Block 5 Drugs Flashcards
1
Q
NMJ Drugs (13)
A
Pyridostigmine
Prednisone
Tubocurarine
Atracurium
Rocuronium
Succinylcholine
Diazepam
Baclofen
Gabapentin
Dantrolene
Botulinum toxin
Tizanidine
Azathioprine
2
Q
Pyridostigmine
A
NMJ Drugs
Classification: carbamate type cholinesterase inhibitor
- *Main clinical applications:**
- treatment of myasthenia gravis (to increase skeletal muscle tone)
- to reverse the actions of nondepolarizing neuromuscular blockers after surgery
- effects last 3-6 hours
- *Pharmacodynamics: Mechanisms/Sites of Action**
- competes with acetylcholine for its binding site on acetylcholinesterase. By interfering with acetylcholine metabolism, pyridostigmine potentiates the action of acetylcholine at both the skeletal muscle (nicotinic receptor) and muscarinic receptors
- *Adverse Effects:**
- increased muscarinic effects: increased gastric motility and GI tone; bradycardia, stimulation of the sweat and salivary glands; bronchoconstriction
3
Q
Prednisone
A
NMJ Drugs
Classification: corticosteroid
- *Main clinical applications: **
- used in many conditions; effective as an immunosuppressant and anti-inflammatory agent
- *Pharmacodynamics: Mechanisms/Sites of action:**
- prevents or suppresses inflammation and immune responses when administered at pharmacological doses; induces a response by modifying transcription and, ultimately, protein synthesis that results in inhibition of leukocyte infiltration at the site of inflammation, interference in the function of mediators of inflammatory response, and suppression of humoral immune responses
- prednisone is a prodrug; it is metabolized in the liver to its active form, prednisolone
- *Adverse Effects:**
- resulting from withdrawal: fever, myalgia, malaise
- continued use of large doses can lead to ulcer formation, hyperglycemic actions, osteoporosis, glaucoma, behavioral disturbances, iatrogenic adrenal insufficiency
4
Q
Tubocurarine
A
NMJ Drugs
Classification: nondepolarizing, neuromuscular blocking agent
Main clinical applications: skeletal muscle relaxant
- *Pharmacodynamics: Mechanisms/Sites of action:**
- competes with acetylcholine for cholinergic receptor sites at the neuromusclar junction, resulting in skeletal muscle paralysis
- *Adverse Effects:**
- has the highest potential amoung neuromuscular blocking agents to produce histamine release and vasodilation that can result in hypotension; ganglia blockade can result in reduced GI tract tone and motility
5
Q
Atracurium
A
NMJ Drugs
Classification: intermediate-acting, nondepolarizing, neuromuscular blocking agent
- *Main clinical applications:**
- as an adjunct to general anesthesia during surgery or mechanical ventilation to provide skeletal muscle relaxation
- also used as an aid to tracheal intubation
- *Pharmacodynamics: Mechanisms/Sites of action:**
- competes with acetylcholine for cholinergic receptor sites at the neuromuscular junction, resulting in skeletal muscle paralysis
- *Adverse Effects:**
- may be due to histamine release that can cause flushing, edema, urticaria, pruritus, bronchospasm, and/or wheezing but produces less than tubocurarine
6
Q
Rocuronium
A
NMJ Drugs
Classification: short-acting, nondepolarizing, neuromuscular blocking agent
- *Main clinical applications:**
- an adjunct to general anesthesia during surgery or mechanical ventilation to provide skeletal muscle relaxation
- onset of action comparable to that of succinylcholine, but its duration of action is significantly longer. Due to its rapid onset, rocuronium may be a useful alternative to succinylcholine for rapid sequence induction in certain situations
- also used as an aid to tracheal intubation
- *Pharmacodynamics: Mechanisms/Sites of action**
- competes with acetylcholine for cholinergic receptor sites at the neuromuscular junction, resulting in skeletal muscle paralysis
- *Adverse Effects:**
- adverse events occurring at a rate of >1% have not been reported (produces little histamine release and no ganglion blockade, so hypotension and bronchospasm are not associated with its use)
7
Q
Succinylcholine
A
NMJ Drugs
Classification: depolarizing-type, skeletal muscle relaxant
Main clinical applications: for intravenous administration to produce rapid neuromuscular blockade (allows endotracheal intubation within 60 seconds)
- *Pharmacodynamics: Mechanisms/Sites of actioin:**
- ultra short-acting, depolarizing skeletal muscle relaxant. it competes with acetylcholine for the cholinergic receptors of the motor endplate and produces a prolonged depolarization that results in initial fasciculation of the skeletal muscles followed by muscle paralysis; rapidly hydrolyzed by plasma pseudocholinesterase (t1/2 ~1min)
- *Adverse Effects:**
- hyperkalemia has been reported in burn patients, and in patients with severe abdominal infections, tetanus, massive trauma, stroke, spinal cord injury, and neuromuscular disease
- pseudocholinesterase genetic variants do not efficiently metabolize succinylcholine, thus prolonging its duration of action
8
Q
Diazepam
A
NMJ Drugs
Classification: benzodiazepine
- *Main clinical applications:**
- multiple: anesthetic, skeletal muscle relaxant, anticonvulsant, anxiolytic/sedative/hypnotic
- *Pharmacodynamics: Mechanisms/Sites of action**
- binds to an allosteric site on the GABA-A receptor-chloride channel complex, resulting in GABA-mediated increases in chloride conductance, hyperpolarization, and neuronal inhibition
- *Adverse Effects:**
- generates active metabolites so long duration of drug action
- most of the adverse effects associated with diazepam therapy are dose-dependent; CNS-related effects include headache, drowsiness, ataxia, dizziness, confusion, depression, syncope, fatigue, tremor, and vertigo. Tolerance may develop to these effects.
9
Q
Baclofen
A
NMJ Drugs
Classification: skeletal muscle relaxant; spasmolytic drug
- *Main clinical applications:**
- used to treat spasticity and improve mobility in patients with multiple sclerosis and other spinal cord lesions
- *Pharmacodynamics: Mechanisms/Sites of action:**
- activates GABA-B receptors in spinal cord which results in hyperpolarization by increasing K+ conductance
- *Adverse Effects:**
- most common adverse effect of oral or intrathecal baclofen is drowsiness (63%); nausea/vomiting (4-12%), constipation (2-6%); muscular weakness and hypotonia are dose-related effects of baclofen
- abrupt discontinuation of baclofen may result in a withdrawal syndrome associated with increased spasticity, hallucinations, and seizures; baclofen therapy should be withdrawn slowly
10
Q
Gabapentin
A
NMJ Drug, Antiepileptic Drugs
Classification: oral anticonvulsant; neuropathic pain medication; spasmolytic drug
- *Main clinical applications:**
- control of seizures associated with epilepsy
- reduces pain and improves some quality-of-life measures in patients with a wide range of neuropathic pain syndromes, e.g. painful diabetic neuropathy, postherpetic neuralgia (PHN) - the burning, stabbing pain or aches that may last for months or years after an attack of shingles
- useful in the management of spasticity
- *Pharmacodynamics: Mechanisms/Sites of action:**
- efficacy not related to modulation of GABA system; does inhibit some classes of Ca2+ channels
- possesses high lipid solubility, is not metabolized by the liver, has no protein binding, and is devoid of the usual drug interactions (e.g. enzyme induction); and is excreted in the urine
- *Adverse Effects:**
- fatigue, drowsiness
11
Q
Dantrolene
A
NMJ Drugs
Classification: spasmolytic drug; skeletal muscle relaxant
- *Main clinical applications:**
- drug of choice for treating malignant hyperthermia
- muscle response to direct stimulation is attenuated; produces generalized, mild weakness of skeletal muscles and overall improvement in muscle tone
- *Pharmacodynamics: Mechansims/Sites of action:**
- peripherally acting skeletal muscle relaxant that reduces skeletal muscle contraction by inhibiting calcium release from the sarcoplasmic reticulum; this “uncouples” the excitation-contraction process, making dantrolene useful in treating malignant hyperthermia
- *Adverse Effects:**
- has little or no effect on cardiac or smooth muscle at doses used for skeletal muscle relaxation
- common adverse effect of dantrolene therapy is muscle weakness
12
Q
Botulinum toxin
A
NMJ Drugs
Classification: skeletal muscle relaxant
- *Main clinical applications:**
- for treatment of cervical dystonia in adults, and blepharospasm (abnormal contraction or twitch of eyelid) and strabismus (eyes not properly aligned with each other) associated with dystonia in adolescents and adults
- for focal spasticity
- *Pharamcodynamics: Mechanisms/Sites of action:**
- selective for ACh terminals
- irreversibly inhibits the release of acetylcholine (cleaves a protein (SNAP-25) integral to the successful docking and release of acetylcholine from vesicles situated within nerve endings)
- *Adverse Effects:**
- depends on the indication and site of injection, e.g. for blepharospasm, the most frequently reported adverse reactions included ptosis (20%), superificial punctuate keratitis (inflammation of cornea (6%), and xerophthalmia (dry eyes) (6%)
- injection site pain; can also include dysphagia and dyspnea
13
Q
Tizanidine
A
NMJ Drugs
Classification: CNS spasmolytic, muscle relaxant
Main clinical applications:
For the acute and intermittent management of increased muscle tone associated with spasticity
- *Pharmacodynamics: Mechanism/Sites of action:**
- centrally acting alpha-2 adrenergic agonist
- for treatment of spasms, and muscle tightness caused by multiple sclerosis, back pain and spinal injuries
- *Adverse Effects:**
- weakness, sedation, xerostomia, dose-related hypotension in patients treated with single oral doses
14
Q
Azathioprine
A
NMJ Drugs
Classificaton: immunosuppressive
Main clinical applications: Immunosupressant for multiple conditions including myasthenia gravis, rheumatoid arthritis, systemic lupus erythematosus
Pharmacodynamics: Mechanisms/Sites of action:
Azathioprine is metabolized to 6-mercaptopurine; inhibits DNA and RNA synthesis, resulting in inhibition of cell proliferation, especially leukocytes
Adverse Effects:
Nausea/vomiting; leukopenia and thrombocytopenia are dose-dependent
15
Q
Parkinson Drugs (10)
A
L-DOPA + carbidopa (Sinemet)
Ropinirole
Pramipexole
Apomorphine
Amantadine
Benztropine
Trihexyphenidyl
Selegiline
Rasagiline
Entacapone
16
Q
L-DOPA + carbidopa
(Sinemet)
A
Parkinson Drugs
Classification: antiparkinsonian agent: dopamine precursor + peripheral decarboxylase inhibitor
Main clinical applications: for treatment of Parkinson’s disease
- *Pharmacodynamics: Mechansims/Sites of action**
- L-DOPA is the metabolic precursor of dopamine
- carbidopa is added to L-dopa to inhibit the peripheral metabolism of L-DOPA; thus, more L-DOPA is available for transport to the brain
- *Adverse Effects:**
- dyskinesia, choreiform reaction and dystonic reaction occur in up to 80% of patients receiving L-DOPA therapy for >3 years
- orthostatic hypotension
17
Q
Ropinirole
A
Parkinson Drugs
Classification: antiparkinsonian agent: non-ergot alkaloid dopamine D2/D3 agonist
- *Main clinical applications: **
- for treatment of Parkinson’s disease, both as early monotherapy and in combination with L-dopa in advanced disease
- treatment for restless legs syndrome (mechanism unknown)
- *Pharmacodynamics: Mechanisms/Sites of action**
- non-ergot alkaloid dopamine agonist at both dopamine D2-receptors and D3-receptors (binding affinity for D3>D2). Although affinity of ropinirole is higher at D3-receptors than at D2-receptors, the relevance of binding at D3-receptors in Parkinson’s disease is unknown; motor improvement effects attributed to D2 actions
- *Adverse Effects:**
- nausea/vomiting, dizziness, postural hypotension, lower extremity edema, hallucinations
18
Q
Pramipexole
A
Parkinson Drugs
Classification: antiparkinsonian agent: non-ergot alkaloid dopamine D2/D3 agonist
- *Main clinical applications:**
- for treatment of Parkinson’s disease, both as early monotherapy and in combination with L-dopa in advanced disease
- *Pharmacodynamics: Mechanisms/Sites of action**
- non-ergot alkaloid dopamine agonist at both dopamine D2-receptors and D3-receptors (binding affinity for D3>D2). Although affinity of ropinirole is higher at D3-receptors than at D2-receptors, the relevance of binding at D3-receptors in Parkinson’s disease is unknown; motor improvement effects attributed to D2 actions
- *Adverse Effects:**
- nausea/vomiting, dizziness, postural hypotension, lower extremity edema, hallucinations
