PHAR 266: LO1- Explain how Pharmacology Impacts DH Care

chemical name

-used during research and development stages

-describes the chemical structure

-example: 2-(p-isobutylphenyl) propionic acid

generic name

-generic drug name (any pharmaceutical company can use)

-example: ibuprofen

trade name

-registered trademark (brand name)

-only the pharmaceutical company which develops the product may use it

-capitalized

-example: Advil

generic pharmaceutical companies

-has a patent and will be the only company which can produce the product

-one patent expires, other companies may manufacture generic products

-contain same active ingredients but may contain different excipients

-company prefix goes in front of generic drug name

-example: Apo-Furosemide, Ava-Ramipril

are genetics certified as equivalent to trade products

yes

genetic vs trade name (innovator): what is the same?

-active ingredients

-same dose of active ingredients

-same absorption rate

-same mechanism of action

-both approved by Health Canada for safety, quality and effectiveness

genetic vs trade name (innovator): what is different?

-excipients

-colour, shapes, markings

-price

what are the contents of tablets

-active ingredients

-excipients (inactive ingredients) but may cause adverse effects

-preservatives

inactive ingredient: fillers/diluents

-add vol to make tablet a manageable size

inactive ingredient: binders

-hold ingredients together in a shape

inactive ingredient: disintegrants

-assist in breaking tablet down in digestive tract

inactive ingredient: lubricants

-prevent ingredients from sticking to machinery during production

inactive ingredient: coating

-to improve taste, appearance, ease of swallowing

inactive ingredient: colorant/flavours

-for identification and taste

potency

-amount of drug needed to produce an effect

-example: morphine is more potent than oxycodone, hydromorphone and codeine

efficacy

-max effect or response that can be produced by a drug

-example: morphine is efficacious for severe pain while acetaminophen is not

mechanism of action

-drugs bind to receptors on the cell

mechanism of action: agonist

-drug binds to receptors to cause a response (enhance cell function)

mechanism of action: antagonist

-drug binds to receptors but does not elicit a response (inhibits cell function)

dose equation

-dose=amount x frequency

plasma level

-amount of drug present in blood stream

-increases as drug absorbed into blood stream

-decreases as drug is metabolized and excreted

-must be therapeutic level present for drug to exert systemic effect

when does plasma level increase?

-as drug is absorbed into the blood stream

when does plasma level decrease?

-as drug is metabolized and excreted

therapeutic index

-ration of medial lethal dose to the median effective dose

what is median lethal dose

-dose that is lethal in 50% of test animals

what is median effective dose

-dose that produces desired effect in 50% of test animals

drugs with a high therapeutic index are

-safer (bigger difference bw therapeutic dose and lethal dose)

drugs with a low therapeutic index must be

-carefully monitored for toxicity bc there is not much difference bw the therapeutic dose and lethal dose

which drug for heat failure has a low therapeutic index?

-Digoxin

how is therapeutic drug level monitored

-some drugs require therapeutic drug level blood tests to ensure plasma level of drug within range

-example: some anticonvulsants, mood stabilizers, anti-psychotics, digoxin

pharmacokinetics

-movements of drug into, through, and out of the body

pharmacodynamics

-biochemical and physiological effects of a drug

most common route of administration

-oral route

oral route

-local (antacids)

-systemic (antibiotic)

-dosage forms such as capsules or tablets must be digested before they can be absorbed

rectal route

-inserted into rectum

-if cant use oral route (can't swallow or if vomiting)

-local effect (hemorrhoid suppository)

-systemic effect (analgesic)

topical route

-applied to a surface (skin or mucosa)

-local (topical anesthetic)

-systemic (nitroglycerin)

sublingual route

-applied to mucosa under tongue

-systemic (nitroglycerin)

transdermal route

-applied to skin via patch

-local (local anesthetic patch prior to starting IV

-systemic (nitroglycerin, morphine, estrogen)

inhalation route

-inhaled into lungs

-local (bronchodilator-salbutamol rescue inhaler)

-systemic (halothane-anesthetic)

intravenous route

-injected into vein

-systemic (midazolam)

intramuscular route

-injected into a muscle

-systemic (Epi pen)

subcutaneous route

-injected under skin

-systemic (insulin)

intra-articular route

-injected into a joint

-local effect (steroid)

subgingival route

-gel placed into sulcus

-used for topical anesthesia

-Cetacaine or Oraqix

absorption

-absorbed from site of administration into blood stream

absorption: local effect

-drug effect ends when absorbed into blood stream

absorption: systemic effect

-drug effect begins after absorbed into blood stream and carried to site of action

absorption: if injected into blood stream

-no absorption

what might absorption from oral route be impacted by

-other drugs and food (some drugs must be taken on an empty stomach before or after meals)

distribution

-drug is transported via blood stream and delivered to other parts of body

distribution: free form

-biologically active drug

distribution: bound to plasma proteins

-inactive

-considered a storage form

distribution: what may lead to drug interactions and toxicity?

-drugs may completely bind with plasma proteins

redistribution

-movement of a drug from one site to another

-drug will bind receptors at specific site and cause pharmacological effect

redistribution: movement away from specific site will cause

-drug action to stop

what does redistribution affect?

-duration of action

first pass effect

1. drugs given by the oral route are absorbed through the small intestine wall then travel directly to liver

2. in liver, some of the drug undergoes biotransformation

3. remainder of drug enters the systemic circulation

bioavailability

-amount of drug which enters the systemic circulation and is available to produce a systemic effect

do drugs given by IV route undergo a "first pass" effect?

-no

drugs with a high "pass effect: will have

-a much higher dose compared to the IV dose

biotransformation

-drug is changed into other chemical compounds

what are metabolic products called

-metabolites

what does biotransformation allow?

-drug to be eliminated from body

where does biotransformation usually occur?

-in the liver

are metabolites active or inactive?

-they can be both

cytochrome enzyme system: CYP 450

-enzyme system that metabolizes many drugs (substrates)

what is CYP 450 induced by?

-some drugs

-lower plasma level of substrate which decreases activity

what is CYP 450 inhibited by?

-other drugs

-higher plasma level of substrate

what does CYP 450 cause?

-drug interactions

-may impact duration of action, risk of toxicity and efficacy

excretion

-drug is eliminated from body

-usually in kidneys through urine

-also by saliva, bile, breast milk and sweat

elimination half life

-time it takes for half of drug to be eliminated from body

drugs with a long half-life are cleared slowly or quickly

-slowly

most drugs follow what

-first order kinetics

what is first order kinetics

-constant fraction of drug eliminated per unit time

-time it takes for half of the drug to be metabolized and excreted (t1/2)

-1st half life= 50% of drug

-2nd half life= 75% of drug

drugs are considered to be eliminated after how many half lives?

-4 or 5

zero order kinetics (aspirin and alcohol)

-for drugs whose metabolism is saturable

-with small dose (drug metabolized faster)

-with larger dose (metabolism cannot increase and takes longer for a larger dose to be eliminated)

which factors alter a drug's effects?

-compliance

-psychological factors

-tolerance

-disease

-time of administration

-route of administration

-sex

-genetics

-drug interactions

-age & weight

drugs: age related effects

-decrease in function of organs as ppl age

-decreased ability to absorb, distribute, biotransform, and excrete drugs

-makes older adults more susceptible to adverse effects

placenta

-most drugs pass easily across the placenta

-drugs given to the mother are also administered to the fetus

teratogens

-some drugs have potential to harm the developing embryo/fetus

-some may be used with caution

-some are contraindicated during pregnancy

-many dental drugs (LA, some antibiotics and some analgetics) are safe during pregnancy

guidelines during pregnancy

-only prescribe/administer if necessary

-consider risk to developing embryo/fetus

-avoid elective DH care during 1st trimester and end of 3rd

concerns during pregnancy

-teratogenesis (highest risk during 1st trimester)

-affects on near-term fetus leading to adverse effect in newborn (respiratory depression & jaundice)

-long-term psychological & physiological effects (may not be evident at birth)

CPS (Compendium of Pharmaceuticals and Specialties): product monographs contain recommendations for

-people of child-bearing potential

-contraceptive measures

-preg people

-lactating people

best practices for using dental drugs during pregnancy & lactation

-use only if required

-confirm in drug reference before using/recommending

which anesthetic is best choice during all trimesters?

-lidocaine & limit E to 0.04mg

which pain killer is best choice during all trimesters?

-actetaminophen

which antibiotics are best choice during all trimesters?

-amoxicillin

-penicillin V

-azithromycin

which anti-fungal is best choice during all trimesters?

-nyastin anti-fungal

dental drugs during pregnancy & lactation: nitrous oxide

-contraindicated in 1st trimester but ok in 2nd and 3rd

dental drugs during pregnancy & lactation: anti-virals & most anti-anxieties

-contraindicated in all trimesters

drug actions can cause

-desired effect

-adverse reaction

side effect

-most common type of adverse reaction

-most drugs have side effects

-undesired effect that happens when a drug is administered

most common types of side effects

-GI upset

-xerostomia

hypersensitivity

-allergies

-exaggerated immune response against foreign substance

-may be immediate or delayed

-may be localized or systemic

-skin, respiratory or anaphylactic

what are the types of hypersensitivity?

-type I

-type II

-type III

-type IV

type I: immediate anaphylactic reaction

-IgE antibodies trigger release of histamine from mast cells and basophils

-onset within mins of exposure

-examples: drug allergies, anaphylaxis, hayfever, food allergies

type II: cytotoxic reaction

-IgG or IgM antibodies bind to antigens on cell surface and cause complement mediated cell lysis

-onset is hours to days after exposure

-examples: transfusion, Rh reactions and autoimmune hemolytic anemia

type III: immune complex reaction

-antigen-antibody complexes are deposited in tissues which activates complement, attracts polymorphonuclear cells and causes tissue damage

-onset is 2-3 weeks after exposure

-examples: rheumatoid arthritis and systemic lupus erythematosus

type IV hypersensitivity reactions

-delayed reaction

-cell mediated by helper T lymphocytes

-onset is 2-3 days after exposure

-examples: contact dermatitis, poison ivy, TB tests

dose

-amount administered and frequency