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PSYCH 478 > Topic 1: Pharmacology and Pharmacokinetics > Flashcards

Topic 1: Pharmacology and Pharmacokinetics Flashcards

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1
Q

What is neuro-psychopharmacology?

A

the study of the actions of drugs on the central nervous system and their subsequent effects on human behavior

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2
Q

What are drug actions?

A

specific molecular changes resulting from drug binding to a target site or receptor

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3
Q

What are drug effects?

A

widespread alterations in physiology or psychology resulting from drug actions

what the drug does to behavior

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4
Q

What is therapeutic effects?

A

drug-target interactions producing the desired physiological or behavioral changes

what the goal of the drug is

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5
Q

What are side effects?

A

all other drug effects

any other effect that is not the goal

means you can use some drugs for different therapeutic effect

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6
Q

What are adverse effects?

A

undesirable or harmful drug effects

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7
Q

What are specific effects?

A

occur as a result of biochemical interactions between drug and target receptor

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8
Q

What are nonspecific effects?

A

occur as a result of interactions beyond the receptor (e.g., lipid membranes, fluid compartments)

may occur as a result of unique characteristics of an individual or an individual’s state

not the drug binding directly caused by chain reaction secondary effects

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9
Q

What is a placebo effect?

A

measurable therapeutic effect of a treatment without specific activity for the respective condition

affected by expectancy and conditioning

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10
Q

In what way is the placebo effect a confound in neuropsychopharmacology?

A

antidepressants have efficacy of ~50-70% in major depression

placebo is effective in 20-30% of cases

during development fluoxetine (Prozac) had to endure 5 clinical trials to achieve 2 showing significantly better response than placebo

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11
Q

What is the classic experiment on ulcer patients given placebo?

A

group A given placebo by physician who assured the medication would give relief (efficacy of 70%)

group B given placebo by nurse who described it as experimental in nature (efficacy of 25%)

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12
Q

What is pharmacokinetics?

A

the dynamic factors contributing to the bioavailability and efficacy of drugs in the human body

provides performance guidelines for efficacy and efficiency of drug use in clinical settings

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13
Q

What are the principal of pharmacokinetics?

A

absorption: administration and absorption of the drug into body fluids

distribution: dispersal of drug through body fluids to the target tissues of the body; depot binding in bodily fluids and non-target tissues

metabolism: biotransformation or inactivation of drugs in the body into metabolites

excretion: removal of substances or metabolites from the body

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14
Q

What are the routes of administration?

A

oral administration
intravenous
intramuscular
subcutaneous
inhalation
topical
sublingual (below the tongue)
transdermal (e.g. nicotine patch)

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15
Q

What routes of administration are only used in experimental studies?

A

intraperitoneal (IP)
intracranial
intracerebroventricular
intracisternal

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16
Q

What is oral administration?

A

most convenient

safe self administration

first-pass effect

blood-brain barrier (BBB) affects usefulness for neuropharmacology

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17
Q

What is the first-pass effect?

A

blood flow from stomach/intestines goes directly to the liver for detox

oral route has greatest breakdown of drug

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18
Q

What is delivery to cerebral spinal fluid?

A

epidural, intracranial, intracerebroventricular or intracisternal most direct way to access the CNS

bypasses liver and BBB

highly invasive

effectively for experimental use only

slow steady release possible with implantable shunts or osmotic minipump

19
Q

What is drug absorption?

A

movement of drug from the site of administration to the circulatory system

largely dependent on passive diffusion through biological membranes

20
Q

What is drug absorption affected by?

A

drug concentration: affected by age, sex, body, size, body fat content

breakdown by metabolic or digestive processes

solubility and ionization of drug

21
Q

What are polar molecules?

A

water soluble

hydrophilic (loves water)

lipophobic (fears fat)

polar molecules are freely transported through aqueous compartments (e.g., blood, CSF, ECF)

22
Q

What are non-polar molecules?

A

lipid soluble

hydrophobic (fears water)

lipophilic (loves fat)

non-polar molecules freely diffuse across semi-permeable membranes (e.g., intestinal wall, BBB, cell membranes)

23
Q

How is absorption dependent on drug polarity?

A

non-polar, lipid soluble drugs can freely diffuse across cell membranes

passive diffusion down concentration gradients

non-polar molecules ted to be less soluble in water

polar or charged (ionized) drugs are prevented from diffusing through membranes

many orally administered drugs are weak acids or bases - gaining or losing charges based on the pH of the external environment

24
Q

What are the factors affecting drug absorption?

A

intrinsic properties of the drug: polarity, solubility, pKa

pH of body compartments

surface area of body compartments: stomach has a relatively small surface are (slow absorption), intestine have relatively large surface area (fast absorption) and are the site of most (oral) drug absorption

25
Q

What is drug distibution?

A

once in the bloodstream drugs circulate to the entire body within minutes

drug concentration is highest in tissues with greatest blood flow (heart, brain, kidney, liver)

peripheral capillaries are highly porous allowing ready distribution of drugs (lipophilic or hydrophilic) into tissues

blood-brain barrier permits passive diffusion of only lipophilic drugs

26
Q

What is the blood brain barrier?

A

peripheral capillaries are porous, allowing hydrophilic drugs to freely enter tissues

brain capillaries are coupled by tight junctions and lined by astrocyte endfeet creating a highly impermeable barrier

27
Q

How do drugs cross the blood brain barrier?

A

the blood brain barrier limits access to 98% of small molecule pharmaceuticals (and 100% of large molecule pharmaceuticals)

passage of solutes through the BBB often occurs at specific transporters (e.g. glucose and amino acid transporters)

some drugs are actively removed from the ECF by efflux transporters (i.e. p-glycoprotein, a.k.a.multidrug resistance protein-I)

28
Q

What are the permeable sites of the blood brain barrier?

A

chemoreceptor trigger zone

hypothalamus

29
Q

What is the chemoreceptor trigger zone (CTZ)?

A

of the medulla (area postrema - vomit centre)

allows direct detection of toxins in the blood

30
Q

What is the hypothalamus?

A

allows direct access to capillaries for secretion of neurohormones and hormone-releasing factors

31
Q

What is the placental barrier?

A

the placenta creates a similar selective barrier (unique to pregnant mammals)

drugs (licit and illicit), alcohol, gaseous anesthetics, and gases (e.g. carbon monoxide) readily cross the placental barrier and can cause acute toxicity or teratogenic effects to the fetus

32
Q

What is depot binding?

A

drug depots are inactive drug binding sites with no measurable biological effect: adipose tissue (lipid-soluble drugs), muscle tissue, albumin (plasma protein)

decreases circulating drug concentration

prolongs drug action: can function s reservoirs for drug release, protects stored drug from metabolism

can explain individual differences in drug efficacy

33
Q

What is drug metabolism?

A

biotransformation and elimination affects bioavailability

metabolism occurs primarily in the liver under control of microsomal enzymes

cytochrome P450 family (CYP - 57 in total) oxidize the majority of psychoactive drugs

metabolism is a non-specific detoxification process that occurs in two distinct types or phases

34
Q

What is type I metabolism?

A

non-synthetic modifications

oxidation, reduction, and hydrolysis

35
Q

What is type II metabolism?

A

synthetic modifications

conjugation with glucuronide, sulfate, or methyl groups

36
Q

What is biotransformation?

A

type I metabolism during first pass can produce active metabolites of the pharmaceutical preparation of drugs

metabolic products (active and inactive) are returned to circulation from the liver and can reach target sites of action or sites for excretion (kidneys, biliary, or facial excretion)

37
Q

What is simvastatin (Zocor)?

A

pharmaceutical preparation is the lactone form - hydrophobic

simvastatin is hydrolyzed in the liver to the bioactive acid form

38
Q

What are the factors influencing metabolism?

A

enzyme induction

enzyme inhibition

drug competition

individual differences

39
Q

How does enzyme induction influence metabolism?

A

repeated use results in increase in liver enzymes

accelerates rate of biotransformation of all drugs metabolized by a given enzyme (contributes to tolerance and cross tolerance)

40
Q

How does enzyme inhibition influence metabolism?

A

drugs targeting enzymes (e.g. monoamine oxidase inhibitors - MAOI) decrease their own clearance and other drugs

41
Q

How does drug competition influence metabolism?

A

competition for enzymes may prevent some drugs being metabolized in a safe fashion

42
Q

How do individual differences influence metabolism?

A

genetic polymorphisms have been identified in metabolic enzymes

different individuals have different rates of clearance for drugs

43
Q

What is drug excretion?

A

routes of excretion include breath, sweat, saliva, feces, breast milk and urine

primary means is filtration by kidney and excretion through urine

most drugs are excreted by first-order kinetics: exponential elimination - constant fraction removed in a given time

very few drugs removed by zero-order kinetics (constant rate)

PSYCH 478 (28 decks)

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