CNS Medication

Question 1

Relationship between fat solubility and BBB entry

Answer 1

THe more fat soluble a drug is the better the membrane permeability of the BBB

Question 2

Polarisation and depolarisation

Answer 2

Polarised- negative
Depolarised- positive

Question 3

What ions are responsible for de-polarisation

Answer 3

NA+ and Ca++

Question 4

RE-polarisation

Answer 4

K+ leaves the cell and Cl- come into the cell making it repolarised.

Question 5

Neurotransmitter regulation

Answer 5

Dopamine vesicles attach dopamine to the pre-synaptic membrane and then it diffuses into the synpatic cleft to bind onto dopamine recpetors.

Dopamine re uptake transporter is responsible for re-absorption of dopamine from the synaptic cleft

Question 6

Anti-epileptics: Inhibition of excitatory neurotranmission

Answer 6

Seizures often result from excessive excitatory activity, primarily mediated by glutamate. AEDs reduce this activity by:

Blocking voltage-gated sodium channels:
These drugs prevent the initiation and propagation of action potentials in neurons.

Inhibiting voltage-gated calcium channels:
Reduces neurotransmitter release by limiting calcium influx.

Question 7

Examples of NA+ channel blockers and Ca++ channel blockers

Answer 7

Na+ channel blockers:
Phenytoin, Carbamazepine, Lamotrigine.

Ca++ channel blockers:
Gabapentin, Pregabalin.

Question 8

Anti-epilpetic drugs :
Enhancement of Inhibitory Neurotransmission

Answer 8

Increasing GABA activity helps suppress neuronal excitability:

GABA receptor agonists:
Directly enhance the inhibitory effect of GABA.

GABA reuptake inhibitors:
Increase GABA levels in the synaptic cleft.

GABA transaminase inhibitors:
Inhibit the breakdown of GABA, prolonging its effect.

Question 9

Common GABA receptor agonists

Answer 9

Benzodiazepines (e.g., Diazepam, Lorazepam), Barbiturates (e.g., Phenobarbital).

Question 10

Common GABA reuptake inhibitors

Answer 10

Tiagabine

Question 11

Common GABA transaminase inhibitors

Answer 11

Vigabatrin

Question 12

What do anti-epileptic drugs(AEDs) do

Answer 12

work by modulating neuronal excitability and reducing the likelihood of seizures

Question 13

General AED Adverse effects

Answer 13

• CNS
  E.g. Headache, hallucination, speech impairments, depression
• GI
  E.g. Nausea, vomiting, diarrhoea Dry mouth
• Cardiac
  Arrhythmias, tachycardia, palpitations (ectopics)
• Haemopoetic
  Lupus like effects, Leucopenia, thrombocytopenia

Question 14

Hematologic side effects of AEDs

Answer 14

Aneamia (low RBC)- shortness of breath, pale

Leukopenia (Low WBC)- Risk of infection

Thrombocytopenia- increased bruising, bleeding from mucous membrane

Question 15

specific consideration of certain AEDs

Answer 15

• CARBAMAZEPINE
  TAKE WITH FOOD
  PHOTOSENSITIVITY
  BONE MARROW DEPRESSION
• Sodium valproate (Epilim)
  LFT assessment prior and 6 months after initiation of treatment
  FBC and Clotting (particularly if Pt going to Surgery)
  Possible risk of pancreatitis

Question 16

Drug resistance

Answer 16

Disease severity:
* High seizure frequency

Disease and drug altering factor:
* Inflammation
* Excitatory receptor changes
* alteration of drug efflux changes

Genetic influence:
* MRP2 (drug efflux pump polymorphisms)

Question 17

What is Parkinsons

Answer 17

Parkinson’s disease is a progressive neurological disorder that primarily affects movement. It occurs when nerve cells in the brain, particularly in an area called the substantia nigra, become damaged or die, leading to a deficiency of dopamine,

Question 18

Common meds used in parkinsons

Answer 18

Dopaminergic drugs:
Levodopa

Dopamine agonists:
Stimulate dopamine receptors(Pramipexole, Ropinirole, Bromocriptine)

Enzyme inhibitors:
Inhibit dopamine breakdown by monoamine oxidase-B.
Examples: Selegiline, Rasagiline.

Prolong the effect of L-DOPA by inhibiting catechol-O-methyltransferase (COMT)
Examples: Entacapone, Tolcapone.

NMDA Receptor Antagonists
Amantadine:
Provides symptomatic relief by increasing dopamine release and reducing reuptake.

Anticholinergic Drugs
Reduce relative acetylcholine overactivity in the basal ganglia.
Examples: Benztropine, Trihexyphenidyl.

Question 19

Common Side Effects of PD Drugs

Answer 19

Levodopa-induced dyskinesia (involuntary movements).
Dopamine agonists: Hallucinations, impulse control disorders (e.g., gambling, hypersexuality).
Anticholinergics: Cognitive impairment, dry mouth.
MAO-B/COMT inhibitors: Nausea, diarrhea.