superpharm

Pharmacokinetics

How the drug moves and modifies in the body

Features absorption, distribution, metabolism, and excretion (drug elimination/clearance mechanisms)

Absorption

Route of administration to the bloodstream

Distribution

How drugs circulate from the bloodstream to target cells. Carried by the blood and tissue fluids

Affected by drug-protein binding and circulation

Metabolism

AKA biotransformation

Drugs being altered from their original form to a new form done by cytochrome p-450 (CYP) liver enzymes

Inactivates drugs, but activates prodrugs

Excretion

Elimination of drug metabolites (mainly) and drugs from the body

Adequate circulation and excretion organ (kidneys, bowels, lungs, skin) function enables

Protein binding

Drugs bound to plasma proteins/carriers (mainly albumins) remain inactive d/t being unable to diffuse through capillaries. However, carriers can store and release drugs PRN

Affects distribution

Pharmacodynamics

Drug action and how it works/makes the body react

Affected by: body comp, genes, immature organs

Agonist

Produces similar effects to naturally occurring hormones, NTs, and other substances, accelerating/slowing normal cellular processes

Antagonist

Inhibits cellular function by occupying receptors

Antidote

Relieves, prevents, or counteracts toxic effects of another drug/poison

Hypersensitivity

An immune-mediated reaction (allergy) to a drug that occurs in pts who have developed antibodies to the drug or to a similar antigen

Serum drug level

Lab measurement of the amount of drug in the blood at a particular time

Reflects: dose, absorption, bioavailability, half-life, and rate of metabolism and excretion

Serum half-life

Time it takes for the serum concentration of a drug to decrease by half

Determined by the drug’s rate of metabolism and excretion

When it’s longer, the f of drug administration decreases

When it’s shorter, the f of drug administration increases

Loading Dose

A beginning dose that’s larger than normal to rapidly increase therapeutic serum drug level

Maintenance Dose

Quantity of drug needed to maintain blood and/or tissue levels stable or constant

Nephrotoxicity

The intra-renal damaging effects of drugs → nephritis/decreased kidney f(x) → decreased GFR → increased drug accumulation and half-life → increased adverse effects

Adverse effects

Unpredictable responses from a drug

Harmful

Call provider

Primary actions

Intended/therapeutic effects

Secondary actions

All other side effects that exclude intended (primary) ones

First-pass effect

When a large amount of oral dose is destroyed upon reaching the liver, before reaching body tissues

Bioavailability

Portion of the dose that reaches systemic circulation and is available to act on body cells

Tyramine-rich (fermented) foods

Should be avoided when on MAO inhibitors d/t the inability to inhibit NE (vasoconstrictor)

1 hour a.c. or 2 hours p.c.

Timing for giving meds to limit drug-diet interactions (can inhibit drug absorption to an extent; drug-drug interactions tend to be more limiting though)

Boxed warning

Serious/life-threatening adverse effects

Alleviating adverse effects

When trying to get a pt to go on new medication while promoting safety, mention:

Activated charcoal

Common OD antidote

Ensure that the unconscious pt’s airway is secure before administering. Laxatives also aid in the removal of the charcoal-drug complex, preventing bowel obstruction

Poison control

Contact when the victim is responsive

911

Contact when the victim is collapsed or not breathing

Blood dyscrasia

Any disorder/abnormality of the blood

Symptoms: Fever, chills, sore throat, back pain, weakness

Anaphylactic shock

Allergic reaction (t1 hypersensitivity)

Symptoms: immediate onset, nausea, paleness, diaphoresis, coughing and wheezing (signifies expiratory obstruction), pruritis (itching), rash, hives (urticaria), dilated pupils, anxiety, rapid HR, respiratory arrest

Antipsychotics

Decreases brain dopamine levels

Secondary actions resemble Parkinson’s d/t that

Side effects: Tremors, drooling, gait changes, restlessness, akathisia, dyskinesia, stiffness

Med error categories

A through I

A is when circumstances have capacity to cause error; I is when the error caused the pt’s death

Diuretics

Black pts respond less to ACE inhibitors and beta-adrenergic blocking drugs when treating heart failure/HTN

Give this instead

Side effects

Predictable responses from a drug

Can be problematic, but NOT Harmful

No need to call provider

BBB

capillaries with tight bonds in the cns, preventing most ions, large molecules, and drugs from the bloodstream entering the brain

poorly developed in newborns

Body surface area

square meters of the human body surface: (root of: cm x lbs/3600)

calculated using weight

used for dosage calculation in peds: (bsa/1.73)(adult dose)

Total body water

Amount of water in the body both intracellularly and extracellularly

Can influence drug effectiveness

Changes throughout childhood (ex: infants are 80% water; adults 60%)

Affects absorption

• Age

• Disease process

• Route of administration

• Decreased/irregular/weak gastric emptying and intestinal motility→decreased absorption

• Increased skin permeability→increased absorption

• Decreased vasculature to muscles→IM injections unpredictable (also hurts for the kid). If necessary, children up to 3 get injected (with a 25 gauge needle) in the vastus lateralis d/t size and vasculature

Affects distribution

• Increased total body water of peds→water-soluble drugs dilute easier→increased dose to maintain therapeutic drug levels

• Immature BBB→increased permeability→affects CNS

• Immature liver→decreased protein production→decreased protein-drug binding→increased drug serum concentration and risk for toxicity

Affects metabolism

• Immature liver→decreased drug metabolism→increases risk for toxicity and half-life

Affects excretion

• Immature kidneys→decreased GFR→increases drug accumulation, half-life, and risk for toxicity

Neonate

0-4 w

Infant

4 w - 1 y

Child

1-12y

Adolescence

12-18y

Immature body systems

The reason for why children respond so differently to drugs and why drug therapy is dramatically changed

12y

Age when pharmacokinetic responses resemble adults

2y

Age liver matures

Pediatric drug reference

If there is no label dosage info (gold standard), use a:

Administration and monitoring

2 important things for drug safety of children

Empowering them

Kids can’t grasp being educated of their meds, so to convince them to take them by:

Age-related changes

physiologic events d/t increased age, affecting drug responses

• often occur in midlife (ex: <3 disease, pulm insufficiency, cancer, arthritis, DM, obesity, substance use, depression)

• decreased receptors and weaker receptor binding→decreased sensation and agonist f(x)

Polypharmacy

taking multiple drugs at once

• d/t treatment of chronic illness and associated comorbidities

• drug-drug interactions can cause→increase complications and decrease mental status

Risk to benefit ratio

adverse effects in relation to desired (primary) effects

• increases with age

Beers criteria

list of meds meant for geriatrics that result in significant adverse effects

• includes dose adjustments based on decreased kidney f(x): so, be sure to lower doses and increase monitoring

• meds administered in hospice and palliative care don’t count on the list

• opioid usage requires pt assessment and response to treatment

Affects absorption

• decreased gastric acidity (increased pH)→delayed absorption

• decreased gastric blood flow and SA→decreased absorption

• decreased gastric emptying→nausea and vomiting→premature drug elimination AND decreased fluid vol (leading to decreased drug distribution)

• decreased muscle blood flow→decreased absorption of IM and SUBq administration

• slow absorption→changes in peak serum drug levels

Affects distribution

decreased CO, increased body fat, decreased body mass, decreased body fluid, decreased serum albumin

• lipid-soluble drugs stay and stores itself in adipose for longer (ex: anesthetics)

• water-soluble drugs decrease in distribution d/t decreased fluid vol

Affects metabolism

age-related physiological change of the liver affects this

decreased liver size/mass AND decreased hepatic circulation →lowers rate of metabolism

Affects excretion

changes in this aspect is associated with age-related physiological changes:

• decreased renal perfusion, nephron f(x), GFR, and tubule secretion

• decreased creatinine clearance requires pt to be administered a smaller dose to prevent adverse effects and toxicity

  • normal Cr levels could be d/t less muscle mass to produce Cr

Non-adherence

taking a med more or less than indicated

Nursing intervention

this should be based on the immediate, presented issue at hand

Prevention of adverse effects

assess:

• pt’s health history and lists of meds taken (OTC, prescribed, herbs)

• BUN/Cr clearance levels (to determine excretion ability)

• ratio of liver f(x)

• therapeutic drug levels to determine effectiveness and prevent toxicity

• pt’s adherence to meds (provide pt with med administeration aids to increase)

educate pt and family of:

• all meds and drug-drug, drug-herb, and drug-diet interactions

• generic and trade names to prevent overmedication

• using 1 PCP who prescribes meds in consultation with other HC specialists

• having all meds filled at 1 pharmacy

Albuterol

Salmeterol, formoterol

Theophylline

Ipratropium

Tiotropium

Beclomethasone, fluticasone

Prednisone

Diphenhydramine

Loratadine

Montelukast

Cromolyn

Bethanechol

another side effect: urinary urgency (urge to urinate plus leakage)

Atropine

Pyridostigmine

Epinephrine

used for cardiac arrest

Dopamine

used to perfuse tissues post-cardiac arrest

Propranolol

also decreases inotropy→decreases cardiac (O2) demand

Metoprolol

also decreases inotropy→decreases cardiac (O2) demand

How to assess for shock

Delirium, low BP, peripheral vasoconstriction, cold/clammy/pale/cyanotic extremities, low pulse, lack of capillary refill

Extravasation

Fluid outside BVs→necrosis, sloughing, and genrene

A boxed warning for DA, E, and NE

Anaphylaxis symptoms

Respiratory: coughing and wheezing (obstructive problems), chest tightness, itchy throat, trouble breathing

Skin and Mucosa: hives, pruritis, angioedema, flushing

GI: vomiting, diarrhea, and abdominal pain d/t shutting off rest and digest f(x)s

Low BP: syncope, anxiety, confusion, irritability, feeling faint, feeling doom

Angioedema

Swelling under the skin

Propranolol

lowers BP and HR
also treats migranes and esophageal varicosities

Metoprolol

lowers BP and HR

Carvedilol

lowers BP (especially) and HR

Losartan

lowers BP

less likely to cause hyperkalemia and angioedema

bradykinen is broken down→less vasodilation than ACE inhibitors, but no dry cough or increased risk for angioedema (also used when ACE inhibitors cause an adverse reaction, such as, angioedema)

Lisinopril

lowers BP

more likely to cause hyperkalemia and angioedema

bradykinin breakdown is prevented→dry cough, prolonged vasodilation, increased risk for angioedema

Verapamil (<3), amlodipine (BVs; prototype)

lowers BP and HR (in some cases)

Prazosin

lowers BP

Furosemide (Lasix)

Spironolactone

weak diuretic (takes a while for effects to kick in and be absorbed orally, short half-life, effects aren’t much)

Hydrochlorothiazide

weak diuretic that is most effective c adequate urine flow, but often remains the diuretic of choice

Mannitol

Nitroglycerin

Nitroprusside

Hydralazine

Minoxidil

Digoxin

Lowers HR