pharm1

Pharmacology

how drugs interact within living organisms to produce biological effects (stop pain, reduce BP, manage depression)

Drugs

chemicals that produce therapeutically useful effects (medication)

quality, safety, efficacy

Drugs have to have license to be used (FDA, EMA), must demonstrate

ADRs

adverse drug reactions

Undesired effect at therapeutic dose

ADR

Aspirin

intestinal distress

Antihistamines

drowsiness

Pharmacovigilance

vigilant and need to have

Overdose

excessive dosing

Elderly more vulnerable because

low liver and kidney function

Allergic reactions examples

penicillins, NSAIDs

Allergic reaction

Drug triggers an immune response (needs prior sensitization, release of histamine)

Allergic reaction causes

causes hives, rash, swelling of face/tongue (angioedema), anaphylaxis (cardiac failure)

Idiosyncratic reaction

adverse effects that cannot be explained

Treat allergic reaction with

antihistamine (mind) or epinephrine (serious)

Dependence

physical (withdrawal syndrome), psychological (craving), opiate drugs

Teratogenic effect

care in pregnancy

Nomenclature chemical name

methyl 2 phenyl 2 acetate

Nomenclature generic name

methylphenidate

Nomenclature brand name

Ritalin

Chemical name

based on the chemical structure

Generic and brand name

When drug is invented gets

non brand name

Non proprietary name

Trade name

brand name, identifies product of a specific manufacturer

Patient protection

20 years

After 20 years

company keeps going, other companies can create other brand names that must contain same genetic “sameness” and “bioequivalence”

Non prescription (OTC)

over the counter, do not need a prescription, mild condition

Prescription element of a drug order

full name and date, drug name, dosage, frequency, route, signature of person writing the order

Drug order ex.

enalapril maleate 10mg id each AM, op, 30

Controlled drugs (drug schedules)

for high addiction and abuse, stringent control as regards use, storage, dispensing and documentation

Drug schedules

correspond to different levels of control (highly Sch 1, loose Sch 5)

Schedule 1

banned drugs (heroin, cannabis)

Schedule 2

legal, highly addictive, very highly controlled (morphine)

Schedule 3

less prone to abuse, care (buprenorphine)

Schedule 4

mild dependence (benzodiazepines)

Schedule 5

small amounts of controlled drugs (codeine cough preps)

*5 rights of drug administration

right drug, right patient, right dose, right route, right time (nurse completes right documentation)

Nurse must know

effects and potential effects of every drug administered

Assess

drug history, lifestyle, physical assessment, lab results

Diagnosis

statement of health problem nurse can treat

Implementation

give treatment, chart records, monitor changes

Evaluation

is it working

Pharmacokinetics

movement of a drug through the body, ADME process

ADME process

Absorption (how drug enters the body), Distribution (how drugs reach their site of action), metabolism, elimination (how drugs are removed from body)

Absorption

movement of drug from site of administration to blood stream (oral, parenteral, nasal, sublingual, buccal, vaginal, transdermal)

Oral absorption

from GI tract (SI), mouth → esophagus → stomach, disintegrate and dissolve in stomach, pass to small intestine → blood, first pass through liver then in blood

Oral absorption advantages

easy, convenient, cheap

Oral absorption barriers

membrane barrier, enzyme activity, acid, first pass effect (hepatic portal circulation)

Oral absorption unsuitable for

nausea, vomiting, diarrhea

Variability

presence/absence of food

Enteric coating

do not crush or chew the tablet (coating resistant to acid, does not damage stomach)

Passive diffusion

Small and hydrophobic

Fastest to slowest

Solution \> suspension \> capsule \> tablet

Parenteral absorption

injection

Intravenous

into vein, rapid response

Subcutaneous

angle under skin, vaccines and insulin

Intramuscular

into muscle; long acting, antipsychotics, contraception (dissolved in oil)

Systemic effect

avoid some disadvantages of oral route

Local effect

nasal

Patch

transdermal

Bioavailability

the rate and extent of drug absorption

IV route

100% bioavailability

Oral route

much lower bioavailability than IV

Cp vs T curves

concentration in plasma

Absorption phase

Cp curve rises during

Elimination phase

Cp curve falls during

Distribution

to the site of action (good), to other sites (bad: waste, unwanted side effects), “magic bullet”:drug targeting

Metabolism

liver! enzyme breaks down drug

Metabolize drug

to smaller, more water soluble compounds, for subsequent elimination in the urine (kidneys)

If liver damage

drugs will not be metabolized, drug stays in the body which can accumulate to toxic levels

Liver breaks down drug

and metabolite through enzymes

Liver function

measure enzyme levels, hepatic damage (drugs, alcoholics, elderly)

Reduced liver function

decrease the dose / increase the dosing interval (every 12 hours instead of 4)

Measure liver function

enzyme levels

Liver first pass effect

(liver then to the rest of body), may have to avoid oral route

GTN (glyceryl trinitrate)

angina (can't give orally will be destroyed by liver) avoids first pass effect

Metabolic interaction

drug can induce or inhibit liver metabolizing enzymes

Induction of liver metabolizing enzymes

increase synthesis of enzymes, (drug A induces enzymes which degrade drug B making B less effective)

Pill is less effective

Phenytoin induces liver enzymes which metabolize the contraceptive pill

Inhibition of liver metabolizing enzymes

drug A can inhibit the degradation of drug B which increases toxicity of B

Elimination

kidney excretion; eliminated in the urine with/without biotransformation by the liver

Measure kidney function

creatinine clearance

Care with kidney damage

drugs, elderly

If kidney damage

drug will not be eliminated and stays in body, can lead to toxic levels

If reduced liver function

decrease the dosage or increase the interval

Process

Absorption, Distribution, Metabolism, Elimination

Minimum effective

smallest amount to see an effect

Therapeutic concentration

concentration that gives desired effect

Minimum effective concentration

minimum concentration required for therapeutic effect

Toxic concentration

concentration at which toxic effect begins

Therapeutic range

range of plasma drug levels between MEC and toxic concentration

Onset of drug action

time taken to get response

Duration of action

time in therapeutic range

Half life

time for amount of drug to decrease by 50%

Therapeutic index

difference in therapeutic dose and lethal dose

1000

wide TI

2

narrow TI

Risk of OD

narrow TI (not as safe)

Repeated dosing

reach steady state (after 4 half lives)