pharmacology general principals part 1

Pharmacology

The study of how drugs and chemicals work (natural and synthetic) and the changes produced by these drugs in living organisms.

Drug

Any chemical substance capable of modifying a biological activity in the body.

what do we use drugs for?

• prevention

• treatment

• anesthesia

• pain control

• diagnostics

how do we classify drugs? (4)

1. effect

   • bacteriostatic drugs

   • diuretics

   • stimulants

2. structure

   • steroids

   • barbiturates

   • glycosides

3. action

   a) physical terms - relates to the type of drug activity

   b) physiological terms - relates to the drugs effect on the function of a particular body part

4. source

   • inorganic - derived from non living sources and do not contain carbon

   • organic - derived from living organisms and contain carbon

   • synthetic - produced artificially by chemical or biochemical means

what can inorganic drugs be further classified into?

whether the pharmacological effect is produced by the catonic charge (+ charge) or anionic charge (- charge) part of the drug

6 steps to ensure patient safety

1. correct drug

2. correct dose

3. correct time

4. correct route and technique

5. correct patient

6. correct documentation

forms of medication

• liquids

  • ex. suspension, emulsion, solution, liniment

• solids

  • ex. tablet, chewable, capsule, bolus, powders, suppositories, implants

• gases

  • ex. liquids vaporized, medications nebulized, oxygen

• topical medications

  • ex. ointments, creams, gels, patches, paste, lotion, liniment

routes of administration are affected by…

• formulations available

• patient temperament and condition

• convenience

• cost

• pharmacokinetics

onset of action

• from administration to target

• once it is in the patient, how long until it starts working

• influences the ROA

• generally fastest to slowest =

  IV, IM, SQ, rectal, inhalation, PO, transdermal

duration of action

• how long the drug remains effective in the body

• the shorter the onset of action the shorter the duration of action

topical

• on the skin, usually for a localized effect

• a transdermal patch for long steady systemic absorption

• may need to wear gloves because you could absorb an undesirable drug

parenteral

• drugs given by routes other than the digestive tract

• avoiding absorption by both the stomach and intestines

• to obtain rapid changes of the drug in blood levels

• most commonly uses a needle and syringe

• IV, IM, and SQ most common

common injection types

• IM - intra muscular

• IV - intra venous

• SQ - under the skin

• ID - between the skin layers

IV

• used for emergency drugs

• drug is too irritating by other routes

• precise dose

• long term administration for short acting drugs

• fastest onset of action, shortest duration

• IV catheter

• fluid lines

• vessels

• aspirate first

IM

• if SQ is too slow

• drugs in suspension (cannot give IV)

• fractious animals (cannot access IV)

• reasonably fast onset, fair duration

• use as big a muscle as possible (to help with soreness)

• aspirate

SQ

• if slower, prolonged absorption is preferred

• slower onset of action, longer duration than IM and IV

• avoids irritating vessels

• can give larger volumes than IM

• under the skin, “tent”

• most common for vaccines

• aspirate

IP

• intra peritoneal

• when other routes are unavailable (pocket pets)

• in food producing animals to administer larger volumes when there’s no IV access

• fairly rapid absorption and onset, short duration

• absorption via the liver

• risk of organ laceration

IA

• intra articular

• diagnostic testing

• local anesthesia

• VERY STERILE

• infusions directly into the joint cavity

IO

• intra osseous / medullary

• neonates, exotics, avian

• emergencies when IV access is difficult

• fast onset, short duration

• aseptic

• fluid administration

• proximal condyle of humerus or femur

IC

• intra cardiac

• not routine route

• emergency or euthanasia

• anesthetized or unconscious patients only

IT

• intra tracheal

• cardiac stimulant drugs

• during CPCR if venous access not yet attained

• via the endotracheal tube (need 2x the amount because its going right to the lungs)

• rapid onset and absorption (short duration)

epidural

• spinal anesthesia

• anesthetic agent injected into the epidural space

• small animals must be anesthetized

• aseptic technique

• 10-15 min onset, duration depends on the drug (average several hours)

ID

• intra dermal

• allergy testing and diagnostic testing

• in the skin layers

• small gauge needle

PO (oral)

• easiest for owners

• when longer duration of action is needed

• directly or indirectly into the GI tract

  • ex. hand pill, syringe, OG or NG tube

• GIT must be functional

• onset of action slow because it must cross more barriers (cell membrane of the stomach)

• larger dose is required than parenteral routes

  • not all the drug is absorbed from the GIT because it gets diluted by fluids along the way

  • the drug passes through the liver where some of it is metabolized before reaching the site of action (first pass effect)

  • vomiting and diarrhea reduce the effectiveness

inhalation

• to deliver gas, vapor, or aerosol

• O2 can be the vehicle

• mask, induction chamber, endotracheal tube, inhaler

• rapid absorption due to the large surface area of the alveoli and high concentration of blood vessels

• rapid excretion

legal considerations (2 levels)

pharmaceuticals are controlled at 2 levels in Canada

1. federal - the food and drugs act

2. provincial - the drug and pharmaceuticals regulation act

federal level

• legislation governing the approval of drugs

• labelling / package requirements

• DIN (drug identification number)

• VDD (veterinary drug directorate)

provincial level

• deals with the sales of pharmaceuticals

• classifies drugs

D classificaton

biologics

• ex. vaccines

G classification

controlled drugs

• ex. street drugs, can change at any time

N classification

narcotics

• ex. make you sleep, all narcotics are controlled drugs but not all controlled drugs are narcotics

F part 1 classification

prescription drugs

F part 2 classification

veterinary drugs

• G and N drugs must be double locked and logged

DIN

• drug identification number

• 8 digit number assigned by health Canada

• product characteristics that identify a product as unique

  • manufacturer

  • product name

  • active ingredients

  • strength of active ingredient

  • pharmaceutical form

  • route of administration

  • class (human vs. veterinary)

drug name: chemical

• describes the chemical composition

drug name: generic

• common name chosen by the developing drug company, then becomes the standard name

• listed after the trade name and is not capitalized

• not protected property of the drug company and may be used by competitors

drug name: trade / brand

• given by the company who patented, developed, and tested the drug before bringing it to the market

• known as both the owner name and brand name

• first name on a drug label, bolded, capitalized

• 20 year original patent, then drugs may have several trade names

prescription label must haves

1. name, address, and number of the clinic

2. name of the prescribing vet and their license #

3. name and strength of the drug

4. volume or number of drug dispensed

5. date dispensed

6. expiry date (if applicable)

7. clients name

8. animals name or #

9. directions for use

10. any warnings or health hazards

11. drugs withdrawal time (if applicable, for livestock or food animals)

12. whether it’s refillable, if so, how often

compounded veterinary drugs

drugs that have been changed from one form to another form, could be for concentration, ease of administration, flavoring, pill to liquid, etc.

• compound products from active agents

• for one time use and one client only

• may not be resold to other clients

• only time there is no DIN #

• super expensive

• short dated (3 months or 90 days max)