Pharmacology – Intro

Drug
any substance, other than food, which alters physiologic function, regardless of whether the effect is beneficial or harmful

Chemical name
A name based on the chemical structure of the compount, name is long and is not often used by HC or public

Ex/ 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-aaas=dfasdfa.. etc

Generic Name
A name considered the official name of the compound

ex/ sildenafil citrate (what we will use)

Brand name
A name given to the drug by teh pharmaceutical company, compyrighted to that company.

– once the patent expires, others companies have the right to market the drug and even assign their own brand name, ^not effective to clinically use this name.

Drug classification
Drugs are often classified into categories, but there’s not a universally

ex/ antivirals, antibiotics, antihypertensives

can be useful for studying pharmacology

pharmacotherapeutics
a main area of pharmacology, includes pharmakinetics and pharmacodynamics

pharmacokinetics
area of pharmacotherapeutics

– how fast and how much of the drug is absorbed into the body
– how is it distributed to the various organs
– how is it ultimately metabolized and excreted by the body

pharmacodynamics
Area of pharmacotherapeutics

– what a drug does to the body
its beneficial or adverse events at the cellular or organ level
– identify mechanism of action, compare effects of different drugs for potency and efficacy

Toxicology
the study of harmful effects of chemicals

pharmacokinetics
refers to the RATE at which a drug concentration and accumulation are eliminated from various organs of the body – – refers to what the body does to the drug

– describes the drugs action related to LADME

LADME
– Liberation: the process of release of the drug from the formulation
– Absorption – the process of a substance entering the blood circulation
– distribution – the dispersion or dissemination of substances throughout the fluids and tissues of the body
– metabolism – the irreversible transformation of parent compounds into daugheter metabolites
– excretion – the elimination of the substances from the body. in rare cases, some drugs irreversibly accumulate in body tissue

Bioavailability (F)
the measurement or fraction of unchanged (therapeutically active) drug reaching the systemic circulation following administration by any route

(F) = fraction of drug which reaches systemic circulation (bioavailability)

IV-route, F assumed to be 1 (oral route affected by extent of absorption, solubility of drug, first-pass metabolism [first time it goes through & metabolized by the liver])

AUC
the plasma concentration versus time – in relation to bioavailability

bioavailability
factors affecting this include:

– nature of drug formation — absorption may be altered by factors unrelated to the chemistry of the drug
– particle size, salt form, presence of excipents (binders, fillers, dispersing agents) can influence dissolution, and therefore alter the rate of absorption.

Immediate release
– time to peak: 2 hrs
– dosing: 3x/day

IR

Sustained Release
– time to peak: 3 hrs
– dosing: 2x/day

SR

Extended Release
– time to peak: 5 hrs
– dosing: 1x/day

Enteral
a route of adminisration (can affect absorption)

– Oral (PO): most common, dissolve in GI fluid and then penetrate epithelia of intestinal mucosa (duodenum; also some in the stomach)
– Sublingual (SL): gets directly into capillary system, doesn’t need hepatic (liver) metabolism
– Rectal (PR): ~50% of venous drainage in rectal region bypasses hepatic portal, ^metabolism minimized

Parenteral
a route of adminisration (can affect absorption) other than the GI tract

– Intravenous (IV): most common ____ route, 100% absorption
– Intramuscular (IM): forms a “depot” in the muscle
– Subcutaneus (SC): slower than IV route, less painful and easier to administer than IM or IV

*IM and SC route can be errratic!!*

Other Routes
a route of adminisration (can affect absorption)

– inhalation
– intranasal
– intrathecal
– intraventricular
– topical
– transdermal
– intra-articular

Drug solubility
Factor that inhibits drug absorption

– hydrophillic vs hydrophobic
– Drug formation (particle size, salt form, etc.)

Chemical Instability
Factor that inhibits drug formation

– unstable in pH of gastric environment
– destruction by GI enzymes
– physiochemical properties of the drug

Disribution
– How drugs get to the tissues organs via bloodstream
– process by which a drug reversibly leaves blood stream and enters tissues
– rate at which equilibrium between tissue and plasma concentrations is achieved depends on: (bflow, cap. permeability, degree of binding to plasma and tissue proteins, relative hydrophobicity of the drug)

Lipophilic
____ drugs, with no net charge, will move easily across biological membranes.

– will cross the BBB to the CNS and fat tissues for storage

– a drug needs to be largely ____ yet still have some solubility in aqueous solutions

Volume of Distribution
Measure of the apparent space in the body available to contain the drug

High ____ : high conentration in the tissues – good for disease states concentrated in the tissues (pneumonia)

Low ____: drugs contained in the bloodstream – good for disease states in the blood (sepsis)

Geriatrics
This population has:

– decreased body mass (avoid IM injections)
– decreased body water (drugs will be concentrated in the blood)
– increased body fat (more drugs will deposit in fat cells)
– Decreased serum albumin (more free “active” form of drugs will be in the blood)

^^factors of distribution

First-Pass Metabolism
Most drugs absorbed from GI tract –> enter hepatic portal circulation –> encounter liver before they are distributed to the general circulation

Cytochrome P450
Many drug interactions are a result of inhibition or induction of the ______ ____ enzymes.

Drugs that inhibit the enzymes will increase the concentration of drugs that are subsrates for that particular enzyme.

Drugs that induce the enzymes will decrease the concentration of drugs that are substrates for that particular enzyme.

so.. think of it as.. __ ____ like to break down drugs (enzyme = break down). If __ __ is inhibited, a higher conc of drugs will be found

Geriatrics
Special population..

– Liver’s ability to recover from injury is decreased
– heart failure patients: decreased hepatic fxn
– severe nutrition deficiencies

Glomerular filtration
Part of the major organ of excretion (kidneys)

– small, unbound drugs can filter through

Tubular secretion
Part of the major organ of excretion (kidneys)

– most drugs secreted this way – active secretion

Excretion
Most drugs metabolized prior to _____

some pathways include
– kidneys (major organ of ______)
– bile
– sweat
– feces
– saliva
– tears
– exhaled air

Clearance
measure of the ability of the body to eliminate the drug via kidney, lung, liver, other organs

Creatine Clearance
volume of plasma cleared of creatine after parenteral (any way other than through GI tract) administration of a specified amount of the substance

Half-life
– drugs with longer ____ are dosed less frequently (QD)
– Drugs with shorter ___ are dosed more frequently (BID, TID, QID)

– the time required to reduce the drug concentration by half

Geriatrics
Population has: (excretion/elimination)

– Decreased CrCl
– Increased Half-life
– decreased respiratory capacity due to increased pulmonary disease
– closely monitor renally cleared drugs

Drug concentration
– At low doses, responses increase in proportion to doseage
– as doses increase, the response increment deminishes,
– doses may be reached at which no further increase in response can be achieved

Therpeutic Index
Ratio of median lethal dose to the median effective dose
– margin of safety of a particular drug
– drugs w/ low ____ ____ may only require a small increase in dose to produce toxic effects

efficacy
maximum effect of a drug

potency
refers to different doses of two drugs needed to produce the same effect

ex/ morphine 30mg equals in potency to oxycodone 20mg, ^ to manage pain, equal potencies – oxycodone is more potent

Transduction
the process where protein molecules bind with external substances (substrates; hormones, antigens, drugs, NTs), that trigger changes in the fxn of a cell

Full agonist
Part of pharmacodynamics; Receptor-effector coupling
– binds to the receptor and activates it

ex/ albuterol is a beta-2 agonist, when binding to receptor in the respiratory tract it relaxes the smooth muscles and opens the airways

Partial Agonist
Part of pharmacodynamics; Receptor-effector coupling

– produces a lower response than full agonists

Antagonist
Part of pharmacodynamics; Receptor-effector coupling

– binds to and inhibits binding by other molecules
– competitive
– irreversible

ex/ ipratropium is an anti-cholinergic that blocks Ach from binding to receptors. Ach is a NT that constricts smooth muscles

Adreneric
Type of Autonomic Nervous System Receptor

– found on organs stimulated by sympathetic fibers
– noradrenaline (NE) and adrenaline (E) — fight or flight sympathetic response
– innervated by SNS, activated by NEpi, Epi, and ____ drugs

Contain types:
– Alpha: mostly excitatory (except intestine and CNS receptors where inhibition or relaxation occurs)
– beta: mostly inhibitory (except heart where they increase rate and force -*beta blockers*)

Cholinergic
Type of Autonomic Nervous System Receptor

– Acetylcholine receptor (abbv AChR) is an integral membrane protein, responds to binding of ACh, a NT
– main kinds of “______” are muscarinic and nicotinic

Muscarnic Receptors
type of Cholinergic receptor (which is a type of ANS receptor)

– located in SA node, smooth muscle (minus vascular muscle), glands
– NT: ACh, NEpi, Dopa, Hormone receptors
– Action: SA node inhibition, decreased HR, smooth muscle & glands excitation: (increased GI motility, increased secretion)

Nicotinic receptors
type of Cholinergic receptor (which is a type of ANS receptor)

– located in autonomic ganglia of SNS and PNS, neuromuscular jxns, and adrenal madulla
– NT: ACh & nicotine
– action: excitation

dopamine receptors
type of nervous system receptor:
– prominent in vertebrae CNS
– ____ is the primary NT for ____ receptors
– D1, D2, D3, D4, D5
– Implicated in many neurological processes:
motivation, pleasure, cognition, memory, learning, fine motor control

– located in sm. muscle, NT=dopamine, action = dilates renal blood vessels

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