neuropharmacology.pdf

NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN NEUROPHARMACOLOGY ADAPTATION INTO PROLONGED DRUG USE The study of drugs that alter processes controlled Increased therapeutic effects [i.e. antipsychotic by the nervous system...

NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN NEUROPHARMACOLOGY ADAPTATION INTO PROLONGED DRUG USE The study of drugs that alter processes controlled Increased therapeutic effects [i.e. antipsychotic by the nervous system and antidepressants] Decreased side effects [phenobarbital, anti seizure drug that produce sedation] TOLERANCE AND PHYSICAL DEPENDANCE Tolerance ○ decreased response occurring in the course of prolonged drug use ○ Someone who uses a specific drug a lot will HOW NEURONS REGULATE OTHER CELLS gain tolerance AXONAL CONDUCTION Physical dependence Conducting an action potential down the axon of ○ state in which abrupt discontinuation of drug the neuron use will precipitate a withdrawal ○ Withdrawal syndrome: recreational use SYNAPTIC TRANSMISSION ○ Rebound Process by which information is carried across the gap between neuron and postsynaptic cells CNS STIMULANTS ADHD Dysregulation of the transmitters serotonin, norepinephrine, dopamine Characteristics: inattentiveness, inability to concentrate, restlessness, hyperactive, inability complete tasks and impulsivity CNS DRUGS Narcolepsy Used for psychiatric disorders, suppression of characterized by falling … seizures, relief of pain, production of anesthesia Unable to move and may collapse CNS contains 21 compounds that serves as AMPHETAMINES neurotransmitters Stimulant the release of NE and DA from the brain and SNs METHYLPHENIDATE Given to a child’s attention span and cognitive performance Used to treat narcolepsy BLOOD BRAIN BARRIER MODAFINIL Impedes the entry of drugs into the brain Treatment of narcolepsy Passage is limited to lipid-soluble agents or via ANALEPTICS: XANTHINE specific transport systems Stimulant respiration CHILDREN are much more sensitive to CNS drugs DOXAPRAM than adults Treatment of respiratory depression caused by drug ○ Decrease overdose and COPD Until 3 liters of oxygenation because it will lose oxygen drive (?) PARKINSONS’ DISEASE Slowly progressive neurodegenerative disorder characterized by tremor, rigidity, postural instability and slowed movement  NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN Affects the extrapyramidal system which Use with antipsychotic reduces the effectiveness of influences movement levodopa Amantadine may increase anticholinergic adverse THERAPEUTIC GOAL effects Improve the patient’s ability to carry out activities of daily life DOPAMINERGIC DRUGS: ADVERSE EFFECTS Improves bradykinesia, gait disturbance and postural instability DRUGS DEPLOYED Dopaminergic Drugs: directly/indirectly … activation of dopamine receptors Anticholinergic Agents: drugs that can block receptors for ACh NURSING PROCESS DRUGS MECHANISM OF THERAPEUTIC ACTION ROLES ASSESSMENT DOPAMINE Converted to First-line REPLACEMENT: dopamine and drug/substitute to Assess motor symptoms and the extent which they Levodopa activates dopamine interfere with activities of daily living Levodopa/ dopamine Carbidopa receptors Identify high-risk patient (cardiac, psychiatric disorders, MAOI drugs) DOPAMINE Directly activates Firstline drugs AGONISTS DA receptors Pramipexole IMPLEMENTATION Ropinirole Assist patient with dosing when needed Bromocriptine Avoid high-protein meals COMT INHIBITORS Inhibits breakdown Adjunct to Inform patient that benefits may be delayed for Entacapone of levodopa levodopa tolcapone weeks to months DOPAMINE Anti-viral but 2nd or 3rd line RELEASER promotes release drug NURSING CONDITIONS Amantadine of dopamine 1. Monitor for adverse reaction and be alert for drug MAO-B inhibitors Inhibits breakdown For newly interactions Selegiline of dopamine diagnosed patients 2. Report muscle twitching and blepharospasm [early Rasagiline signs of drug overdose] 3. Monitor vitals especially during dosage TYRAMINE REACTION adjustments Levodopa + Maoi = Hypertensive Crisis 4. Evaluate understanding drugs 5. Administer with food to prevent GI irritation [except Levodopa] 6. Withhold dose, notify physician if V/S or mental status change significantly 7. Safety precautions 8. If the patient receives a single-dose, the drug is better given at bedtime DOPAMINERGIC DRUGS: DRUG INTERACTIONS TDM: Therapeutic Drug Monitoring Reduced when taking pyrido… B6], phenytoin, benzodiazepine, reserpine and papaverine Use with MAOI increases the risk of hypertensive crisis  NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN EPILEPSY Group of disorders characterized by excessive excitability of neurons in the CNS Seizure: general term that applies to all types of epileptic events Grand mal: may cause a person to lose consciousness, this may cause them to fall to the ground, have muscle jerks or spasms, and cry out Petit mal: also known as absence seizure causes you to blank out or stare into space for a few PARTIAL FOCAL SEIZURES seconds Carbamazepine Partial: Excitation undergoes limited spread from Gabapentin the focus to adjacent cortical areas Lamotrigine Generalized: Excitation spreads widely throughout Tiagabine both hemispheres of the brain Topiramate Convulsion: abnormal motor phenomenon ABSENT SEIZURES Matinding motor movement 1. Succinimides Ethosuximide STATUS EPILEPTICUS Methsuximide If seizures Phensuximide Remove surrounding items 2. Valproic Acid Loosen clothing 3. Zosinamide Side Lying position Don't put anything in the mouth ANTI-EPILEPTIC DRUGS MECHANISM Time seizure Suppression of sodium If diagnosed no need to go to the ER Suppression of calcium influx call ambulance; 2 - 5 mins (status epilepticus), Antagonism of glutamate side of the road Potentiation of GABA DRUGS FOR SPECIFIC TYPES OF SEIZURES HYDANTOINS Inhibits neuromuscular transmission for PHENYTOIN - most commonly prescribed ○ Long term management of recurrent seizures anticonvulsant drug [epilepsy] Stabilize nerve cells to keep them from getting ○ Short-term management of acute isolated overexcited by increasing efflux or decreasing seizures influx of sodium ions ○ Emergency treatment of status epilepticus INDICATIONS: [continuous seizure state] ○ Control of tonic-clonic seizure and complex partial [DOC] MAJOR CLASSES ○ Status epilepticus ○ Prevention and treatment of seizures during neurosurgery NURSING CONSIDERATION 1. Monitor blood levels [therapeutic level: 10 - 20 mcg/mL] 2. Monitor CBC and calcium level every 6 months 3. Check V/S, ECG during IV administration  NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN 4. Administer oral forms with food to decrease GI 6. May cause leukopenia, anemia, and irritation thrombocytopenia [fatal aplastic anemia] 5. May precipitate with D5W; clear tubing first with PNSS BENZODIAZEPINES 6. PURPLE GLOVE SYNDROME - phenytoin IV push 7. 20% chances of causing gingival hyperplasia BARBITURATES PHENOBARBITAL Diazepam is restricted to acute treatment of status Effective against partial seizures and generalized of epilepticus tonic-clonic seizures but not absence seizures IV Lorazepam - DOC for acute management of Suppresses seizures by potentiating the effects of status epilepticus GABA Clonazepam - treatment for absence, atypical Can be used as a daytime sedative “sleeping pills” absence seizures Able to suppress seizures without causing generalized CNS depression ADVERSE EFFECTS NURSING CONSIDERATION Assess response to drug and … levels Monitor compliance every follow-up check up IV phenobarbital is reserved for emergency treatment - monitor RR and do not give more than 60 mg/min Do not stop the drug abruptly NURSING CONSIDERATIONS 1. Monitor RR every 5 - 15 mins and before each IMINOSTILBENES repeated IV dose CARBAMAZEPINE 2. For prolonged therapy, monitor liver, kidney and Cornerstone of epilepsy therapy hematopoietic function Active against partial seizures and tonic-clonic 3. For oral forms, check possibility of mixing with seizures but not absence seizures water, juice or carbonated beverages Suppresses neuronal discharge by delaying 4. IV Diazepam - adm no more than 5 mg/min recovery of sodium channels 5. Administer safety precautions Has fewer side effects than phenytoin and phenobarbital CARBOXYLIC ACID DERIVATIVES Rashes, hives and Steven-Johnson Syndrome [fatal inflammatory disease] can occur as adverse reactions Do not drink grapefruit as it can increase levels of this drug MECHANISM OF ACTION Suppression of neuronal firing though NURSING CONSIDERATION ○ Block sodium channels 1. Assess patient's seizure disorder before therapy ○ Blocking calcium influx and regularly there after ○ Augment inhibitory influence of GABA 2. Obtain baseline urinalysis, BUN, Liver function, INDICATIONS CBC, iron levels ○ All partial and generalized seizures 3. Therapeutic level monitoring: 4 - 12 mcg/mL ○ Bipolar disorder 4. Shake an oral suspension before measuring dose ○ Migraine 5. Never suddenly discontinue the drug when treating seizures  NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN NURSING CONSIDERATIONS CENTRALLY ACTING AGENTS Monitor liver function tests, platelet counts and prothrombin time Monitor therapeutic level 50 - 100 mcg/mL Dilute the drug with a compatible diluent if injecting IV and give over 1 hour, don't exceed 20 mg/min Avoid sudden withdrawal which may worsen seizures Monitor closely for hepatotoxicity esp. In children NURSING CONSIDERATIONS under 2 y/o taking other anticonvulsants Long term use canon result in physical and psychological dependence GABAPENTIN Monitor for hypersensitivity reactions Bind to a carrier protein and act a receptor resulting in Closely monitor CBC results increased GABA in the brain Gi with meals to prevent GI distress INDICATIONS Prepare prescription for mild analgesics to relieve ○ Partial seizures drug-induced headache ○ Treatment of pain from diabetic neuropathy Change positions slowly to avoid dizzy spells ○ Tremors associated with MS, bipolar disorder and migraine prophylaxis DIRECT ACTING AGENTS NURSING CONSIDERATIONS DANTROLENE SODIUM 1. MONITOR: patient’s serum level response to therapy Most effective for spasticity of cerebral origin [i.e. 2. ADMINISTER: safety precautions if the patient has cerebral palsy, MS, spinal cord injury, stroke] adverse effect to the drug Used for treatment of malignant hyperthermia 3. ADMINISTER: the first dose at bedtime to minimize [complication of anesthesia causing muscle effect of drowsiness, dizziness, fatigue and ataxia rigidity and high fever] REMINDERS NURSING CONSIDERATIONS Nonadherence accounts for neo… of all treatment Obtain history of pan and muscle spasms reassess failures during treatment Abrupt withdrawal can trigger seizure incidents Monitor CBC results and liver function tests Anticonvulsants cause CNS depression, do not mix If severe diarrhea, severe weakness, sensitivity with CNS depressants reactions occur withhold the dose and notify Health teaching about inactivation of oral physician contraceptives and warfarin Avoid abrupt discontinuation Traditional anticonvulsants and can harm developing fetus during the first trimester OTHERS DRUGS FOR MUSCLE SPASM BACLOFEN MUSCLE SPASM Defined as involuntary contraction of a muscle or Mimics inhibitory actions of GABA in the CNS muscle group Produces less sedation and less peripheral muscle Often painful and decreases level of functioning weakness than dantrolene DOC for spasticity CLASSES Indicated for paraplegic/quadriplegic patients with spinal cord lesions Centrally-acting Most common adverse effect is transient Direct-acting drowsiness Others  NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN NURSING CONSIDERATIONS Should be administered by personnel skilled in Place safety precautions as needed airway management Watch out for increase risk of seizures for patients NMBs precipitates if mixed with alkaline with history solutions Follow medication label for storage [usually in NEUROMUSCULAR BLOCKING DRUGS refrigerators] Relax skeletal muscles by disrupting the transmission of impulses at the motor end p… DEPOLARIZING BLOCKING DRUGS Inications Succinylcholine: acts like acetylcholine but not ○ Relax muscles during surgery inactive ACHe ○ Reduce intensity of muscles in ○ DOC for short procedures [less than 5 drug-induced seizures mins] and for orthopedic manipulations ○ Manage patients who are fighting the use Monitor baseline electrolytes and V/S of ventilator to help with breathing Measure I&O, renal function Allow effects to subside if will be given after NON-DEPOLARIZING BLOCKING DRUGS pancuronium Competitive/stabilizing drugs Give test dose before therapy - no respiratory Compete with ACh to prevent muscle from distress means good to go contracting ○ Atracurium CONTRAINDICATIONS / PRECAUTIONS ○ Cisatracurium Baclofen and dantrolene ○ Doxacurium Pregnancy risk category C ○ Mivacurium ○ pancuronium Diazepam ○ Rocuronium Controlled substance [schedule IV] ○ Vecuronium Pregnancy Risk Category D NON DEPOLARIZING AGENTS Use both of these medications cautiously in clients with impaired liver and renal function Use for Ease of passage of an endotracheal tube Decrease the amount of anesthetic required SUBSTANCE ABUSE during surgery Facilitate realigning broken bones and ABSTINENCE SYNDROME dislocated joints Withdrawing from a substance that has the Prevent muscle injury during ECT potential to cause addiction can cause abstinence syndrome. Manifestations can be NURSING PROCESS distressing and may lead to coma and death 1. Monitor patient’s baseline electrolyte levels and Occurs when clients abruptly withdraw from a V/S substance which they are physically dependent 2. Measure accurate I&O, renal function Major substances associated: alcohol, 3. Provide nerve stimulator and train of four cannabis, hallucinogens, inhalants, opioids, monitoring as ordered to confirm recovery of sedative/hypnotics, stimulants and tobacco muscle strength Substance withdrawal varies depends on the 4. Monitor RR closely until full recovery [check substance and can produce a variety of using hand grip, head lift, and ability to cough] manifestations, including gastrointestinal 5. Assess for pressure areas and breakdown distress neurological and behavioral changes, 6. Assess incomplete closure of the eyelids cardiovascular changes and seizures Administer sedatives or general anesthetics before NMBs NEUROPHARMACOLOGY: CNS DRUGS Prof. Melissa Alarzar RN ALCOHOL ABSTINENCE SUPPORT OPIOID WITHDRAWAL SUPPORT Effects of withdrawal usually start within 4 to 12 hour of the last intake of alcohol, peak after 24 to 48 hr, and subside within 5 - 7 days unless alcohol withdrawal delirium occurs Manifestations include ○ Nausea; vomiting ○ Tremors, restlessness and inability to sleep ○ Depressed mood or irritability ○ Increased heart rate, blood pressure, respiratory rate and temperature ○ Tonic - clonic seizures, illusions are also common DETOXIFICATION ABSTINENCE MAINTENANCE OPIOID ADDICTION Characteristic withdrawal syndrome occurs w/in 1 to several days after cessation of substance use Clinical findings ○ agitation , insomnia ○ Flukelike manifestations, rhinorrhea ○ Yawning, sweating and diarrhea Manifestations are non-life threatening although suicidal ideation may occur