Introduction to Psychopharmacology

Question 1

What determines a patient’s response /tolerance in one drug over another?

Answer 1

Individual patients may better respond to or tolerate one agent over another because of differences in each drug’s pharmacokinetics
1. Absorption
2. Distribution
3. Metabolism
4. Excretion

Question 2

Factors that may influence drug choice?

Answer 2

1. Patient’s personal/family hx of response/tolerance to a drug
2. Potential for interaction with/concurrent medications
3. Patient preference
4. Comorbid medical conditions
5. Comorbid psychiatric conditions

Question 3

Dangers of polypharmacy?

Answer 3

• Polypharmacy increases risk of drug-drug interactions and should be minimized/avoided
• Number of medications may be reduced by making use of drug’s secondary pharmacological effects
  e.g. prescribing a sedating agent to someone who has insomnia
  Note: Where possible patients need to be involved in drug selection

Question 4

Strategies to maximize medication adherence?

Answer 4

1. Patient education (adverse effects, speed of onset of therapeutic effect, tolerance)
2. Arrange a convenient dosing schedule
3. Minimize adverse effects
4. Check for patient adherence
5. Schedule office/phone visits to discuss adherence and adverse effects for newly prescribed drugs
6. Reduce pill burden where necessary

Question 5

Drug Metabolism in pharmacokinetics?

Answer 5

The most common pharmacokinetic drug–drug interaction involves changes in the CYP-mediated metabolism of the substrate drug by an interacting drug
1. Enzyme inducers - will decrease amount of circulating parent drug
2. Enzyme inhibitors - leading to high circulating drug levels
Note: Attempt to avoid medications that significantly inhibit or induce CYP enzymes

Question 6

Drug Absorption in pharmacokinetics?

Answer 6

Many orally administered drugs, including a number of psychotropics, have poor bioavailability due to extensive first-pass metabolism

Question 7

Drug Distribution in pharmacokinetics?

Answer 7

Changes in drug protein binding, either disease-induced or the result of a protein-binding drug interaction

Question 8

Drug Excretion in pharmacokinetics?

Answer 8

Drug interactions altering renal drug elimination may be clinically significant if the parent drug or its active metabolite undergoes renal excretion
E.g. some antihypertensive agents (thiazide diuretics, angiotensin- converting enzyme inhibitors), decrease GFR and impair renal elimination, which may lead to lithium toxicity

Question 9

Pharmacodynamic drug interactions?

Answer 9

1. Occur when drugs with similar or opposing effects are combined
2. Leads to addition or antagonism of the pharmacological and toxic effects of each
3. More common with compromised physiological function
   e.g. in cardiovascular disease, or the elderly
4. For example multiple drugs with anticholinergic activity may exacerbate cognitive impairment in the elderly

Question 10

Anticholinergic adverse effects?

Answer 10

1. dry mouth
2. constipation
3. blurred vision, mydriasis
4. urinary retention
5. tachycardia

Question 11

Diffuse neurotransmitters?

Answer 11

1. Glutamate
2. GABA

Question 12

Circumscribed neurotransmitters?

Answer 12

1. Serotonergic
2. Noradrenergic
3. Dopaminergic
4. Histaminergic
5. Cholinergic