Pharmacology Basics Quiz

Basic Terms

• Drug - any chemical affecting living processes
• Pharmacology - study of drugs and their interactions with living systems
• Clinical Pharmacology - study of drugs in humans
• Pharmacotherapeutics - the use of drugs for diagnosis, prevention, or treatment of disease, or to prevent pregnancy

Properties of the Ideal Drug

• Effectiveness - a drug must be effective before marketing
• Safety - although all drugs have some harmful effects, proper dosing and selection can mitigate harm
• Selectivity - ideally, a drug elicits only the desired response

More Ideal Characteristics

• Reversible Action - the drug's effect should be temporary
• Predictability - patient response varies, and reactions to a drug cannot be perfectly predicted
• Ease of Administration - administration should be straightforward
• Freedom from Drug Interactions - drug interactions should be minimized
• Low Cost - drug cost is a factor, particularly considering generic options
• Chemical Stability - drugs should maintain integrity, especially when exposed to moisture
• Possession of a simple generic name - for easier identification

Pharmacokinetics

• Absorption, distribution, metabolism, and excretion (ADME) involve drug movement across cell membranes
• Cell membranes are primarily composed of phospholipids; drugs must be lipid soluble to cross the membrane
• Pharmacokinetics describes the amount of administered drug that reaches the site of action (via drug absorption, distribution, metabolism, and excretion)
• Individual variations (i.e., kidney or liver impairment) can affect how a drug reaches its intended target (affecting drug efficacy)

Passage of Drugs Across Cell Membranes

• Channels/pores: small ions (like K/Na) can pass
• Transport Systems: drug structure affects specific transport systems, some require energy, others do not
• Direct Penetration: lipid-soluble drugs can pass through the cell membrane directly

Bioavailability

• Ability of a drug to reach systemic circulation from its administration site
• Factors affecting bioavailability: tablet disintegration time, enteric coatings, sustained-release formulations, gastric pH, diarrhea, constipation, food in the stomach

Absorption

• Movement of a drug from its administration site into the bloodstream
• Rate of absorption influences when drug action begins
• Factors influencing absorption: drug solubility, surface area, blood flow

Dosage and Administration

• Dosage can vary based on indication
• Dosage can depend on administration route

Routes: Intravenous (IV)

• Rapid onset, precise control of drug delivery, large volumes can be delivered
• Disadvantages: expensive, difficult, inconvenient; special training required, risk of toxicity, fluid overload, and infection

Routes: Intramuscular (IM) and Subcutaneous (SQ)

• Advantages: quick absorption (slower than IV), can be used for depot absorption (e.g. depot penicillin G)
• Disadvantages: painful, limited injection sites, risk of bleeding, less convenient for many patients

Routes: Oral (PO)

• Easily accessible, avoids invasive procedures
• Disadvantages: can be highly variable in absorption
• Other routes: inhalation, rectal, vaginal, topical (creams, ointments), transdermal

Pharmacokinetics

• Drug binds to a receptor once it reaches its intended site.
• Tolerance and naivety, placebo effects, receptor impairment, and interference from other drugs can influence the efficacy of drug binding and the amount of drug absorbed

Protein Binding (Albumin)

• Free, unbound drugs can leave the vascular space for target tissue.
• Binding is reversible and depends on the strength of attraction between the drug and the binding protein.

Drug Distribution

• Drugs are carried to tissues via the circulatory system

• Factors affecting distribution: vascular space access, tight junctions between the cells, capillaries, and abscesses/tumors

• Blood-brain barrier (BBB) - lipid-soluble drugs can penetrate; barrier isn't fully developed in newborns/fetuses

Drug Naming

• Chemical, generic, brand names for drugs

Pre-Administration Assessment

• Gathering baseline info from patient and family (drug names, dosages, purposes, administration times)
• Identifying high-risk patients (e.g., liver/kidney impairment, allergies, pregnancy)
• Evaluating therapeutic responses and adverse events (AEs) after drug administration

Routes of Drug Administration

• IV - no barriers to absorption
• IM - capillary wall barrier
• SubQ - same as IM
• Oral (PO) - various barriers

Nursing Role In Changing Routes

• Assessment for potential problems, e.g., choking on tablets, if the route should be changed, or other patient safety concerns

Metabolism of Drugs

• Drugs are biotransformed (altered) in the liver by cytochrome P450 enzymes (CYP1, CYP2, CYP3)
• Metabolism often results in drug excretion in the kidneys (most importantly)

Considerations in Drug Metabolism

• Age affects drug metabolism (limited in infants and decreased in older adults)
• First-pass metabolism affects oral drugs to a significant degree

Drug Excretion

• Removal of drugs from the body (kidneys are most important organ)

Time Course of Drug Responses

• Drug absorption, distribution, metabolism, and excretion determine how much drug reaches the target site.

Drug Half-Life

• The time it takes for a drug's concentration to decrease by 50%.

Drug Binding (Agonists and Antagonists)

• Agonists activate receptors, similar to naturally occurring molecules
• Antagonists block receptors, preventing activation by other molecules

Drug-Drug Interactions

• Multiple drug use interactions influence therapeutic outcome
• Pharmacokinetic, pharmacodynamic, and combined toxicity can occur

Clinical Significance and Therapeutic Index

• Drug interactions can significantly change therapeutic outcome

• Therapeutic index (LD50/ED50 ratio) measures drug safety

• A higher index = safer drug for the population

• Lower index = less safe drug

Drug-Food Interactions

• Grapefruit can affect drugs
• Drug Interactions with certain foods need to be considered with medication use

Adverse Drug Reactions (ADRs) and Medication Errors

• Undesired effects occurring at normal drug doses
• A wide range of intensities to severe outcomes

Side Effects

• Common or predictable responses associated with the medication
• Predicting the intensity of side effects is related to the drug dose.

Allergic Reactions

• An antibody-mediated response to the drug
• Reactions can vary, ranging from mild to life threatening

Idiosyncratic Effects

• Unique/uncommon drug responses due to genetic factors/unknown reasons, are not predictable

Medication Reconciliation

• Processes to verify the correct drug dosages for patients at transitions of care (e.g., hospital admissions or discharges) to avoid medication errors

Medication Errors

• Errors are common in medication administration; many errors are due to human factors / poor planning.
• Steps must be taken to avoid errors, e.g., correct procedures and communication

Ways to Reduce Medication Errors

• Encouraging active patient/family participation
• Educating healthcare team members
• Creating strategies for error reporting

Test your knowledge on the fundamental concepts of pharmacology, including definitions and properties of ideal drugs. This quiz covers key terms and characteristics essential for understanding drug interactions and their clinical applications.