CNS & GI block 4 Flashcards
What are neuronal signals in the brain control?
Breathing, movements, thoughts and emotions.
Illnesses associated with dysfunction of the brain.
Schizophrenia, depression, anxiety and Parkinsonism associated with chemical transmitter imbalances/changes in the brain.
brain neurotransmitters
- noradrenaline (norepinephrine)
- dopamine
- acetylcholine
- 5-hydroxytryptamine (5-HT, serotonin)
- gamma-amino butyric acid GABA
- glutamate (an excitatory amino acid)
Noradrenaline (NA) brain function and illnesses
-Arousal, sleep, mood, appetite, hormone release, body temp -Depression, insomnia, eating disorders, narcolepsy, ADD
Dopamine (D) brain function and illnesses
-Skeletal muscle movement, behaviour, emesis, hormone release -Parkinson’s disease, schizophrenia, aberrant behaviour, psychoses; vomiting
Serotonin
5-hydroxytryptamine
(5-HT)
brain function and illnesses
-As for NA plus behaviour, pain transmission, emesis -Depression, ADD, headaches, eating disorders, insomnia; vomiting
Acetylcholine brain function and illnesses
-Cognition, skeletal muscle movement, memory, consciousness -Parkinson’s disease, dementia
Gamma-amino butyric
acid (GABA) brain function and illnesses
-Motor control, memory, consciousness -Anxiety, insomnia, aberrant behaviour, epilepsy
Glutamate brain function and illnesses
-Memory, learning
-Alzheimer’s, stroke,
Huntington’s,
epilepsy, ?depression
How does neurotransmitter work?
A signal travels to the axon terminal, neurotransmitter is released from the storage vesicles into the synapse. neurotransmitter must cross the synapse and bind to its specific receptor in order to transfer message from a neuron to effector tissue.
Where is neurotransmitter stored?
storage vesicles
What happens to remaining neurotransmitter in the synaptic space?
it is either degraded by enzymes found in the area or it re enters the neuron and stored in the storage vesicles to be use again.
Parkinson’s disease chemical Imbalance/alterations
in neurotransmitter in levels
Low dopamine and high
acetylcholine activity
Anxiety/Insomnia chemical Imbalance/alterations
in neurotransmitter in levels
High glutamate, low GABA and low
serotonin activity
Psychoses; Schizophrenia chemical Imbalance/alterations
in neurotransmitter in levels
High dopamine activity
Epilepsy chemical Imbalance/alterations
in neurotransmitter in levels
High glutamate and low GABA
activity
Mode of action of antidepressant drugs
Increase/boost levels and/or activity of the excitatory
neurotransmitters - serotonin, noradrenaline
- has different adverse effect
- responses may differ between individuals.
Antidepressant groups
SSRIs- Selective serotonin reuptake inhibitors
TCAs- tricyclic antidepressant.
MAOIs- Monoamine oxidase inhibitors
RIMAs- Reversible Monoamine Oxidase Inhibitor Antidepressants
Newer antidepressant
SNRIs- Serotonin and noradrenaline reuptake inhibitor
TCAs- Tetracyclic antidepressants
NRIs- Noradrenaline re-uptake inhibitors
NaSSA- Noradrenergic and specific serotonergic antidepressant
Drug examples of SSRIs
- fluoxetine
- citalopram
- sertraline
- paroxetine
Drug examples of TCAs
-amitriptyline
-nortriptyline
-doxepin
-dosulepin
(dothiepin)
Drug examples of RIMAs
-moclobemide
Drug examples of MAOIs
- tranylcypromine
- phenelzine
What are some adverse effects of TCAs?
anticholinergic; antiadrenergic (postural
hypotension) antihistaminic (sedative);
weight gain; cardiac arrhythmias
What are some adverse effects of MAOIs?
anticholinergic; risk of hypo-
(antiadrenergic) and hypertensive
responses (hypertensive crisis); sedation
What are some adverse effects of RIMAs?
lower risk of adrenergic; nausea;
insomnia; dizziness
What are some adverse effects of SSRIs?
nausea; insomnia; sexual dysfunction
What are some adverse effects of SNRIs?
Similar to SSRIs – GI symptoms, sexual
dysfunction, headache, anxiety
But also hypertension, tachycardia (due to
inhibition of noradrenaline reuptake)
Drug interactions to watch out for TCAs
Other antidepressants; antimuscarinics;
hypnotics; anxiolytics; anaesthetics;
antihypertensives; caution with
anticonvulsants
Drug interactions to watch out for MAOIs
Sympathomimetics (e.g. phenylephrine,
dopamine, adrenaline, etc); other
antidepressants, antihistamines; hypnotics;
anxiolytics
Drug interactions to watch out for SSRIs
Other antidepressants; anticonvulsants;
antipsychotics; other drugs that increase
serotonin (e.g. St John’s Wort, tramadol, etc)
What happens when there’s too much neurotransmission?
- neurons overexcited
- increased neurotransmitters or receptors
- increased neurotransmitter activity
What happens when there’s too little neurotransmission?
- neurons not being excited
- decreased neurotransmitters or receptors
- decreased neurotransmitter activity
Two ways that drugs can help diseases where chemical imbalances occur are:
- Drugs can be designed to enhance the activity of a neurotransmitter by
acting on different areas of the neurotransmission pathway
-Drugs can be designed to block the neurotransmitter’s action or
response.
CNS cause variety of side effects
adverse effects are dependent on where the receptors for the neurotransmitter are located. the drug will act on the area of the brain that is required for therapeutically.
Antipsychotic drugs also called
• major tranquillisers
• neuroleptics
it modify abnormal psychotic
behaviour
What is the first generation of antipsychotics medication?
Typical antipsychotics
- Phenothiazines-chlorpromazine, pericyazine, fluphenazine
- Butyrophenones- haloperidol
What is the second generation of antipsychotics medication?
Atypical antipsychotic
- clozapine (oral liq, tablet)
- olanzapine (inj, tablet, tablet, depot inj)
- quetiapine (tablet)
- risperidone
What are some adverse effects of antipsychotic medications?
- Extrapyramidal effects
- Postural hypotension
- Anticholinergic
- Sedation
- Weight gain
- Endocrine effects - e.g. hyperprolactinaemia
- Neuroleptic Malignant Syndrome (NMS)
What are some adverse effects of extrapyramidal
-Akathisia - restlessness, fidgety
-Dystonia – muscle spasms, wry neck,
torticollis
-Oculogyric crisis - upward rolling of
eye balls
-Parkinsonism - fine tremors, bradykinesia,
drooling, shuffling gait
-Tardive dyskinesia - irreversible, occurs
with long term use, stereotyped
involuntary movements
Time frame of adverse effects
-Initial adverse effects (hours, days).. Sedation, postural hypotension, anticholinergic, acute dystonic reactions -Initial weeks - months… Akathisia, Parkinsonism, weight gain, endocrine effects -After longer term treatment Tardive dyskinesia – irreversible
Atypical antipsychotics - adverse effects
- Weight gain, dyslipidaemia
- T2DM
- Acute severe hypertension
Key concerns with ALL antipsychotics
- managing adverse effects
- compliance
- limited response
- recurrence of symptoms
- monitor of BG,risk factors
- neuroleptic malignant syndrome
what is mood stabilisers
medications used for people who cycle between mood swings. eg depression and bipolar
Mood stabiliser drugs include
lithium carbonate, carbamazepine and sodium valproate and lamotrigine Lithium is the best-reduce noradrenaline
What is lithium?
- Controls both manic and depressive state
- Takes about a week to reach therapeutic levels
Contraindications of lithium
pregnancy, lactation, cardiac and renal
insufficiency
-Narrow therapeutic index drug. Need for very strict monitoring
How is lithium distributed?
Lithium distributes itself in both intracellular and
extracellular spaces like sodium and impedes normal
functioning.
How is lithium treated in the body?
Lithium is treated like sodium as they have similar chemical structure
Symptoms of lithium toxicity
-Initially – slight nervousness, abdominal pain, anorexia,
vomiting, diarrhoea
-Potentially fatal outcome- cardiovascular, renal, failure
What are involve in treatment for depression?
Pharmacological and psychosocial interventions. for severe depression, electroconvulsive therapy may need to be used as well.
What is psychosis?
a disordered thinking and disturbed emotional tome. it is a symptom not a disease
What is neurosis?
a thinking patterns which are normal but disturbed emotional tone
Antipsychotic drugs for schizophrenia positive type symptoms includes?
acute illness, with delusions, hallucinations, incongruous behaviour. This type of manifestation is responsive to antipsychotics.
Antipsychotic drugs for schizophrenia negative type symptoms includes?
chronic illness, i.e. apathy, lack of motivation, social withdrawal, and is usually less responsive to antipsychotics.
commonly used anxiolytics and hypnotics drugs for treatment of anxiety and sleep disorders.
- triazolam
- midazolam
- diazepam
- clonazepam
- zopiclone
barbiturates
caused problems of dependency, tolerance, drug interactions and were potentially fatal in overdose.