Pharmacology

Pharmacology

The science of how drugs act on biological systems and how the body responds to the drug

Toxicology

The measurement and analysis of potential toxins, intoxicating or banned substances, and the prescription medications present in a person’s body.

Pharmacotherapeutics

The clinical purpose or indication for giving a drug, what is the benefit we are trying to get

Pharmacokinetics

Describes the movement of drugs within the body, where it goes in and out

Pharacodynamics

Describes the effects the drugs and mechanism of their action. The process of things going on. Drug meets receptor, we get a response.

Chemical name of drug

Describes the chemical composition of the medication

Generic name

Generally derived from the chemical name or a primary component of the chemical, follows specific nomenclature

Brand name

a name used for marketing specific to a manufacturer

True or false? Generic drugs are not commercially available until the protective patent for the Brand drug has expired

True!!!

Generic medications are said to be bioequivalent if…

-Type and amount of active ingredient

-same administration route

-same pharmacokinetic profile (absorption, distribution, elimination)

-found to have same therapeutic effects (some generics aren’t the same)

Preclinical testing

Initial laboratory tests to determine drug effects and safety. Subjects are lab animals, takes 1-2 years

Phase 1 testing

Determine effects, safe dosage, pharm kinetics. Is it okay? Is it healthy on volunteers? Less then 100 people, less then a year

Phase 2

Assess drug’s effectiveness in treating a specific disease/disorder, limited number of patients (200-300) with target disorder. 2 years.

Phase 3

Assess safety and effectiveness in a larger patient population. Large number of patients, 1000-3000 targeted, 3 years

Phase 4

Monitor any problems that occur after NDA approval. General patient population, indefinite

Prescription

Medication can only be dispensed to patients with prescriptions from a qualified APP by a qualified pharmacist

Over-the-counter

Medication that does not require a prescription to be purchased/dispensed

Off-label processing

Prescription of a drug for a purpose other than the purpose specifically approved by the FDA. Strong evidence it works, but haven’t gone through the 7-10 year process yet

Dose-response relationship: threshold dose

The minimum dose of drug that triggers minimal detectable biological effect. Until you take a certain dose there’s not going to be a therapeutic effect.

Dose-response relationship: Ceiling effect

Point at which a drug’s impact on the body plateaus. Ex: taking a bunch of antibiotic pills isn’t going to be more helpful than one

Potency

The measure of a drug’s biological activity expressed in terms of the dose required to produce an effect of a given intensity. More potent= more of a response

Efficacy

The maximum effect that a drug can produce regardless of dose

Quantal Dose-Response Curve

Reports the response of an entire sample group of patients/subjects

Median Effective Dose

Dose that produced a specific beneficial therapeutic response in 50% of the population

Median toxic dose

Dose that produced a specific toxic response in 50% of the population

Therapeutic Index

a function of safety of the medication assessed. TI=TD/ED

Agonist receptors

-direct—> ion channel opening/closing

-transduction—> enzyme activation, ion channel modulation, DNA transcription.

Antagonist receptors

no effect, just blocks the receptors!

Ion channels: blockers

Permeation, blocks ion from coming in

Ion channels: Modulators

Increased or decreased opening probability. Ex: antipsychotic meds

Pharmacokinetics: Absorption

How will it get in?

Pharmacokinetics: Distribution

Where does it go?

Pharmacokinetics: Metabolism

How it’s broken down

Pharmacokinetics: Excretion

Where it goes

Enteral absorption

Alimentary canal, goes from mouth to butt. Includes oral, lingual, buccal, rectal

Oral absorption

pills, tablets, and suspensions

Lingual, sublingual absorption

Under the tongue. Ex: nitroglycerin

Buccal absorption

in the cheek. Ex: Fentanyl Buccal

Rectal absorption

Suppositories, butt

Parenteral absorption

Everything else, not enteral. Includes injection, inhalation, topical, transdermal.

Parenteral: injection

IM, IV, Intrathecal (space in spinal cord, such as nerve block). SQ (under skin)

Parenteral: inhalation

Advair, Qvar Nebulizers

Parenteral: Topical

Absorbed right through skin. Ex: Hydrocortisone

Parenteral: Transdermal

drugs delivered into the bloodstreams. Ex: Lidocaine patches

Bioavailability

The proportion of a drug or other substance which reaches systemic circulation when introduced into the body. How much is getting to circulate, bioavailability is generally higher in medications absorbed parenterally. When a drug becomes completely available to its intended biological destinations.

First Pass Effect

Medications that are absorbed in the GI tract are processed by the liver before entering general circulation. **Some drugs are inappropriate for oral admin

The ability of the drug to cross membranes and barriers is related to

-administration route

-Physiochemical properties of the drug

-drug’s interaction with plasma proteins and other potential “carriers”

-Protein and/or water solubility

-Natures of the various “barriers” in the body

Volume of Distribution

Ratio of (amount of drug administered) and (concentration of drug in plasma). Used to determine if the medication is being retained in plasma, tissue, or evenly distributed throughout body.

Drug “storage”

Medications, especially lipid soluble medications, may accumulate in tissue such as fat, muscle, bone, liver, kidneys. Local tissue damage—> concentration of drug may damage local tissue. Redistribution—> drug stored in fat may then be re-released when the fat tissue is broken down and may have an effect that is no longer desirable or therapeutic.

Metabolism

The breaking down of drug from an active form to an inactive or less active form or byproduct

Primary sites of metabolism

75% of metabolism is performed in the liver, other sites include lungs, kidneys, GI tract, and skin

Metabolite

the inactive or less active byproduct, after we breakdown into something else, can be toxic!

Active Metabolites

Some metabolites may continue to affect the body and continue to have the active drug’s effects and side effects

Phases of Metabolism

Phase 1: Oxidation, Reduction, Hydrolysis

Phase 2: Conjugation—> add to another molecule or protein

Where does the majority of excretion occur?

The kidneys! Other significant sites include lungs and GI tract. Majority of excretion in kidneys occurs after metabolism in the liver! —> works it’s way out of system via diffusion

Drug Clearance

The rate at which the active drug is removed from the body.

What 2 features is clearance dependent on?

Blood flow to the organ, extraction ratio (the organ’s ability to remove the drug).

True or false? Disease processes or impairments that reduce Q and/or E will impair an organ’s ability to clear drugs.

True!!

True or false? Decreased clearance will not prolong medications effects and side effects.

false! they may prolong

Half-life

How long med stays in the system, describes the amount of time required for 50% of the active form of the drug to eliminated.

Dosing schedules

Medications administered continuously will have more consistent and stable levels of drugs in the blood stream. Extended release drugs stabilize drugs levels and availability.

Factors affecting Normal Pharmacokinetics

-disease

-age

-genetics

-gender

-body composition

-diet

-other chemicals

-physical factors

Drug effects on rehab

-coordinating rehab services with drug peaks and troughs

-rehab services have an opportunity to identify and recognize improper drug responses

-Therapy environment may affect absorption/distribution