L15 Drugs for Dementia and Parkinson's Disease Flashcards
Learning Outcomes (for general perusal)
- Describe the essential features of dementia and Parkinson’s disease
- Describe the neurotransmitters involved in the action of drugs used to treat dementia and Parkinson’s disease
- Describe the mode of action, desired and adverse effects of these drugs
- Describe how these drugs are used
- Relate the pathophysiology of Parkinson’s disease with the pharmacological rationale for treatment.
- Pharmacological approaches to the treatment of dementias and evidence for the efficacy of inhibitors of acetylcholinesterase.
Outline the pathological processes causing neuronal cell death
What is the protein called in
- Alzheimer’s Disease
- Parkinson’s Disease
- Misfolding of normal physiological proteins
- which can aggregate to form oligomers
- which aggregate further to form neurotoxic insoluble aggregates
- Beta amyloid protein
- Alpha synuclein protein
What are the mechanisms of neuronal cell death?
- Excitotoxicity - mainly through activation of NMDA receptors
- Apoptosis
- Oxidative Stress - hypoxia
What is Dementia?
Global term and refers to a set of symptoms with decline in memory and thinking of a degree sufficient to impair functioning in daily living.
Symptoms must be present for 6 months or more
Associated changes in personality and behaviour
What are the different types of dementia?
Alzheimer’s Disease - 60%
Vascular Dementia - 15-20%
Lewy Body Dementia - 15%
Fronto-temporal Dementia
Rarer Dementias (Huntington’s Disease, CJD)
How does a person with Alzhiemer’s present?
- Early changes in mood and memory
- Gradual decline in short term memory
Other features then begin to appear:
- Loss of ability to conduct complex tasks e.g. finances
- Impaired concentration, disorientation
- Behavioural and psychological symptoms emerge
- Increased dependency on others
Describe the pathogenesis of Alzhiemer’s Disease
- Amyloid plaques, neurofibrillary tangles
- Gliosis. Loss of neurones
- Reduction of the cerebral cortex subcortical white matter.
- Hippocampus and temporo-parietal regions affected firstly
Pathogenesis of Alzhiemer’s Disease
What is the ‘Amyloid Cascade Hypothesis’?
- Physiologically
- Pathologically
- Amyloid Precursor Protein (APP) is cleaved by α-secretase to produce soluble Amyloid Precursor Protein (sAPP)
- Amyloid Precursor Protein is abnormally cleaved by β-secretase or ɤ-secretase
- To form Beta-amyloid peptide (Aβ)
- To form oligomers and then amyloid plaques (extracelluar)
Pathogenesis of Alzhiemer’s Disease
How are neurofibrillary tangles created?
- The microtubule protein, Tau, is phosphorylated
- It dissociates from microtubules to form paired helical filaments and then neurofibrillary tangles (intracellular)
- NF tangles result in neuronal death
What are the principle neurotransmitters in Alzheimer’s disease?
-
Acetylcholine
- depletion of cholingeric neurons is the primary abnormality
- Choline acetyl transferase and choline are all reduced
- Noradrenaline - reduced in cortex and hippocampus
- Serotonin - Serotonergic neuron loss in the frontal and temporal lobes
- GABA
Cholinergic neurotransmission
- What is Acetylcholine synthesized from?
- What catalyses the reaction?
- What are the two types of receptors?
- What breaks down Ach in the synpase
- Acetyl CoA and Choline
- Choline acetyltransferase
- Nicotinic and muscarinic
- Acetylcholinesterase
What are the drugs used to treat Alzheimer’s Disease?
-
Acetylcholinesterase Inhibitors
- Donepezil, Rivastigmine, Galantamine
-
NMDA Antagonist
- Memantine
Acetylcholinesterase Inhibitors
- How do they act?
- Name three
- Which shows R modulation?
- What is the chemical class of
- Donepezil
- Rivastigmine
- Galantamine
- They all inhibit acetylcholinesterase, but which also acts to inhibit butyrylcholinesterase
- Which has the longest half life?
- What are the elimination pathways?
- Which have metabolism by cytochrome P450?
- All have caution in Hepatic impairment, what is another caution in R?
- delay the degradation of acetylcholine released at the synapse, prolonging it’s effectiveness. (most widely studied)
- Donepezil, Rivastigmine, Galantamine
- Galantamine
- Chemical Class
- Piperidine Alkaloid
- Carbamate
- Phenanthrene
- Rivastigmine
- Donepezil (70) (R=1, G=6)
- D= Liver, R= Kidney, G = 50% Kidney
- D and G
- Renal Impairment
Acetylcholinesterase Inhibitors
- Give some adverse effects
- Give some cautions
- Nausea, vomiting, diarrhoea
Insomnia, agitation
Syncope, bradycardia, heart block
Muscle cramps
Rarely EPS
- Sick sinus syndrome/conduction abnormalities
Peptic ulceration
Asthma/COPD
Glutamate in Alzheimer’s Disease
What is the role of glutamate?
A neurotransmitter turned neurotoxin
- What type of drug is Memantine?
- What are it’s effects?
- What are the side effects?
- A NMDA antagonist (glutamate receptor)
- Modest improvement in cognition in moderate to severe Alzheimer’s disease. Long half life.
- Constipation
Hypertension
Drowsiness
Seizures (rarely)
Pancreatitis