Pharmacology

Pharmacology

The study of a drug or medication

Toxicology

Study of the adverse effects of chemical substances on living organisms

What was used as drugs for thousands of years?

Plants

Drug

A chemical or chemical compound used to diagnose, treat, or prevent disease

Nutraceutical

A food or fortified food substance that claims to treat or prevent disease but has NOT gone through rigorous government regulation (Ex. Dietary Supplements)

Toxicant

A material that is poisonous

Toxins

Produced by plants or animals

Contact

Touching skin

Ingestion

Eating

Inhalation

Breathing in

How do toxicants vary?

In their potency, which species/breeds are affected, and particularly in their lethal dose (Ex. Grapes: Dogs Vs. Hamsters)

Acute or chronic effects

Indications

Why drugs are being used

Contraindications

The reasons for not using drugs

Fever

An inflammatory response of the body

Pharmacokinetics

How a drug moves throughout the body

Pharmacodynamics

The action or effects of a drug on the body

Toxicity

How an adverse reaction can manifest itself

VCPR

Veterinary Client Patient Relationship

• Must know patient to administer medication

How often must you see a patient in NYS to refill meds?

Every 6 months

How often does the AVMA say you must see a patient to refill meds?

Every 12 months

ADME

• Absorption

• Distribution

• Metabolism

• Excretion

Chemical Name

Describes the chemical composition or the molecular structure of a drug

• Ex. D(-)-Amino-Hydroxybenxyl-Penicillin Trihydrate

Nonproprietary Name/Generic Name

The more concise name given to the specific chemical compound

• Ex. Amoxicillin

Proprietary Name/Trade Name/Brand Name

The unique name a manufacturer gives to its particular brand of drug

• Ex. Amoxi-Tabs

Once a company gets FDA approval to market a new drug,…?

That company has exclusive rights to that drug for 20 years from the approval of the patent

• Typically only 7-12 years for exclusivity after manufacturing

Generic Equivalent

Products of the same drug made by another manufacturer after its exclusive rights expire

Compounding

Any manipulation of a drug beyond that stipulated on the drug label

• Veterinarians are allowed to do this

Manipulation

Mixing, diluting, concentrating, flavoring, or changing a drug’s dosage form

Extralabel (Off Label)

The use of a drug that is not specifically listed on the FDA approved label

What conditions must be met for Extralabel use?

The veterinarian has sufficient knowledge of the animal and diagnosis, and the veterinarian must follow-up with the patient

OTC (Over The Counter)

Drugs that do not have enough potential to be toxic or that do not require administration in special ways/do not require the supervision of the veterinarian for administration

• Can be purchased WITHOUT a prescription

• Some are for veterinary use only

Solid Dosage Form

Tablets & Capsules

Liquid Dosage Form

Solutions, Suspensions, Tinctures, & Elixirs

Solutions

Drug completely dissolved in a clear liquid

Suspensions

Drug suspended in liquid, but not completely dissolved

Tinctures & Elixirs

Alcohol based solutions for oral and topical use (Holistic)

Semisolid Form

Gels, Paste, & Cream

Injectable Form

Administered by needle and syringe or via an implant under the skin

Reconstitute

Comes in powder and we have to turn into liquid

What is the fastest route of administration?

Intravenous

Role of the Veterinarian

Diagnose, Prescribe, Treat

By law, drugs CANNOT be handled, prescribed, or dispensed without…?

Written authorization from a licensed veterinarian

• Drugs may be handled, dispensed, and monitored by a vet tech under the supervision of a licensed veterinarian

Prescribing

Choosing which drug to give, in what form, and at what dose (Purview of the doctor)

Who has the responsibility of filling the prescription, including labelling?

The Vet Technologist

DEA

Drug Enforcement Administration/Agency

Other name for Controlled Drugs

Schedule Drugs

DEA preferred method to store controlled drugs for CIII-CV

A double-locked safe which is securely mounted to a permanent structure (Wall, Floor, Etc.)

• Access to keys must be LIMITED (Don’t store keys together)

DEA preferred method to store controlled drugs for CI & CII

Floor bolted 750lbs safe

Each controlled drug has their own…?

Logbook

Controlled Drugs

Those which have the potential to be abused by humans, with negative consequences

The lower the schedule number,…?

The higher the risk

Schedule 1 drugs theoretically have…?

No legitimate medical use

How does the DEA place drugs into their schedules?

Based on accepted medical use in the U.S.

Schedule I Drug Examples

Heroin, Cocaine, & Marijuana

Schedule II Drug Examples

Morphine, Hydromorphone, Pentobarbital, Fentanyl

Schedule III Drug Examples

Ketamine, Buprenorphine

Schedule IV Drug Examples

Alprazolam, Diazepam, Tramadol

Schedule V Drug Examples

Cough medicines with small amounts of Codeine, Diphenoxylate (Lomotil)

What controlled drug data must you keep track of?

ALL of it

• Name of patient, Name of drug, Amount drawn up, Amount used, Amount wasted (If any), Amount remaining in bottle/container, Your initials, Date/Time

• Info must reconcile at the end of a bottle or container

How must controlled drugs be disposed of in NYS?

By way of a reverse distributor (Drug Buster - Activated Charcoal)

When should inventory be taken for controlled drugs?

On a regular basis, and the amount on hand has to match the amount listed on the drug logs

How long does the DEA require all records of controlled substances to be maintained and available for inspection?

For a minimum of 2 years (NYS requires 5 years)

• Generally kept for 2 years on premise in NYS, 3 years kept elsewhere

Pharmacy

Preparing and dispensing medications

USP designation in the non-proprietary name stands for…?

United States Pharmacopeia

USP

Non-gov agency that sets standards for drug manufacturing quality and purity in the U.S.

• Provides assurance that drugs are manufactured to the standards required for drugs in the U.S.

Penicillin G (Pen-G)

• Narrow spectrum of activity

• High resistance

• Susceptible to Beta-lactamase

How is Penicillin G (Pen-G) given?

Injection ONLY - 3 types

1. Aqueous solution: Only IV

2. Suspension: SQ and IM only (IV is DEADLY)

3. Longer Acting: SQ and IM only (IV is DEADLY)

How long does Suspension Penicillin G (Pen-G) last?

24 hours

How long does Longer Acting Penicillin G (Pen-G) last?

3-5 days

Ampicillin & Amoxicillin

• Better activity against gram negative bacteria compared to Pen-G

• Susceptible to Beta-lactamase (Often combined with other drugs to bypass susceptibility)

How is Ampicillin & Amoxicillin given?

Available in injectable and oral formulations

Beta-Lactamase Resistant Penicillin

• Naturally resistant to beta-lactamase enzyme

• Do NOT work well against gram negative bacteria

What is Beta-Lactamase Resistant Penicillin mainly used for?

To treat Staph infections of the bone, skin, and mastitis

Examples of Beta-Lactamase Resistant

• Cloaxacillin

• Dicloxacillin

• Oxacillin

• Methicillin

Extended Spectrum Penicillin

Cephalosporin

• Have a beta lactam ring

• Work by disrupting cell wall formation

• Susceptible to beta-lactamase

• BEGIN with “cef-“ or “ceph-“

• Categorized by generations

What does Cephalosporin work well against?

• Streptoccoucs sp. & Staphylococcous sp.

• Good for treating bacterial infections of the urinary tract

Caphalosporin 1st Generation

Good against gram +

Cephalosporin 2nd Generation

More effective against gram negative bacteria, less effective than gram positive cocci

Cephalosporin 3rd Generation

Good against gram -, Some effectiveness against gram +

Action of Cephalosporin

Bactericidal

• Same mode of action as Penicillin

Cephalosporin Pharmacokinetics

• Does NOT cross the blood brain barrier (Not good to treat infections of CNS)

• WILL cross the placenta and affect fetal tissues as well as milk supply of nursing females

• Has high concentrations in the urine of animals

Cephalosporin Precautions

• Hypersensitivity reactions similar to Penicillin

• Oral administration can commonly cause anorexia, vomiting, & diarrhea

Cephalosporin Hypersensitivity

• If seen with one generation, will most likely occur with another generation

• Animals tend to have less reactions to Cephalosporins than they do to Penicillin

Cephalosporin Examples

Aminoglycosides

• Bactericidal

• Good against gram negative -, aerobic bacteria

• End in “-micin” or “-mycin”

Aminoglycosides Examples

• Gentamicin**

• Amikacin**

• Neomycin

• Tobramycin

• Kanamycin

• Apramycin

• (** = Most Commonly Used)

Aminoglycosides Mode of Action

Combine with ribosomes and prevent synthesis of proteins from amino acids in the bacterial cell

• Require oxygen for active transport into the cell (This is why it is only effective against aerobic bacteria)

• Work even better if cell wall of bacteria cell has been degraded (By Penicillin or Cephalosporin)

What are Aminoglycosides dependent on?

Concentration dependent drugs

• Peak concentration occurs rapidly and falls rapidly

• However, residual effect is long lasting

Aminoglycosides Pharmacokinetics

• Hydrophilic

• Need to reach high concentration levels quickly

• Does NOT penetrate blood brain barrier & globe of the eye

• Can reach the respiratory tract if aerosolized

How are Aminoglycosides given?

Best routes of administration: SQ, IM, IV

• Only a few are given PO

• Readily absorbed through damaged skin, so soaked bandages on de-gloving wounds

Aminoglycosides Precautions

Can be ototoxic & nephrotoxic

• Actively pumped into these areas

• Cats are sensitive to ototoxicity

• See casts and increased protein in urine during Nephrotoxicity

Use caution in animals with decreased kidney function

• Kidneys are main route of elimination

Action is negated by pus and cellular debris

• If using on an open wound, clean first

Fluroquinolones

• AKA quinolones

• Bactericidal

• Effective against gram + AND gram - aerobic bacteria

• End with “-floxacin”

Fluroquinolones Examples

**No Fluroquinolones approved for equine use - Off label use only!!**

• Enrofloxacin (Baytril): Dogs & Cats

• Marbofloxacin (Zenequin): Dogs & Cats

• Orbifloxacin (Orbax): Dogs & Cats

• Difloxacin (Dicural): Dogs ONLY

• Pradofloxacin (Veraflox): Cats ONLY

• Danofloxacin (Advocin): Beef Cattle ONLY

Fluoroquinolone Mode of Action

Interferes with the coiling of DNA, leading to cell death

• Covers many bacteria that beta-lactam drugs (Penicillin & Cephalosporin) do not cover such as: Klebsiella, E. Coli, Salmonella, & Staphylococcus (gram +, Beta-lactmase)

• NOT effective against Streptococcus sp.

• Concentration dependent - MUST reach high concentrations quickly - Good residual effect

What is Fluoroquinolone commonly used for?

• Urinary infections

• Skin infections (Good at treating bacterial skin infections in reptiles (Pseudomonas & Salmonella))

• Prostate infections

Tetracycline

• Bacteriostatic

• Do NOT work against anaerobic bacteria

• End in “-cycline”

What 2 categories is Tetracycline divided into?

• Old = Hydrophilic (Ex. Tetracycline, Oxytetracycline)

• New = Lipophilic (Ex. Doxycycline, Minocycline)

Which category of Tetracycline is more commonly used in vet med today?

New (Lipophilic)

• Have a longer half life

• Better spectrum of activity

• Better tissue penetration

• Good at finding “invaders” in mammalian cells (intracellular pathogens)

What should Doxycycline always be given with in cats?

Water after being given the drug to prevent esophageal stricture