Central Nervous System drugs Flashcards
Central Nervous System Drugs
Used for psychiatric disorders, suppression of seizures, relief of pain, production of anesthesia
21 compounds that serve as neurotransmitters contain in CNS
MONOAMINE:
- Dopamine
- Epinephrine
- Serotonin
AMINO ACID:
- Aspartate
- GABA(Gamma-Aminobutyric Acid)
- Glutamate Glycine
PURINE:
- Adenosine
- Adenosine monophosphate
- Adenosine triphosphate
OPIOID PEPTIDES:
- Dynorphins
- Endorphins
- Enkephalins
NONOPIOID PEPTIDES:
- Neurotensin
- Oxytocin
- Somatostatin
- Substance P
- Vasopressin
OTHERS:
- Acetylcholine
- Histamine
- GABA (Gamma-Aminobutyric Acid)
Blood Brain Barrier, its definition and function
- A network of blood vessels and tissue that is made up of closely spaced cells and helps keep harmful substances from reaching the brain.
- The blood-brain barrier (BBB) is the specialized system of brain microvascular endothelial cells (BMVEC) that shields the brain from toxic substances in the blood, supplies brain tissues with nutrients, and filters harmful compounds from the brain back to the bloodstream.
- Impedes the entry of drugs into the brain
- Passage is limited to lipid-soluble agents or via specific transport systems
- CHILDREN are much more sensitive to CNS drugs than adults
Adaptation to prolonged drug use
- Increased therapeutic effects (i.e. antipsychotic and antidepressants)
- Decreased side effects (phenobarbital, antileisure drug that produces sedation)
- Tolerance and Physical Dependence:
Tolerance –decreased response occurring in the course of prolonged drug use
Physical Dependence –state in which abrupt discontinuation of drug use will precipitate a withdrawal syndrome
CNS stimulants and Amphetamines
- ADHD (Attention Deficit/ Hyperactivity Disorder)
> Dysregulation of the transmitters serotonin, norepinephrine, dopamine
Characteristics: inattentiveness, inability to concentrate, restlessness, hyperactivity, inability to complete tasks and impulsivity
- NARCOLEPSY
- Characterized by falling asleep during normal waking activities [driving/ talking]
- Unable to move and may collapse
CNS stimulants: Amphetamines
- Stimulate the release of Norepinephrine(NE) and Dopamine(DA) from the brain and sympathetic nervous system(SNS)
Methylphenidate:
- Given to increase child’s attention span and cognitive performance
- Used to treat narcolepsy
Modafinil:
= Treatment of narcolepsy
Parkinson’s disease
- Slowly progressive neurodegenerative disorder characterized by tremor, rigidity, postural instability and slowed movement
- Affects the extrapyramidal system which influences movement
Drug for Parkinson’s disease
Therapeutic goal
Drugs deployed
Therapeutic goal:
- Improve the patient’s ability to carry out activities of dally life
- Improves bradykinesia, gait disturbance and postural instability
Drugs deployed:
= Dopaminergic drugs –directly/ indirectly cause activation of dopamine receptors
= Anticholinergic Agents –drugs that block receptors for acetylcholine(ACh)
List of drugs = mechanism of action = therapeutic Role
- DOPAMINE REPLACEMENT:
Levodopa
Levodopa/Carbidopa
= Converted to Dopamine and activates dopamine receptors
= First-line drug/ supplement to dopamine agonist - DOPAMINE AGONISTS: Pramipexole
Ropinirole
Bromocriptine
= Directly activates DA receptors
= First line drugs - COMT(catechol-o-methyl transferase) INHIBITORS: Entacapone
tolcapone
= Inhibits breakdown of levodopa
= Adjunct to levodopa - DOPAMINE RELEASER:
Amantadine
= Anti-viral but promotes release of dopamine
= 2ndor 3rdline drug - MAO(Monoamine oxidase)-B inhibitors
- Selegiline
- Rasagiline
= Inhibits breakdown of dopamine
= For newly diagnosed patients
Dopaminergic Drugs: Drug Interactions and Adverse Effect
- Reduced when taking pyridoxine [VIT B6], phenytoin, benzodiazepines, reserpine and papaverine
- Use with MAOI increases the risk of hypertensive crisis
- Use with antipsychotic reduces the effectiveness of levodopa
- Amantadine may increase anticholinergic adverse effects
Drugs:
1. Levodopa:
- Nausea and vomiting
- Orthostatic
- hypotension
- Anorexia
- Neuroleptic malignant syndrome
- Arrhythmias
- Confusion
2. Amantadine:
- Orthostatic
- hypotension
- Constipation
3. Bromocriptine:
- Orthostatic
- hypotension
- Ventricular tachycardia
- Bradycardia
- Worsening angina
4. Selegiline
- Headache
- Insomnia
- Dizziness
- Nausea
- arrhythmia
5. Ropinirole:
-Orthostatic
-hypotension
- Dizziness
- Confusion
- Insomnia
Dopaminergic Drugs: Nursing Considerations:
1.Monitor for adverse reactions and be alert for drug interactions
2.Report muscle twitching and blepharospasm [early signs of drug overdose]
3.Monitor vitals especially during dosage adjustments
4.Evaluate understanding of 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
Epilepsy
- Group of disorders characterized by excessive excitability of neurons in the CNS
- SEIZURE –general term that applies to all types of epileptic events
- CONVULSION –abnormal motor phenomenon
- Partial Seizure - Excitation undergoes limited spread from the focus to adjacent cortical areas
- Generalized Seizures - Excitation spreads widely throughout both hemispheres of the brain.
Drugs for specific types of seizures
- Inhibits neuromuscular transmission for
- Long term management of recurrent seizures [epilepsy]
- Short-term management of acute isolated seizures
- Emergency treatment of status epilepticus [continuous seizure state]
Major classes of seizures drugs
- Hydantoins
- Barbiturates
3.Iminostilbenes - Benzodiazepines
- Carboxylic acid derivatives
- 1-(aminoethyl) cyclohexane acetic acid
- Phenyltriazine
- Carboxamide
- Sulfamate-substituted monosaccharides
- Succinimides
- Sulfonamides
Drugs for Partial focal Seizures
- Carbamazepine
- Gabapentin
- Lamotrigine
- Tiagabine
- Topiramate
Drugs for Absent Seizures
- Succinimides
- Ethosuximide
- Methsuximide
- Phensuximide - Valproic Acid
- Zosinamide
seizure medication:
- Hydantoins/ Phenytoin drugs and nursing considerations
- Barbiturate and nursing consideration
- Iminostilbenes and nursing consideration
- PHENYTOIN –most commonly prescribed anticonvulsant drug
> Stabilize nerve cells to keep them from getting overexcited by increasing efflux or decreasing influx of sodium ions
INDICATIONS:
- Control of tonic-clonic seizure and complex partial seizures [DOC]
- Status epilepticus
- Prevention and treatment of seizures during neurosurge
Nursing Considerations:
(Ex. DIlantin/brand name)
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
4.Administer oral forms with food to decrease GI irritation
5.May precipitate with D5W; clear tubing first with PNSS
6.PURPLE GLOVE SYNDROME –phenytoin IV push
7.20% chances of causing gingival hyperplasia
- PHENOBARBITAL
- Effective against partial seizures and generalized tonic-clonicseizures but not absence seizures
- Suppresses seizures by potentiating the effects of GABA
- Can be used as daytime sedative “sleeping pills”
- Able to suppress seizures without causing generalized CNS depression
Nursing Considerations:
1. Assess response to drug and serum levels
- monitor compliance every follow-up checkup
- IV phenobarbital is reserved for emergency treatment –monitor RR and do not give more than 60mg/min
- Do not stop the drug abruptly
- CARBAMAZEPINE
- Cornerstone of epilepsy therapy
- Active against partial seizures and tonic-clonicseizures but not absence seizures
- Suppresses neuronal discharge by delaying recovery of sodium channels
- Has fewer side effects than phenytoin and phenobarbital
- Rashes, hives and Steven-Johnson Sydrome[fatal inflammatory disease] can occur as adverse reactions
- Do not drink grapefruit juice as it can increase levels of this drug
Nursing Considerations:
1.Assess patient’s seizure disorder before therapy and regularly thereafter
2.Obtain baseline urinalysis, BUN, Liver function, CBC, iron levels
3.Therapeutic level monitoring: 4-12 mcg/mL
4.Shake an oral suspension before measuring dose
5.Never suddenly discontinue the drug when treating seizures
6.May cause leukopenia, anemia and thrombocytopenia [fatal aplastic anemia]
