ICL 8.1: Intro to Psychopharmacology

Question 1

what is pharmacokinetics?

Answer 1

what happens to the drug when its in the body; what the body does to the drug

it can be absorption, distribution, metabolism or elimination

Question 2

what are pharmacodynamics?

Answer 2

what the drug does to the body

Question 3

what is a substrate?

Answer 3

a substance that uses that specific enzyme

Question 4

what is an inducer?

Answer 4

a substance that induces/increases the activity of that specific enzyme, thereby decreasing levels of a concomitant substrate

ex. carbamazepine

it’s an inducer so if someone is on a medication and add CBZ to that medication, it will cause a decrease to the levels of that other medication

Question 5

what is an inhibitor?

Answer 5

a substance that inhibits/decreases the activity of that specific enzyme, thereby increasing levels of a concomitant substrate

ex. fluoxetine

it’s a cytochrome inhibitor so this is important because some drugs require metabolism to be active –> tomoxaphin which treats breast cancer needs to be metabolized so if you’re taking fluoxetine at the same time, it will decrease the levels of tomoxaphin which is bad

Question 6

how long can you write a prescription for normal meds, controlled substances, and stimulant medication?

Answer 6

1. most medications that are not controlled substances can be authorized for up to 1 year
2. schedule IV controlled substances have a maximum of 6 months of authorization like benzodiazepines or sleeping medications (except opioid pain pills cannot have refills)
3. schedule II medications (stimulant medications) can be written 3 at a time, with “do not fill until ____” for each sequential month

Question 7

what is a schedule I medication?

Answer 7

substances in this schedule have a high potential for abuse, have no currently accepted medical use in treatment in the United States, and there is a lack of accepted safety for use of the drug or other substance under medical supervision

ex. heroin, LSD, marajuana, Peyote, Methaqualone, MDMA/ecstsy

Question 8

what is a schedule II medication?

Answer 8

substances in this schedule have a high potential for abuse which may lead to severe psychological or physical dependence

ex. morphine, dilaudid, methadone, demerol, oxycontin, fentanyl, adderall, cocaines, pentobarbital, amobarbital

Question 9

what is a schedule III medication?

Answer 9

substances in this schedule have a potential for abuse less than substances in schedules I or II and abuse may lead to moderate or low physical dependence or high psychological dependence

ex. Vicodin, Tylenol with codeine, Buprenorphine, Suboxone. Ketamine, Anabolic steroids

Question 10

what is a schedule IV medication?

Answer 10

substances in this schedule have a low potential for abuse relative to substances in schedule III

ex. benzodiazepines, ambien, sonata, lunesta

Question 11

what is a schedule V medication?

Answer 11

substances in this schedule have a low potential for abuse relative to substances listed in schedule IV and consist primarily of preparations containing limited quantities of certain narcotics – these are generally used for antitussive, antidiarrheal, and analgesic purposes

ex. robitussin with codeine, phenergan with codeine

Question 12

what are the various routes of drug delivery?

Answer 12

1. intramuscular
2. IV
3. subcutaneous
4. inhalation
5. topical
6. oral
7. rectal

Question 13

what is first pass metabolism?

Answer 13

when an orally administered drug passes for the first time from the gut into the hepatic portal system and enters the liver, it can undergo first pass “Phase 1” metabolism by cytochrome P450 system

during this time a percent of the drug is changed from the original parent compound into some intermediate metabolite

abnormalities in the GI tract and hepatic system can affect CYP enzymes and thus can affect most psychotropic medications

Question 14

what is second pass metabolism?

Answer 14

phase II (2nd pass) is when conjugation takes place and the drug is further metabolized in the liver to aid its future elimination

some drugs don’t use cytochromes much but do conjugation (like benzos)

through glucuronidation, Lamotrigine + Valproate together can cause an increase in Lamotrigine (SJS) and a decrease in valproate

depot (IM) injections are considered “parenteral” and bypass 1st pass metabolism and goes directly into inferior vena cava (then right heart, then lung, then left heart, then out to body)

Question 15

what are CYP450 enzymes?

Answer 15

a group of 57 proteins, each coded by a different gene; divided into 5 subfamilies = 1A2, 3A4, 2C19, 2E1, and 2D6

more than 90% of all drugs are metabolized by only a few of the CYP enzymes = 1A2, 2B6, 2C8/9, 2C19, 2D6, 2E1, and 3A4/5

Question 16

what’s the difference between an active and a prodrug?

Answer 16

active = parent drug is already active and therefore metabolizing it makes it inactive

prodrug = parent drug is inactive by itself and therefore metabolizing it makes it active

Question 17

what substances induce the CYP1A2 system?

Answer 17

1. tobacco smoking
2. vegetables like broccoli, cabbage, brussel sprouts
3. char-grilled meat

so if you’re on a medication that gets metabolized by CYP1A2 you have to make sure the patient isn’t smoking or eating a lot of vegetables because they induce the CYP1A2 enzyme system

Question 18

what are the age related issues involved with the pharmacokinetics of medications?

Answer 18

absorption is relatively unaffected by aging

IV medications should be used with caution, as peak doses can cause side effects such as low blood pressure and in an older frail patient can cause stroke

volume of distribution of medication is significantly affected by aging. Less as you age

oxidization reactions are affected by normal aging- clinically most important is CYP-P450 system

clearance is also decreased with aging

watch out for liver and kidney functions

Question 19

what are the pediatric related issues involved with the pharmacokinetics of medications?

Answer 19

the absorption, distribution, metabolism, and excretion of drugs and drug pharmacokinetic profiles can be different from that of the adult population

although children have smaller body size than adults, the relative mass of liver and kidney tissue is greater when adjusted for body weight

children also have relatively more body water, less fat, and less plasma albumin to which drugs can bind –> consequently, the volume of distribution of a drug tends to be greater in children than in adults

children have greater drug extraction during the first pass through the liver, lower bioavailability, and faster metabolism and elimination

this means that simply decreasing adult doses based on child weight may result in under-treatment. In adolescence, together with a marked growth in body size, there is a redistribution of the body compartments

absolute clearance is usually lower in children than in adults, but weight-adjusted clearance is greater. Because of the faster elimination, the drug plasma half-life can be shorter in children than in adults

Question 20

what are the STEPS of medication selection?

Answer 20

Safety

Tolerability

Efficacy

Payment

Simplicity

Question 21

what is the time course of the efficacy of a medication?

Answer 21

different classes of psychotropic medications take different times demonstrate efficacy!!!

Question 22

what is the time course to efficacy of antidepressants?

Answer 22

2 weeks for tolerability to get over the GI effects, etc.

4-6 weeks for 50% efficacy

12 weeks for full effects!!

Question 23

what is the time course to efficacy of antipsychotics?

Answer 23

1 week for tolerability

1-2 weeks for efficacy

4 weeks for full effects

usually work through the dopamine system and they’re used for psychotic disorders, most bipolar disorders, and some for depression!

Question 24

what is the time course to efficacy of benzodiazepines?

Answer 24

almost immediate

can be used PRN for anxiety

Question 25

what is SIGECAPS?

Answer 25

Sleep

Insomnia

Guilt

Energy

Concentration

Appetite

Psychomotor retardation

Suicidality

Question 26

what comorbidities should you ask about before prescribing medications?

Answer 26

1. SIGECAPS
2. anxiety
3. bipolar/manic
4. psychotic = hallucinations, paranoia, delusions
5. stressors = social, physical, work, home, medical
6. substance use
7. psychiatric
8. medical review of systems

Question 27

what is DIGFAST?

Answer 27

bipolar/manic symptoms

Distractibility

Irresponsibility

Grandiosity

Flight of ideas

Activity increases

Sleep deficit

Talkativeness

decreased appetite and racing thoughts too

Question 28

which psychological illnesses require medications?

Answer 28

1. psychotic disorders = YES
2. bipolar disorders = mostly yes
3. depressive disorders = maybe yes
4. anxiety disorders = maybe yes
5. ADHD = maybe yes

other than psychotic disorders and probably bipolar disorder, if an illness (one diagnosis) is mild to moderate in severity, behavioural interventions are generally considered first line (especially in children); if severe, the answer is YES, NEEDS MEDS

Question 29

what medical evaluation should you do before prescribing a medication for a psychiatric illness?

Answer 29

1. rule out toxicology reasons like drugs
2. rule out other medical causes of psychiatric symptoms
3. then consider psychiatric reasons