation of acetylcholine and increases stimulation of cholinergic receptors in the CNS/PNS
describe the pharmacokinetics of donepezil
absorption with oral administration in good and is unaffected with food, peak of action is 3-4 hours, metabolism is in liver, excretion is mainly in the urine
describe the action of donepezil
increases acetylcholine in the brain by inhibiting its metabolism
describe the use of donepezil
to treat mild, moderate, or severe Alzheimer’s disease , may also be used to enhance memory is neurological conditions such as MS
describe some adverse effects of donepezil
- CNS → fatigue, seizure-like activity, lightheadedness
- GI → increased nausea and vomiting
- respiratory → bronchoconstriction and difficulty breathing
- cardiovascular → decreased HR
what are some contraindications of donepezil
- hypersensitivity
- lung disease
- heart disease such as sick sinus syndrome (sinal node is pacemaker of the heart)
- bradycardia, irregular HR, and cardiac history of pauses
what are some nursing implications of donepezil
- preventing interactions
- administering the med
- assessing for therapeutic and adverse effects
- patient teaching
what are some other drugs in the same class as donepezil
galantamine hydrobromide
rivastigmine
define memantine
a n-methyl-d-aspartate (NMDA) receptor antagonist
describe the use of memantine
used for patients with moderate to severe Alzheimers disease
describe the pharmacokinetics of memantine
well absorbed orally, 100% absorption in GI tract, partially metabolized in the liver, excreted through the urine
what are some contraindications of memantine
hypersensitivity and renal failure
what are the adverse effects of memantine
- N+V
- dizziness
- diarrhea and constipation
- fatigue and body aches
what are some nursing implications of memantine
- preventing interactions
- administering med as directed
- assessing for therapeutic and adverse effects
- patient teaching (report any severe side effects)
other then atropine, what are some emergency treatments of cholinergic toxicity
- decontamination (hydrate to increase fluid volume and decrease concentration)
- activated charcoal (prevents digestion of meds in gut) and lavage
- pharmacologic treatment
give an overview of inhibitor n-methyl-d-aspartate receptor antagonist
- combination therapy for Alzheimer’s patients
- donepezil and meantine are a combination cholinesterase inhibitor and a NMDA
- used in patients with moderate to severe dementia
- assess for cardiovascular events, falls, GI upset, and overall mental status
describe the etiology and pathophysiology of urinary retention
- urinary retention may be due to sever factors:
- neurogenic bladder (spastic and flaccid)
- DM
- enlarged prostate
- pregnancy
- MS
- Parkinsons
- surgery
describe neurogenic bladder
any condition that impairs bladder and bladder afferent and efferent signaling from occurring - may be flaccid or spastic
describe spastic neurogenic bladder
- normal or small amount of urine, consistent involuntary contractions which results in wetting/leakage/incontinence issues
- can result from renal or spinal cord damage, or detrusor complications
describe flaccid neurogenic bladder
- large volume of fluid in bladder
- absence of contraction → can result from peripheral nerve damage or damage to spinal cord
describe the clinical manifestations of urinary rentention
- urinary retention or leakage
- may have sensation of a full bladder or incomplete bladder emptying
what type of drug therapy is used for urinary rentention
cholinergic agonist
describe the pharmacokinetics of bethanechol chloride
- well absorbed in GI tract
- site of metabolism and elimination is not known
- does not cross blood brain barrier, but does cross placenta
describe the action of bethanechol chloride
- parasympathomimetic agent
- acts at the cholinergic receptors in the urinary and GI tracts to increase muscle tone
describe the use of bethanechol chloride
nonobstructed urinary retention and neurogenic atony (loss of strength) of the bladder muscle
