ICL 8.1: Intro to Psychopharmacology Flashcards
what is pharmacokinetics?
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
what are pharmacodynamics?
what the drug does to the body
what is a substrate?
a substance that uses that specific enzyme
what is an inducer?
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
what is an inhibitor?
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
how long can you write a prescription for normal meds, controlled substances, and stimulant medication?
- most medications that are not controlled substances can be authorized for up to 1 year
- schedule IV controlled substances have a maximum of 6 months of authorization like benzodiazepines or sleeping medications (except opioid pain pills cannot have refills)
- schedule II medications (stimulant medications) can be written 3 at a time, with “do not fill until ____” for each sequential month
what is a schedule I medication?
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
what is a schedule II medication?
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
what is a schedule III medication?
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
what is a schedule IV medication?
substances in this schedule have a low potential for abuse relative to substances in schedule III
ex. benzodiazepines, ambien, sonata, lunesta
what is a schedule V medication?
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
what are the various routes of drug delivery?
- intramuscular
- IV
- subcutaneous
- inhalation
- topical
- oral
- rectal
what is first pass metabolism?
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
what is second pass metabolism?
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)
what are CYP450 enzymes?
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
what’s the difference between an active and a prodrug?
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
what substances induce the CYP1A2 system?
- tobacco smoking
- vegetables like broccoli, cabbage, brussel sprouts
- 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
what are the age related issues involved with the pharmacokinetics of medications?
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
what are the pediatric related issues involved with the pharmacokinetics of medications?
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
what are the STEPS of medication selection?
Safety
Tolerability
Efficacy
Payment
Simplicity
what is the time course of the efficacy of a medication?
different classes of psychotropic medications take different times demonstrate efficacy!!!
what is the time course to efficacy of antidepressants?
2 weeks for tolerability to get over the GI effects, etc.
4-6 weeks for 50% efficacy
12 weeks for full effects!!
what is the time course to efficacy of antipsychotics?
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!
what is the time course to efficacy of benzodiazepines?
almost immediate
can be used PRN for anxiety
what is SIGECAPS?
Sleep
Insomnia
Guilt
Energy
Concentration
Appetite
Psychomotor retardation
Suicidality
what comorbidities should you ask about before prescribing medications?
- SIGECAPS
- anxiety
- bipolar/manic
- psychotic = hallucinations, paranoia, delusions
- stressors = social, physical, work, home, medical
- substance use
- psychiatric
- medical review of systems
what is DIGFAST?
bipolar/manic symptoms
Distractibility
Irresponsibility
Grandiosity
Flight of ideas
Activity increases
Sleep deficit
Talkativeness
decreased appetite and racing thoughts too
which psychological illnesses require medications?
- psychotic disorders = YES
- bipolar disorders = mostly yes
- depressive disorders = maybe yes
- anxiety disorders = maybe yes
- 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
what medical evaluation should you do before prescribing a medication for a psychiatric illness?
- rule out toxicology reasons like drugs
- rule out other medical causes of psychiatric symptoms
- then consider psychiatric reasons
