Pharmacology: Drug Efficacy, Safety, Absorption, and Metabolism

What does it mean for a drug to be effective?

It elicits the desired response.

What does it mean for a drug to be safe?

The drug does not have harmful side effects, especially if it needs to be given at high doses for a long time.

What does it mean for a drug to be selective?

It only has the desired response.

Why is ease of administration important?

It decreases risk of harm and increases patient adherence to their medication.

Is there such a thing as a drug that is 'safe' for every individual?

No, all drugs have the potential for side effects.

Give an example of a drug that is not selective.

Diphenhydramine (Benadryl) which causes drowsiness in addition to clearing allergy symptoms.

What is the serum creatinine level indicative of?

If it is HIGH, the kidney is not working and is unable to filter.

What does GFR stand for and what does it indicate?

Glomerular filtration rate; if it is LOW, the kidney is not working.

What do LFTs measure?

They measure liver enzymes and substances like bilirubin that leak from the liver or build up in the blood.

What happens if LFTs are HIGH?

The liver is not working well, and symptoms may include upper abdominal pain, loss of appetite, and jaundice.

What is absorption in pharmacokinetics?

Movement of a drug from its site of administration to the blood.

What are the barriers for oral drug absorption?

The drug must reach the small intestine to be absorbed.

Rank the routes of administration from fastest to slowest onset of action.

IV, IM/subQ, PO.

What are Enteric-Coated preparations?

They have a coating to ensure that they dissolve in the small intestine, not the stomach.

What are Sustained-Release preparations?

Capsules with tiny spheres that release the drug over a longer period.

Can Enteric-Coated and Sustained-Release preparations be cut or crushed?

No, cutting or crushing would destroy the coating.

What is the first pass effect?

It is when a drug's concentration is reduced before it reaches circulation.

Which routes of administration avoid the first pass effect?

Routes that do not involve the digestive system, such as intravenous.

What can the liver do to drugs that it takes up?

Activate, deactivate, convert to a toxin, or excrete them.

Which drugs pass readily through the cell membrane?

Lipid soluble drugs.

Which drugs have trouble passing through the cell membrane?

Water soluble, ionized, and polar molecules.

What is the blood-brain barrier?

A barrier that prevents most drugs from crossing into the brain.

What is protein-binding in pharmacology?

When a drug binds to a protein in the bloodstream, lowering the amount of free drug available.

What happens when another highly-protein bound drug is introduced?

It competes for the same binding spots, affecting free drug levels.

What does a CYP450 enzyme inducer drug do?

It increases the metabolism of other drugs, decreasing their levels.

What does a CYP450 enzyme inhibitor drug do?

It decreases the metabolism of other drugs, increasing their levels.

Is grapefruit juice a CYP450 inhibitor or inducer?

It is a CYP450 inhibitor.

What effect does grapefruit juice have on medication levels?

It prevents the breakdown of drugs, leading to higher medication levels in the blood.

What is the definition of drug half-life?

The time it takes for the concentration of the drug in the blood to reduce by half.

What is transdermal medication release?

It releases medication at a controlled amount over a longer period, bypassing the intestines.

What is drug half-life?

The time required for the amount of drug in the body to decrease to 50%.

What determines the frequency of dosing for a drug?

The half-life of the drug.

How many half-lives does it take for a drug to reach a plateau?

Four half-lives.

What is the therapeutic range?

The range between the minimum effective concentration and the toxic concentration.

What is toxicity in relation to drugs?

When plasma drug levels are too high.

Is toxicity more likely with a small or large therapeutic window?

Small therapeutic window.

What type of monitoring is done for drugs with small therapeutic windows?

Careful dosing and monitoring.

What is a loading dose?

A larger amount of drug given with the first dose to achieve a quicker therapeutic effect.

Can pH affect drug absorption and excretion?

Yes, changes in pH can affect absorption and excretion.

What is a receptor in pharmacology?

Any functional macromolecule in a cell to which a drug binds to produce effects.

What substances act on receptors?

Ligands.

Why are selective drugs desirable?

They maximize therapeutic capacity while minimizing side effects.

What is an agonist?

Molecules that activate receptors.

What is an antagonist?

Molecules that prevent receptor activation.

What is a partial agonist?

A molecule that can act as both an agonist and antagonist, with moderate intrinsic activity.

What is medication reconciliation?

The process that reduces medication omissions, duplications, and dosing errors.

When should medication reconciliation be conducted?

During a transition in care.

Why should the abbreviations q.d and q.o.d be avoided?

They can be confused with every day, every other day, or four times a day.

Why should a decimal always be preceded by a zero in drug dose orders?

To lower the chance of misreading the dose.

Why should trailing zeros be avoided in drug dose orders?

To prevent misreading the dose as a larger amount.

What is a time-critical medication?

A medication where a missed dose can cause serious harm and must be taken on time.

Can all drugs cross the placenta?

Yes, all drugs can cross the placenta.

Are drugs in pregnancy well-studied?

No, they are not well studied.

Why should pregnant patients not necessarily stop medications?

Risks of untreated conditions may be worse for the baby.

What is the preimplantation period?

Conception to 2 weeks.

What is the embryonic period?

Weeks 3-8.

What is the fetal period?

9 weeks to term.

During which period are teratogenic effects most likely to occur?

During the embryonic period.

How does pregnancy affect renal blood flow?

Renal blood flow is doubled by the third trimester.

What happens to plasma volume during pregnancy?

It expands.

What risk do NSAIDs pose if used heavily during pregnancy?

They can cause premature closure of the ductus arteriosus.

Which drugs are more likely to be excreted in breast milk?

Lipid-soluble drugs.

When should a nursing mom take her medications to minimize baby's exposure?

Right after feeding.

Why are children, especially newborns and infants, sensitive to drug effects?

Their organ systems are not fully developed.

How does absorption differ in newborns compared to adults?

Gastrointestinal makeup is different, affecting drug effects.

How does distribution of drugs differ in newborns?

Less proteins in blood to bind to, making effects more intense.

How does metabolism differ in newborns?

They have low drug-metabolizing capacity.

How does excretion differ in newborns?

Renal drug excretion is lower, requiring lower doses.

How does topical drug use in infants compare to older children?

Topical drugs are absorbed more rapidly in infants.

When does liver maturation happen in infants?

At year 1.

How does renal drug excretion change until year one?

It is lowered, requiring lower drug doses.

What is different about the infant's skin compared to older children and adults?

It is much thinner.

How does gastric pH in a one-year-old differ from that of a four-year-old?

The pH is lower in a one-year-old, increasing absorption of acid-labile drugs.

When does kidney function mature to adult levels in children?

At 1 year.

How do albumin levels in newborns/infants compare to older children?

They are much lower.

How should dosing of highly protein-bound drugs be adjusted for newborns?

Dosing should be lower.

What can aspirin cause in children?

Reye syndrome.

What can sulfonamide antibiotics cause?

Liver failure.

What can tetracycline antibiotics cause?

Tooth discoloration and hypoplasia.

How is the pediatric dose determined?

Child's body surface area times the adult dose, divided by 1.73 m².

How is drug absorption affected in older adults?

Absorption may be slowed and drug responses delayed.

Which organ almost universally declines in function in older adults?

Kidneys.

Why do we use creatinine clearance to measure kidney function in older adults?

Serum creatinine source (lean muscle mass) declines with kidney function.

How does body composition change in older patients compared to young adults?

Increased body fat, lower lean mass, decreased total body water, reduced serum albumin.

Are serum albumin levels higher or lower in older adults?

Lower.

How does the blood-brain barrier change in older adults?

Tight junctions break down, making it more permeable.

Why are adverse drug reactions more common in geriatric patients?

More medications taken, variability in drug effects, and potential for incorrect medication use.

Should drug doses be lower or higher in older patients?

Lower doses are usually needed.

What are the effects of anticholinergic drugs in treating urge incontinence?

They stop the bladder from involuntarily contracting.

What is the mechanism of the drug physostigmine?

Inhibits acetylcholinesterase, boosting ACh levels.

What does it mean to be a sympathomimetic drug?

Mimics the fight or flight response.

What does it mean to be a parasympathomimetic drug?

Mimics rest and digest, boosting effects of acetylcholine.

Where are baroreceptors located?

In the carotid sinus and aortic arch.

What are the four big anticholinergic side effects?

Can't see, can't spit, can't pee, can't sh**.

What are Beer's Criteria?

A list of medications to use with caution in people over 65.

What is the prototype cholinergic antagonist drug?

Atropine.

What transmitters bind to alpha 1, beta 1, beta 2, and dopamine receptors?

Epinephrine and norepinephrine.

What transmitter binds to a muscarinic receptor?

Acetylcholine.

What are the major adverse effects of atropine?

Increases heart rate, decreases secretions, causes delirium and hallucinations.

What is the effect of anticholinergic drugs on the bladder?

They allow the bladder to hold more urine.