53 terms

CNS Meds Pharm Test 2

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Opioid
A general term defined as any drug, natural or synthetic, that has actions similar to those of morphine
Strong Opioid agonists
Morphine
Other strong opioid agonists
(Fentanyl**, Meperidine, Methadone)
Moderate to strong opioid agonists
(Oxycodone, Codeine (cough suppressant), Hydrocodone, Tapentadol)
Morphine
Source - Seedpod of the poppy plant
Effect - Pain relief
Doesn't affect senses
Better on constant, dull pain (rather than sharp, intermittent Pain)
Administration routes: oral, IM, IV, subcutaneous, epidural, and intrathecal
Morphine Adverse Effects
Infants and elderly are especially sensitive. Tolerance to respiratory depression can develop
Increased depression with concurrent use of other drugs that have CNS depressant actions (eg, alcohol, barbiturates, benzodiazapines. Can compromise patients with impaired pulmonary function asthma, emphysema, kyphoscoliosis, chronic cor pulmonale, bariatric
Morphine Adverse Effects(cont'd)
Constipation
Orthostatic Hypotension
Urinary Retention
Cough Suppression
Biliary colic
Emesis
Elevation of ICP
Euphoria/dysphoria
Sedation
Miosis - pupil constriction
Neurotoxicity - delirium
Morphine Toxicity/Classic Triad & Tx
Toxicity
Clinical manifestations
Classic Triad
-Coma
-Respiratory depression
-Pinpoint pupils
Treatment -
Opioid Antagonist - Naloxone -
(half-life 2 hrs)
PCA
Device that delivers prescribed dose & allows pt to self-administer
Route: IV, transdermal, SQ, epidural
Benefits - Small frequent doses - steady level of drug, patient control, rapid relief, Minimizes risk of OD, Max dose within hour
Minimum interval (lock out or delay setting), Accelerated recovery
Risk - don't use correctly; family dosing patient
Pain Management in Pxs with Cancer
"an unpleasant sensory and emotional experience"(IASP)
Cause - Cancer and/or Treatment

Assess often; Ask what pain level is acceptable,
Believe the patient
Choose appropriate pain control measures
Deliver interventions timely, dose often and around the clock
Empower patient and family to control treatment
Adjuvant Analgesics
Used to complement the effects of opioids—not used as substitutes
NSAIDS
Antihistamines (vistaril)
Tricyclic antidepressants
Amitriptyline (Elavil)
Antiseizure drugs
Local anesthetics
Muscle relaxants
Corticosteroids
Non Opioid Analgesics
Nonsteroidal anti-inflammatory drugs
Acetaminophen
NSAIDS
NSAIDs (aspirin, ibuprofen, celecoxib)
Pain relief, reduce inflammation, reduce fever
Adverse - GI ulcer, acute renal failure, bleeding
Acetaminophen
Pain relief, reduce fever
No anti-inflammatory action
Adverse - Interacts with alcohol and warfarin
Potentially fatal liver damage
Asprin...
Pain relief, reduce fever
No anti-inflammatory action
Adverse - Interacts with alcohol and warfarin
Potentially fatal liver damage
The Blood-Brain Barrier (BBB)
Impedes entry of drugs into the brain
Passage across the BBB limited to lipid-soluble drugs
Mixed blessing of BBB
Adaptation of the CNS to Prolonged Drug Exposure
Different effects possible when drug is taken chronically versus initial use of drug

Increased therapeutic effects - weeks before full effect develops

Decreased intensity of side effects

Tolerance - decreased response

Physical dependence - withdrawal syndrome if abruptly discontinue meds
CNS Stimulants
Increase the activity of CNS neurons
Enhance the neuronal excitation; a few suppress the neuronal inhibition
In sufficient doses, all can cause convulsions
Limited clinical applications
Methylxanthines
Derivatives of xanthine
Caffeine
Few clinical applications
Widespread ingestion for nonmedical purposes
Dietary sources
Chocolate
Desserts
Soft drinks
Cola nut
Caffeine-Pharmacologic Effects
-Low doses - Decreases drowsiness and fatigue and increases capacity for prolonged intellectual exertion
-Increasing doses - Nervousness, insomnia, tremors Seizures with very large amounts
-Heart-increased rate, dysrhythmias
-Blood vessels-
Peripheral - vasodilation - Cerebral vessels - vasoconstriction (headache relief)
Bronchi-bronchodilation by smooth-muscle relaxation
Kidney -cause diuresis
Reproduction - birth defects (risk is low)
Anxiety Benzos
Anxiety - Clonazepam,
Lorazepam,
Diazepam,
Alprazolam (Xanax)
Insomnia - Sedative Hypnotics
Zolpidem (Ambien)
Zaleplon (Sonata)
Eszopiclone (Lunesta)
Ramelteon (Rozerem) - specific for insomnia (Affects/Stimulates Melanin production)
Benzodiazepines - Action and Indications
Action : enhance the effect of GABA (limits CNS)
>sedation, hypnotic(sleep inducing), reduce anxiety, anticonvulsant, muscle relaxant

Indications: anxiety, insomnia, agitation, seizures, muscle spasms, alcohol withdrawal, premedication for dental or medical procedures
Benzos RN Implications / Adverse Effects
Nursing implications
Dependence
Addiction
Tolerance

Adverse Effects:
CNS depression/amnesia
Sleep walking/driving
Respiratory depression
COPD
Risk to fetus
Present in breast milk
Anesthetics - Local / General
Local - Lidocaine (Xylocaine)
Procaine (Novocaine)
General - Intravenous
Propofol
Ketamine
Local Anesthetics - MOA
Mechanism of Action
Suppress pain by blocking sodium channels, thereby blocking impulse conduction along axons
Only in neurons located near the site of administration
Suppress pain without generalized depression of nervous system

Use with vasoconstrictors (Epinephrine)
Prolongs anesthesia
Reduces the risk for toxicity
Time Course of Local Anesthesia
Onset of local anesthesia
Perception is lost in this order:
1st - pain
2nd- cold
3rd - warmth
4th- touch
5th- deep pressure

AE - Adverse effects
Seizures,
CNS depression, Respiratory depression
Bradycardia to arrest
Allergic reaction
Lidocaine
Most widely used local anesthetic
Topical (Cream, Aerosol, Patch)
SQ injectable solution
Effects extended if given with epinephrine
Also used for cardiac dysrhythmias (IV form)
General Anesthetics
Goal:
- Unconsciousness & insensitivity to pain
Balance anesthesia
-Inhalation anesthetics eliminated by expired air
-Principal adverse effects Respiratory compromise & decreased cardiac performance
-Usually induced with short-acting barbiturate
-Opioids < required general anesthesia
Propofol
-Sedative hypnotic - short acting
-Indications: induction & maintenance anesthesia; mechanical ventilation; endoscopy; radiation therapy
-Route: IV
-Nursing implications:
Respiratory support immediately available
Caution with hypovolemic pts, esp. elderly
Reversal is quick
No analgesic action
Ketamine
-Dissociative anesthesia; sedation, immobility, analgesia, & amnesia
-Indications: minor surgery for children, change burn dressings,
-Route: IV
-Nursing implications:
Recovery - pt may have psychologic reactions
Avoid with hx of psychiatric illness
Parkinson's Disease (PD)
PD is a neurodegenerative disorder of the extrapyramidal system associated with disruption of neurotransmission in the striatum.

Affects over 1 million Americans
Second only to Alzheimer's disease as the most common degenerative disease of neurons
Symptoms generally appear in middle age and progress
No cure for motor symptoms
Drug therapy can maintain functional mobility for years (prolongs/improves quality of life)
Parkinson's Disease (PD) - Therapeutic Goals
Therapeutic goals
Ideal treatment (reverse neuronal degeneration or prevent further degeneration) does not exist
Goal is to improve patient's ability to carry out activities of daily life
Drug selection and dosages are determined by extent to which PD interferes with work, dressing, eating, bathing, etc.
Parkinson's Disease (PD) - Drug Therapy
Two major categories
-Dopaminergic agents
-By far the most commonly used drugs for PD
-Promote activation of dopamine receptors
-Levodopa and carbidopa (Sinemet)
Anticholinergic agents
-Prevent activation of cholinergic receptors Benztropine
Levodopa Uses PD
Highly effective, benefits increase over first few months
Most effective in first 2 years - by end of 5 years, symptoms may return to pretreatment level
Acute loss of effect (on-off phenomenon)
Gradual loss of effect
Orally administered, rapid absorption from small intestine
Food delays absorption
High-protein foods will reduce therapeutic effects
Levodopa Adverse Effects / Drug Interactions
Adverse effects
Nausea and vomiting
Dyskinesia (head bob, grimace, tic)
Cardiovascular effects
Psychosis
May darken sweat and urine
Can activate malignant melanoma
Drug interactions: first-generation antipsychotics, MAOIs, anticholinergics, pyridoxine
Food interactions: protein and vitamins with pyridoxine (B-6)
Carbidopa Uses/Advantages
Advantages
No adverse effects of its own
Increases the available levodopa in the CNS and allows for 75% decrease of levodopa dosage; therefore reduces cardiovascular adverse effects and N/V
Effects come mainly from levodopa when given in combination
Levodopa/carbidopa (Sinemet)
Switch from levodopa alone to combination
8-hour delay
Anticholinergic Agents For PD
Benztropine mesylate (Cogentin)
Mechanism of action: block acetylcholine; inhibit overactivity in brain
Primary use: younger patients with mild symptoms
Dose starts low and increases until desired effect is reached
Anticholinergic Agens - Adverse Effects and Client Teaching (PD)
Adverse effects: dry mouth, blurred vision, photophobia, urinary retention, constipation, tachycardia, glaucoma
Client Teaching:
-Relieve dry mouth with frequent drinks or sugarless hard candy
-Take with food or milk to prevent GI upset
-Avoid alcohol
-Wear dark glasses; avoid bright sunlight
-Do not stop taking abruptly
Amantadine (Symmetrel) PD
Adjunctive Therapy
Antiviral
MOA: inhibition Dopamine uptake, stimulate Dopamine release, block cholinergic & glutamate receptors
Onset: Rapid (2-3 days)
AE: confusion, lightheadedness, anxiety, blurred vision, urinary retention, dry mouth, constipation, skin discoloration

Dose & Administration:
PO: 100mg cap & syrup 10mg/ml
Contraindication: Renal Impairment
Drug Interactions: levodopa & anticholinergics- enhanced responsed
Dopamine Agonist Selegiline
Used alone or in combo with Levodopa
Use - retards progression of PD
Dose & Admin - PO, Transdermal patch
AE - insomnia (take before noon), orthostatic hypotension, GI symptoms
High dose - Hypertension

Drug Interactions - Levodopa - intensified adverse response
Meperidine - dangerous stupor, rigidity, agitation
Fluoxetine - combo has been fatal
Epilepsy
Definition - Group of disorders characterized by
excessive excitability of neurons in the CNS
- Can produce a variety of symptoms ranging from brief periods of unconsciousness to violent convulsions

Initiated by synchronous, high-frequency discharge from a group of hyperexcitable neurons called a focus
Focus may result from
Congenital defects
Hypoxia at birth
Head trauma
Stroke
Cancer
Epilepsy: Therapeutic Considerations
Monitoring plasma drug levels (not all AED's need this)
Promoting patient adherence
-Education; no driving during monitor period (6 months in Okla)
Withdraw antiepileptic drugs slowly
Suicide risk - antiepileptic drugs
Seizure frequency chart - evaluate treatment effectiveness
Phenytoin (Dilantin) - Epilepsy
Most widely used AED
Active against Partial and tonic-clonic seizures
Action: selective inhibition of sodium channels
Suppresses activity of seizure generating neurons
Dose & Admin - PO; IV
Therapeutic Blood Level - 10-20mcg/mL
Phenytoin (Dilantin) AE
Adverse effects
Nystagmus
Sedation
Gingival hyperplasia
Skin rash
Effects in pregnancy-teratogen
Cardiovascular effects:
dysrhythmias
hypotension
Phenytoin (Dilantin) - Drug Interactions
Drug interactions
-Decreases the effects of oral contraceptives, warfarin, and glucocorticoids
-Dilantin levels:
↓ w/ chronic alcohol
-When discontinuing treatment, dose should be reduced gradually
-Abrupt withdrawal may precipitate seizure
Carbamazepine (Tegretol) - Uses and MOA
Uses
-Epilepsy
-Bipolar disorder
-Trigeminal and glossopharyngeal neuralgias

Mechanism of Action
-selective inhibition of sodium channels
-Suppresses activity of seizure generating neurons
Carbamazepine (Tegretol) - AE
Adverse effects
-Neurologic effects: nystagmus, ataxia
-Hematologic effects: leukopenia, anemia, thrombocytopenia
-Birth defects - Teratogenic
-Hypo-osmolarity
-Dermatologic effects: rash, photosensitivity reactions
Diazepam (Valium) - Benzo/Uses
-Use: MANAGEMENT OF GENERALIZED CONVULSIVE STATUS EPILEPTICUS (SE) - seizures lasting 20-30 minutes
-Terminates seizures quickly
-Action - short duration (2hr)
-Must begin long term anticonvulsant med therapy very soon
Myasthenia Gravis
Pathophysiology
-Characterized by fluctuating muscle weakness and predisposition to rapid fatigue
-Common symptoms
--Ptosis, dysphagia, weakness of skeletal muscles
-Autoimmune process in which antibodies attack nicotinicM receptors on skeletal muscle
Cholinesterase inhibitors are?
...drugs that prevent the breakdown of acetylcholine (ACh) by acetylcholinesterase (ChE) By preventing the inactivation of ACh, the cholinesterase inhibitors improve the actions of ACh released from cholinergic neurons. Since cholinesterase inhibitors can intensify transmission at all cholinergic junctions (muscarinic, ganglionic, and neuromuscular), these drugs can elicit a broad spectrum of responses. Because they lack selectivity, cholinesterase inhibitors have limited therapeutic applications. Cholinesterase inhibitors are also known as anticholinesterase agents.
Cholinesterase Inhibitors (two Drugs that are Cholinesterase Inhibitors)

Indications:
Action:
Therapeutic Effects:
Pyridostigmine (Mestinon)
Neostigmine (Prostigmin)

-Indications: treat muscle weakness in patients with MG
-Action: inhibits breakdown of Ach & prolongs its effect
-Therapeutic Effects: ↑muscular functions and strength
Pyridostigmine (Mestinon)
Neostigmine (Prostigmin)

Effets...
Effects:
Muscarinic - bradycardia, bronch constrict, urgency, increased GI motility
Muscles - increased force of contraction
CNS - mild stimulation
Pyridostigmine (Mestinon)
Neostigmine (Prostigmin)

Adverse Effects...
Adverse Effects: excess muscarinic effect; paralysis of respiratory muscles, seizure, bradycardia, GI upset