Pharmacology Study Guide: Anticonvulsants PDF

Module 3 Pharmacology The Concept of cognition is defined as “the process of thought that embodies perception, attention, visuospatial cognition, language, learning, memory, and executive function with the higher-order thinking skills of comprehension, insight, problem-solving, reasoning, decision...

Module 3 Pharmacology The Concept of cognition is defined as “the process of thought that embodies perception, attention, visuospatial cognition, language, learning, memory, and executive function with the higher-order thinking skills of comprehension, insight, problem-solving, reasoning, decision making, creativity, and metacognition The nervous system can be divided into two major regions: the central and peripheral nervous systems. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else. Common CNS disorders Include: Anxiety Depression Schizophrenia ADHD Seizures Parkinson’s Anticonvulsants Mechanism of Action Stabalize cell membranes and supress the abnormal electric impulses in the cerebal cortex CNS depressant Indications of use Treatment and preventions of seizures but do not provide a cure Treatment of other conditions such as neuropathic pain (example- Gabapentin) Common medications Phenytoin (brand name Dilantin) Levetiracetam (brand name Keppra) Gabapentin (brand name Neurontin) Valproic acid (valproate, divalproex) Pharmacological effects Increase the threshold of activity in the motor cortex, making it difficult for a nerve to become excited Limit the spread of a seizure discharge from its origin by repressing the transmission of impulses from one nerve to the next Reduces the speed of the nerve impulse conduction within a neuron Adverse/Side Effects Behavioural and mood changes (suicidal ideation, irritability, aggressive behaviour) Fatigue Dizziness Somnolence (drowsiness) Ataxia ( poor muscle control that causes clumsy movements) GI upset/discomfort Blurred vision Anticonvulsants Nursing considerations Taper dose- do not abruptly stop medications Monitor for worsening depression, suicidal thoughts, or behaviour, and/or any unusual changes in mood or behaviour Client Health Teaching Take medications as directed Can take weeks for therapeutic effect Do not abruptly stop taking medications Avoid alcohol and other CNS depressants May cause increased drowsiness and dizziness Monitor for suicidality Phenytoin Mechanism of action: Improves evidence of seizures, interferes with sodium channels in the brain- decreases high-frequency neuronal discharges Indications of use: treatment of tonic-clonic (grand mal) and psychomotor (temporal lobe) seziures. Prevention and treatment of seizures occurring during or following neurosurgery Adverse/Side effects: nystagmus (involuntary rhythmic eye movements), ataxia, slurred speech, decreased coordination, somnolence and mental confusion. SAFETY: SERIOUS/FATAL EFFECTS: dermatologic reactions, toxic epidermal necrolysis (TEN), stevens-johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), hematopoietic complications, acute hepatoxicity Administration considerations: must administer slowly, IV: cardiac monitoring and in-line filter, caution in clients with renal or hepatic impairment, elderly clients may require dosage adjustment Nursing considerations: contraindicated in pregnancy, IV administration: cardiac monitoring required, serum drug monitoring required, taper dose, many potential drug interactions with phenytoin, discontinue at first sight of rash Phenytoin Client health teaching: take medications as directed, can take weeks for thearapeutic effect, abrupt discontinuation can cause status epilepticus, avoid alcohol and other CNS depressants, diabetic clients- monitor BGs carefully Contradictions: pregnancy, heart block, several drug interactions Levetiracetam Mechanism of action: the exact mechanism of action is unknown, this medication may interfere with sodium, calcium, potassium or GABA transmission Indications of use: used for partial-onset seizures in clients with epilepsy Adverse/Side effects: behavioural/mood changes, somnolence, fatigue, irritability, coordination difficulties SAFETY: SERIOUS/FATAL EFFECTS: anaphylaxis or angioedema, dermatologic reactions, TEN, SJS, hematopoietic complications Nursing considerations: plasma levels can gradually decrease during pregnancy and should be monitored closely, safety and effectiveness in pediatric clients 12 years of age and older has been established, levetiracetam immediate release and solution can be used in clients as young as 1 month old, levetiracetam should not be stopped abruptly or withdrawal seizures may occur, use with caution in clients with renal impairment. Monitor for safety mobility and falls risk Contradictions: clients who are suicidal, clients with altered hematology Client health teaching: take medications as directed, may cause increased dizziness and somnolence. Clients/family/caregivers should also monitor carefully for suicidality during medication therapy Gabapentin Mechanism of action: the exact mechanism of action is unknown; this medication is structurally similar to GABA. But does not act on GAPA receptors or influence GABA. Indications of use: used for partial seizures and neuropathic pain Adverse/Side effects: risk of suicidal thoughts or behaviour, depression, mood changes, dizziness, CNS depression, DRESS, multiorgan hypersensitivity Gabapentin SAFETY: consider falls precautions for elderly. Monitor closely for suicidal ideation and DRESS syndrome Administration: first dose at bedtime to decrease dizziness and drowsiness, caution in use with children and elderly Nursing considerations: do not take within 2 hours of antacid medications, taper dose; do not stop abruptly. Monitor for worsening depression. Suicidal thoughts or behaviour/mood changes. Contradictions: pregnancy Client health teaching: take medications as directed, do not take within 2 hours of antacid medications, can increase drowsiness and dizziness, monitor for suicidality. Antiparkinson Medications Mechanism of Action Increasing levels of dopamine and/or antagonizing the effects of acetylcholine Indications of use Slows progression of disease; does not cure Common medications Carbidopa/levodopa (brand name Sinemet) Selegiline (brand names eldepryl, emsam and selgin) Amatadine (brand name gocovri) Pharmacological effects Increases or replaces the levels of dopamine in the brain, thus improving the symptoms of parkinson’s disease Antiparkinson Medications Adverse/Side Effects GI upset insomnia Dizziness Somnolence (drowsiness) Hallucinations, delirium, psychosis Nursing considerations Monitor for worsening depression, suicidal thoughts, or behaviour, and/or any unusual changes in mood or behaviour Patients should be instructed to plan their mealtimes around medication times to improve the ability to use utensils Patient education- avoiding diets high in protein due to decreased absorption of the medication Client Health Teaching Take medications as directed Avoid taking OTC cold medicine while using antiparkinson medications Avoid alcohol and other CNS depressants May cause increased drowsiness and dizziness or insomnia Monitor for suicidality Avoid high protein diets Can cause hallucinations Carbidopa/Levodopa Mechanism of action: levodopa- the metabolic precursor of dopamine, crosses the blood-brain barrier then is converted to dopamine in the brain. Carbidopa- helps stop the breakdown of levodopa, reduces the levodopa- induced nausea and vomiting. Indications of use: for parkinsons disease, for progressive supranuclear palsy (PSP), treats restless leg syndrome Adverse/Side Effects: depression, suicidal ideation, hallucinations, fatigue, neuroleptic malignant syndrome (NMS) symptoms, dyskinesia (involuntary body movements), constipation, discolored body fluids, hypermobility with long-term use, higher risk for melanoma SAFETY: observe carefully for depression and suicidal ideation Administration: avoid high-protein diets, monitor hepatic, renal and hematopoietic functions, if gastic irritation then eat food shortly after Nursing considerations: use in clients >18 years, can take several weeks to see therapeutic effects, contraindicated for use with monomine oxidase inhibitors (MAOIs), caution whilst driving or operating heavy machinery during treatment, monitor dosage reduction or discontinuation -NMS, plan meal times around medication times Client health teaching: take medications at regular intervals as directed, medications may cause increased drowsiness, dizziness and orthostatic changes, instruct clients to assess skin to monitor for new lesions ***Parkinson’s disease is linked to an increase in a protein known as alpha- synuclein that is toxic to the cells of the substantia nigra nucleus in the midbrain*** Selegiline Mechanism of action: inhibits MAO-B, blocking the breakdown of dopamine Indications of use: adjunct in the management of parkinsonian clients being treated with levodopa/carbidopa who exhibit deterioration in the quality of their response to this therapy Adverse/Side Effects: side effects are dose-dependent, with larger doses posing a hypertensive crisis risk in conjunction with the consumption of food or beverages with tyramine. Administration: avoid foods with tyramine (foods that are aged, fermented or cured like aged cheeses, cured meats, smoked fish, kimchi) Nursing considerations: large doses of selegiline may inhibit MAO-A that promotes metabolism of tyramine in the GI tract, which can cause a hypertensive crisis Client health teaching: avoid foods high in tyramine, may increase drowsiness, dizziness, hallucinations, sexual urges, gambling (abnormal behaviours) Contradictions: tyramine Amantadine Mechanism of action: the exact mechanism of action is unknown, amantadine is an antiviral drug that acts on dopamine receptors Indications of use: for parkinsons disease, medication-induced extrapyramidal symptoms, influenza A Amantadine Adverse/Side Effects: congestive heart failure, suicidal ideation, peripheral edema can occur, can cause intense gambling urges, sexual urges, intense urges to spend money, inability to control these urges, increased risk of melanoma, anticholinergic side effects Contradictions: known hypersensitivity Administration: monitor renal function, monitor mental state, assess blood pressure Nursing considerations: use cautiously with renal impairment. This drug may cause suicidal ideation, do not stop abruptly, NMS has been associated with dose reduction or withdrawal of amantadine therapy Client health teaching: take medication as directed, may cause drowsiness, dizziness, orthostatic blood pressure changes, avoid using with OTC cold medications or alcohol CNS depressants- barbiturates Mechanism of action Produce sedation and drowsiness by altering cerebellar function and depressing the actions of the brain and sensory cortex Indications for use Primarily used as an anti-convulsant Also used as a sedative May also be used as a pre-anesthetic agent CNS depressants- barbiturates Nursing considerations Do not use for children less than 1 month of age May harm fetus during pregnancy Avoid use in geriatric clients Adverse/side effects CNS depression Suicidal thoughts or behaviours GI disturbances Rashes Some blood disorders that can be fatal Habit forming Contradictions Clients with severe renal and hepatic disorders Clients with Severe respiratory depression Clients with dyspnea or airway obstruction Clients with porphyria Client teaching Take medication as prescribed Do not abruptly stop taking medication, can cause seizure activity Do not take with alcohol or other CNS depressants Female clients using oral contraceptives should use non hormonal contraceptives during therapy involving barbiturate use Overdosage Onset of symptoms following a toxic oral exposure to barbiturates may not occur until several hours following ingestion Phenobarbital Mechanism of action: alters cerebellar function and depresses actions of the brain and sensory cortex Indications of use: when sedation is needed, seizures Adverse/Side Effects: CNS depression; overdosage and cause death. May cause suicidal thoughts or behaviour, respiratory depression, GI upset Contradictions: severe renal and hepatic disorders, severe respiratory depression, dyspnea, or airway obstruction; porphyria. Not for children under 1 month of age, not for use in pregnancy, avoid in geriatric clients Administration: orally, IM or IV. Taper dose, do not stop abruptly Nursing considerations: take as directed, may be habit forming, do not take with other CNS depressants or alcohol Client health teaching: take only as prescribed, do not abruptly stop, do not take with alcohol or other CNS medications, may be habit forming CNS depressants- benzodiazepines Mechanism of action Binds to specific GABA receptors to potentiate the effects of GABA Indications for use Used for sedation Anti-anxiety Anticonvulsant CNS depressants- benzodiazepines Nursing considerations May cause hallucinations, tremors, agitation May harm fetus during pregnancy Children and elderly are more likely to experience paradoxical reactions Initial dosage should not exceed 2mg. Elderly or debilitated clients may be more susceptible to the sedative and respiratory depressive effects Adverse/side effects Profound sedation Respiratory depression Coma Death Sedation/drowsiness Habit forming Contradictions Clients with severe renal and hepatic disorders Clients with Severe respiratory depression Clients with dyspnea or airway obstruction Clients with porphyria Client teaching Take medication as prescribed Caution whilst driving or operating machinery Falls risk Do not consume alcohol for 24-48 hours after receiving lorazepam Lorazepam Mechanism of action: binds to specific GABA receptors to potentiate the effects of GABA Indications of use: reduce anxiety, reduce seizure activity, preanesthetic Adverse/Side Effects: oversedation and drowsiness, potentially fatal (respiratory depression), overdosage can cause coma and death. Falls risk, Contradictions: severe hepatic impairment, respiratory depression, acute narrow angle glaucoma, pregnancy and lactation, not for children under 12 Administration: SL, PO, IV, use cautiously in elderly, consider smaller doses for liver dysfunction Nursing considerations: flumazenil used for overdose, monitor for falls risk, take medication as prescribed, do not abruptly stop If in long-term therapy, avoid alcohol, avoid operating machinery or driving Client health teaching: take only as prescribed, do not abruptly stop, do not take with alcohol, may be habit forming, falls risk Anti-depressants 4 classes of anti-depressant: 1. Tricyclic antidepressants (TCAs) 2. Selective serotonin reuptake inhibitors (SSRIs) 3. Serotonin-norepinephrine reuptake inhibitors (SNRIs) 4. Monoamine oxidase inhibitors (MAOIs) Anti-depressants (TCAs) Mechanism of action TCAs tend to have sedative and anticholinergic effects. They act by inhibiting presynaptic reuptake of NE and 5-HT into nerves. The choice of TCA depends on individual response and tolerance to the drug. Indications for use Used to treat depression Used to treat chronic neuropathic pain Used to treat insomnia Nursing considerations Often administered at bedtime due to sedating effects and are contraindicated with MAOIs Geriatric clients are particularly sensitive to the anticholinergic side effects Elderly patients at higher risk for falls Should not be used in children Should not be used in those pregnant or lactating Adverse/side effects Constipation, urinary retention cardiac disturbances hypotension drowsiness sexual dysfunction Anti-depressants (TCAs) Contradictions myocardial infarction concurrent use of MAOIs pregnancy, lactation history of seizures hepatorenal diseases pre-existing cardiovascular disorders angle-closure glaucoma, urinary retention, Prostate hypertrophy, GI or GU surgery Client teaching Take medication as prescribed Risk of suicidality Falls risk Anti-depressants (SSRIs) Mechanism of action Inhibit the reuptake of serotonin Indications for use Primarily used to treat depression To treat obsessive-compulsive disorder Bulimia, migraines Panic disorder, anxiety disorders PTSD PMS Anti-depressants (SSRIs) Nursing considerations Onset of fluoxetine’s antidepressant effect develops slowly for up to 12 weeks Use caution in clients who are taking other CNS medications or who have liver dysfunction This drug Is contraindicated with MAOIs Monitor for increased suicide ideation Patients should avoid grapefruit juice Adverse/side effects Risk of suicide Worsening depression, mania Development of a potentially life-threatening serotonin syndrome or NMS-like reactions Rash Decreased appetite Contraindications Concurrent use of MAOIs, linezolid and other medications that increase serotonin levels Anti-depressants (SNRIs) Mechanism of action Inhibit the reuptake of serotonin and norepinephrine, with weak inhibition of dopamine reuptake Indications for use Treatment of major depressive disorder Nursing considerations Contraindicated with MAOIs or within 14 days of use of MAOI Dose adjustment required for use in clients with renal and/or liver disease Elderly clients are at greater risk for developing hyponatremia Use with caution with other serotonin medications Adverse/side effects Risk of suicide Worsening depression, mania Increase in blood pressure Serotonin syndrome Insomnia Anxiety Loss of appetite/weight loss Mani Elevated serum cholesterol Anti-depressants (MAOI) Client teaching Use medication as direction Dose should be tapered prior to discontinuation Increase in drowsiness or dizziness Avoid with alcohol Can cause suicidal ideation Mechanism of action Presumed to be linked to the potentiation of monoamine neurotransmitter activity in the central nervous system resulting from its inhibition of the enzyme monoamine oxidase (MAO). MAO deactivates norepinephrine, dopamine, epinephrine and serotonin. By inhibiting MAO, the levels of these transmitters rise thus creating anti-depressive effects Indications for use Treatment of major depressive disorder For patients who have not responded adequately to other antidepressants Nursing considerations Serious interactions with several medications as well as foods and beverages containing tyramine Safety has not been established with pediatric population Elderly population at increased risk for postural hypotension and serious adverse effects Misuse and dependence have been reported Withdrawal effects can continue for several weeks after discontinuation Anti-depressants (MAOI) Adverse/side effects Risk of suicide Worsening depression, mania Risk of hypertensive crisis Orthostatic hypotension hepatoxicity seizures hypoglycemia in diabetic clients restlessness headache, dizziness Client teaching Use medication as direction It may take 4 weeks to see effects of the drug Do not abruptly stop Avoid alcohol Avoid other cns depressants Avoid tyramine-containing products during use and for 2 weeks after discontinuation Signs of hypertensive crisis Examples of TCA – amitriptyline (Elavil), nortriptyline (Aventyl) Examples of SSRI- fluoxetine (Prozac), citalopram (Celexa), sertraline (Effexor) Examples of SNRI- venlafaxine (Effexor) Examples of MAOI- tranylcypromine (Parnate)