Free NAPLEX Exam Flashcards

A proportionality constant relating the total amount of drug in the body to the plasma concentration. Highly lipophilic drugs have a high Vd (distribute into adipose/tissues); hydrophilic drugs stay in plasma with a lower Vd.

The volume of blood or plasma completely cleared of drug per unit time by all eliminating organs (primarily liver and kidneys). It measures the efficiency of drug removal, distinct from Vd and half-life.

It takes about 5 half-lives to reach steady state with continuous dosing. After 1 half-life ~50%, after 3 ~87.5%, after 5 ~97%. At steady state the rate of administration equals the rate of elimination.

Zero-order: a constant amount is eliminated per unit time (saturated mechanism — e.g., phenytoin at high levels, ethanol). First-order: a constant fraction is eliminated per unit time, which most drugs follow at therapeutic concentrations.

When pH equals pKa, a drug exists 50% ionized and 50% unionized. Unionized forms cross membranes more easily, so this ratio governs absorption and distribution.

Pharmacodynamics = what the drug does to the body (receptor effect, agonism/antagonism, efficacy, potency). Pharmacokinetics = what the body does to the drug (absorption, distribution, metabolism, excretion).

A full agonist can produce a maximal response while occupying only some receptors (spare receptors, high efficacy). A partial agonist cannot reach a maximal response even at full receptor occupancy.

The most abundant hepatic cytochrome P450 enzyme, metabolizing roughly 50% of clinically used drugs (many statins, immunosuppressants, calcium channel blockers, benzodiazepines). Highly susceptible to induction and inhibition interactions.

Codeine is a prodrug converted to morphine by CYP2D6. In CYP2D6 poor metabolizers, analgesic efficacy is reduced. Morphine, oxycodone, and hydromorphone do not require CYP2D6 activation.

Required before starting abacavir; positive patients are at high risk for severe, potentially fatal hypersensitivity. (Compare: HLA-B*15:02 before carbamazepine in certain Asian populations; CYP2C19 for clopidogrel.)

Dissolution rate is directly proportional to surface area. Smaller particle size and micronization increase dissolution; larger particles and hydrophobicity slow it. Basis for many bioavailability-enhancing formulations.

Phase I: safety/PK in healthy volunteers. Phase II: efficacy and side effects in small patient groups. Phase III: large studies confirming efficacy vs standard care. Phase IV: post-marketing long-term and rare-event surveillance.

QD = daily, BID = twice daily, TID (ter in die) = three times daily, QID = four times daily, Q4H = every 4 hours. Misreading these causes dosing errors; for TID x 10 days dispense 30 doses.

OD = right eye, OS = left eye, OU = both eyes; AD/AS/AU = right/left/both ears; gtt = drop. ac = before meals, pc = after meals, hs = at bedtime, prn = as needed.

Schedule I: high abuse, no accepted US medical use (heroin, LSD). Schedule II: high abuse with accepted use (morphine, oxycodone). Schedules III-V: decreasing abuse potential with accepted uses.

Under federal law, Schedule III-V prescriptions are valid for 6 months from issuance with up to 5 refills. Schedule II prescriptions have no federal expiration but must be filled within a reasonable time.

Required elements include patient, drug, strength, form, quantity, directions, prescriber info, DEA number, signature, and date. For Schedule II, the quantity should be written both numerically and alphabetically.

U-100 syringes are calibrated for 100 units/mL insulin; using the wrong syringe causes dangerous dosing errors. U-40 (40 units/mL) is uncommon in the US. Oral syringes are never used for insulin injection.

Required for drugs with serious safety concerns to ensure benefits outweigh risks. Example: isotretinoin iPLEDGE requires prescriber certification, monthly pregnancy testing for childbearing-potential patients, and pharmacy verification before dispensing.

A mechanical (torsion) Class III balance has a 6 mg sensitivity requirement and must be certified annually. For quantities under ~120 mg, a more sensitive analytical balance is preferred for compounding accuracy.

Sterile compounding requires initial competency validation and annual re-evaluation: hand hygiene/garbing, aseptic technique (media-fill testing), and didactic knowledge. Reassess when deficiencies are seen or new procedures are introduced.

Two agents from the same therapeutic class/mechanism prescribed together (e.g., an ACE inhibitor plus an ARB), adding risk (hyperkalemia, renal dysfunction) without added benefit. Contact the prescriber to clarify and discontinue one.

Gather all prescriptions, OTC products, supplements, herbals, and allergies (the brown-bag review). Community pharmacy records typically give the most accurate current list; combine sources for the best reconciliation.

Tools identifying potentially inappropriate medications in older adults. The Medication Appropriateness Index (MAI) assesses indication, dose, directions, interactions, duplication, duration, and cost.

Add a second agent if A1C stays above target after ~3 months on maximum tolerated metformin. With ASCVD, heart failure, or CKD, SGLT2 inhibitors or GLP-1 agonists are preferred for their organ-protective benefits.

GDMT for reduced-EF heart failure: ACE inhibitor/ARB/ARNI, an evidence-based beta-blocker (carvedilol, metoprolol succinate, bisoprolol), a mineralocorticoid receptor antagonist, and an SGLT2 inhibitor as foundational therapy.

Daily short-acting beta-agonist use signals poor control. Persistent asthma needs a daily controller (inhaled corticosteroid or ICS/LABA); the SABA is for PRN rescue only. Frequent SABA use raises exacerbation and mortality risk.

By post-bronchodilator FEV1: GOLD 1 (>=80%), 2 (50-79%), 3 (30-49%), 4 (<30%). The ABCD grouping (symptoms + exacerbation history) guides initial pharmacologic therapy; all COPD patients receive a bronchodilator.

Atrial fibrillation stroke-risk score: oral anticoagulation is recommended at >=2 in men or >=3 in women. DOACs (apixaban, rivaroxaban, dabigatran, edoxaban) are preferred over warfarin for most non-valvular AF.

Allowed down to an eGFR of 30 mL/min/1.73m2; max 1000 mg/day at eGFR 30-45; contraindicated below eGFR 30. Glycemic-control benefits often outweigh risks with dose adjustment and monitoring.

Naloxone is the acute opioid-overdose antidote (IM/IV/SC or intranasal) that reverses respiratory depression by competing at opioid receptors. Naltrexone is for maintenance treatment of alcohol/opioid dependence, not acute reversal.

N-acetylcysteine (NAC) replenishes glutathione and binds toxic metabolites. Most effective within 8 hours; treatment is guided by the Rumack-Matthew nomogram (level vs time since ingestion).

Nystagmus, ataxia, and slurred speech are classic signs. Phenytoin shows zero-order (saturable) kinetics at therapeutic levels (range 10-20 mcg/mL), so small dose increases can cause large concentration jumps.

Current guidelines recommend AUC-guided dosing (target AUC/MIC 400-600) rather than trough-only monitoring, optimizing efficacy while reducing nephrotoxicity, often using Bayesian software.

Rifampin: orange-red body fluids and potent CYP induction. Isoniazid: peripheral neuropathy (give pyridoxine). Ethambutol: optic neuritis. Pyrazinamide: hyperuricemia.

Calcium, iron, magnesium, and aluminum products bind levothyroxine in the GI tract and reduce absorption; separate by at least 4 hours. Coffee, soy, and high-fiber diets also reduce absorption.

Amiodarone inhibits CYP2C9/1A2 and displaces warfarin from protein, raising INR — reduce warfarin ~30-50% and monitor. TMP-SMX similarly inhibits CYP2C9 and displaces warfarin, increasing bleeding risk.

Grapefruit inhibits intestinal CYP3A4 and P-glycoprotein, increasing exposure to CYP3A4 substrates (atorvastatin, simvastatin, cyclosporine, some CCBs). The effect can persist 24-72 hours.

Aged cheeses, aged/cured meats, fermented soy, draft beer, and wine are high in tyramine; with MAOIs this can trigger a hypertensive crisis because gut MAO-A normally degrades tyramine.

Excess serotonergic activity (e.g., tramadol + SNRI, MAOI + SSRI, St. John's wort + serotonergic drugs) causes mental status change, autonomic instability, and neuromuscular signs (clonus, hyperreflexia, rigidity).

Serotonergic antidepressants are contraindicated within 14 days of MAOI discontinuation. Fluoxetine needs a 5-week washout before an MAOI because of its long half-life.

Clarithromycin and erythromycin inhibit P-glycoprotein, increasing digoxin levels 2-3 fold. Reduce digoxin ~50% when starting these macrolides, or switch to azithromycin (less P-gp inhibition).

Magnesium, aluminum, calcium, iron, and zinc chelate fluoroquinolones, cutting absorption 50-90%. Separate by at least 2 hours (4 hours for iron). Tetracyclines and bisphosphonates have the same issue.

Aspirin and NSAIDs raise bleeding risk with warfarin via platelet inhibition and GI injury. Acetaminophen is the safer analgesic choice, though high doses may slightly increase INR.

MedWatch is the FDA program for adverse events, medication errors, and product-quality problems with drugs, biologics, and devices. VAERS is specifically for vaccine adverse events. Reporting is voluntary for clinicians and patients.

Optimizes antimicrobial use through appropriate selection, dose, duration, and route to improve outcomes, slow resistance, reduce adverse effects (C. difficile), and control cost — without eliminating necessary antibiotic use.

Pharmacists generally cannot diagnose or prescribe (except via collaborative practice or protocol). Recommending prescription therapy without evaluation exceeds scope; refer to a licensed prescriber.

Drugs with heightened harm risk when errors occur: anticoagulants, insulin, opioids, chemotherapy, neuromuscular blockers, concentrated electrolytes. Safeguards include limited access, independent double-checks, and standardized protocols.

Class I: reasonable probability of serious harm or death (immediate removal). Class II: remote probability of reversible adverse effects. Class III: not likely to cause adverse effects. Pharmacists must identify and remove affected stock.

Inventory turnover = Cost of goods sold / Average inventory. Higher turnover usually indicates efficient inventory management, but excessively high turnover can signal stockouts. ABC analysis prioritizes counting by item value.