Pharmacology – RN Flashcards

Flashcards at registered nurse depth. Cover the term, then recall the answer before revealing it.

Pharmacokinetics and Principles

What is the first-pass effect and why does it matter clinically?

Oral drugs absorbed from the gut pass through the portal circulation and are metabolized by the liver before reaching systemic circulation. It explains why oral doses are larger than intravenous doses of the same drug, and why sublingual, transdermal, rectal, and parenteral routes bypass hepatic metabolism and yield higher bioavailability.

How many half-lives are needed to reach steady state, and why does that matter?

About four to five half-lives on a fixed dosing schedule. It explains delayed therapeutic effect, the use of loading doses when rapid effect is needed, and the time required for a drug to clear after discontinuation.

Why does hypoalbuminemia increase the risk of drug toxicity?

Only the unbound (free) drug fraction is pharmacologically active. With low albumin, a larger free fraction circulates, so highly protein bound drugs such as warfarin and phenytoin produce exaggerated effects at ordinary doses.

Name common cytochrome P450 inducers and inhibitors and their effect on serum drug levels.

Inducers such as rifampin, phenytoin, carbamazepine, phenobarbital, and St. John's wort increase metabolism and lower levels of other drugs. Inhibitors such as azole antifungals, erythromycin and clarithromycin, and grapefruit juice decrease metabolism and raise levels, increasing toxicity risk.

Define narrow therapeutic index, list classic examples, and state when a trough is drawn.

A small difference between the therapeutic and toxic dose, requiring serum level monitoring. Examples: digoxin, lithium, phenytoin, theophylline, warfarin, vancomycin, and aminoglycosides. The trough is drawn immediately before the next scheduled dose; the peak, drawn after administration at a drug-specific interval, reflects toxicity risk.

Cardiovascular and Hemodynamic

Digoxin

therapeutic range, precipitating electrolyte abnormality, toxicity signs, and antidote?

Range 0.5 to 2.0 ng/mL overall, with 0.5 to 0.9 ng/mL targeted in heart failure. Hypokalemia potentiates toxicity and is common with concurrent loop diuretics; hypercalcemia and hypomagnesemia also increase risk. Toxicity presents as anorexia, nausea, vomiting, fatigue, visual disturbance including yellow-green halos, bradycardia, and dysrhythmias. Antidote is digoxin immune Fab.

Why must nitrates never be given with a phosphodiesterase-5 inhibitor?

Combined vasodilation causes profound, refractory hypotension and cardiovascular collapse. Avoid nitrates within about 24 hours of sildenafil or vardenafil and about 48 hours of tadalafil.

What is the nursing priority when a vasopressor such as norepinephrine extravasates?

Stop the infusion, disconnect the tubing while leaving the catheter in place to aspirate residual drug, notify the provider, and infiltrate the area with phentolamine as ordered to reverse local vasoconstriction and prevent necrosis.

Two major toxicities unique to sodium nitroprusside?

Cyanide and thiocyanate accumulation with prolonged or high-dose infusion, and light sensitivity requiring the container to be protected from light. Monitor for metabolic acidosis and altered mental status.

Most serious long-term adverse effect of amiodarone?

Pulmonary toxicity progressing to fibrosis. Also thyroid dysfunction in both directions, hepatotoxicity, corneal microdeposits, blue-gray skin discoloration, and QT prolongation.

Anticoagulation

Heparin infusion

monitoring target, antidote, and the complication to watch for?

Target aPTT is generally 1.5 to 2.5 times the control value, or an anti-Xa level per protocol; the antidote is protamine sulfate. Watch for heparin-induced thrombocytopenia, an immune-mediated fall in platelet count typically 5 to 10 days after exposure that paradoxically causes thrombosis. If suspected, stop all heparin including flushes and heparin-coated devices, notify the provider, and anticipate a nonheparin anticoagulant such as argatroban.

Target INR ranges for warfarin?

2.0 to 3.0 for atrial fibrillation and venous thromboembolism, and 2.5 to 3.5 for a mechanical mitral valve. Antidote is vitamin K, with prothrombin complex concentrate or fresh frozen plasma for urgent reversal.

Key nursing points for subcutaneous enoxaparin administration?

Give in the abdomen at least 2 inches from the umbilicus, do not expel the air bubble in the prefilled syringe, do not aspirate, and do not massage the site. Dose is reduced in renal impairment, and routine coagulation monitoring is usually not required.

High-Alert and Critical Care

Why is concentrated potassium chloride never given intravenous push, and what are the safe parameters?

Rapid delivery causes fatal cardiac arrest. Always dilute and infuse by pump, generally no faster than 10 mEq per hour through a peripheral line, with higher rates only through central access with continuous cardiac monitoring per policy. Verify adequate urine output first.

Which insulin can be given intravenously?

Regular insulin is the only insulin routinely given intravenously.

In diabetic ketoacidosis, what is done when the glucose falls to about 200 to 250 mg/dL?

Add dextrose to the intravenous fluid and continue the insulin infusion, because the endpoint of therapy is closure of the anion gap and clearance of ketosis, not normalization of glucose. Monitor potassium closely, since insulin drives potassium intracellularly.

What must always accompany a neuromuscular blocking agent?

Adequate sedation and analgesia, plus a secured airway and mechanical ventilation. These agents paralyze without providing sedation or pain relief, and they are a high-alert class requiring independent double checks.

Which medication classes require an independent double check?

Insulin, anticoagulants such as heparin, opioid infusions and patient-controlled analgesia, chemotherapy, concentrated electrolytes, vasoactive infusions, and pediatric or neonatal high-alert doses. The second clinician verifies independently, without being told the expected values.

Signs of magnesium sulfate toxicity and the antidote?

Loss of deep tendon reflexes first, then respiratory depression, oliguria, hypotension, and cardiac arrest. Stop the infusion and administer calcium gluconate.

Neurologic, Psychiatric, and Analgesic

Distinguish serotonin syndrome from neuroleptic malignant syndrome.

Serotonin syndrome has rapid onset within hours, with hyperreflexia, clonus, tremor, agitation, diaphoresis, and hyperthermia after serotonergic drug exposure. Neuroleptic malignant syndrome develops over days after dopamine antagonist exposure, with lead-pipe rigidity, hyporeflexia, high fever, altered mental status, autonomic instability, and elevated creatine kinase.

Therapeutic lithium range and early toxicity findings?

0.6 to 1.2 mEq/L, with toxicity above 1.5 mEq/L. Early findings are nausea, vomiting, diarrhea, fine tremor, and thirst; later findings are coarse tremor, ataxia, confusion, and seizures. Dehydration, sodium restriction, thiazides, NSAIDs, and ACE inhibitors all raise the level.

Therapeutic phenytoin range and administration cautions?

10 to 20 mcg/mL. Give intravenous phenytoin in normal saline only, never dextrose, and infuse slowly with cardiac monitoring because of hypotension and dysrhythmia risk. Toxicity presents as nystagmus, ataxia, and slurred speech. Chronic use causes gingival hyperplasia.

What must a client on a monoamine oxidase inhibitor avoid, and why?

Tyramine-rich foods such as aged cheese, cured or smoked meats, fermented soy products, tap beer, and overripe or fermented foods, because they can precipitate hypertensive crisis. A washout of about 2 weeks is required when switching to or from an SSRI.

Antidotes to memorize for the analgesia and sedation family?

Naloxone for opioids, noting its shorter duration than most opioids so repeat dosing may be needed; flumazenil for benzodiazepines, used cautiously because it can precipitate seizures in chronic users; and acetylcysteine for acetaminophen overdose.

Anti-infective and Oncology

Vancomycin infusion reaction

cause and management?

Direct histamine release from rapid infusion, producing flushing and erythema of the face, neck, and upper torso with pruritus. Stop or slow the infusion, treat with an antihistamine as ordered, and extend the infusion to at least 60 minutes. It is not an IgE-mediated allergy and should not be charted as one.

Two hallmark toxicities of aminoglycosides, and the monitoring required?

Nephrotoxicity and ototoxicity. Monitor peak and trough levels, serum creatinine, urine output, and hearing, and report new tinnitus, vertigo, or hearing loss.

What is the chemotherapy nadir and what teaching accompanies it?

The point of lowest blood counts, typically 7 to 14 days after administration. Teach infection precautions, avoidance of crowds and raw foods per protocol, bleeding precautions, and immediate reporting of a temperature of 38 degrees Celsius or 100.4 degrees Fahrenheit or higher as a possible neutropenic emergency. Remember also that vincristine is given intravenously only and is fatal if administered intrathecally.

Special Populations and Safety

Name three Beers Criteria concerns in older adults.

Benzodiazepines and other sedative hypnotics because of falls and delirium, first-generation antihistamines such as diphenhydramine and other strong anticholinergics because of confusion and urinary retention, and NSAIDs because of gastrointestinal bleeding and kidney injury. Reduced renal clearance and lower albumin also amplify drug effect.

What replaced the lettered pregnancy risk categories, and name common teratogens?

The Pregnancy and Lactation Labeling Rule, which uses narrative risk summaries. Teratogenic or contraindicated agents include warfarin, ACE inhibitors and ARBs, isotretinoin, methotrexate, statins, tetracyclines, and valproate.

What is the correct sequence after discovering a medication error?

Assess and stabilize the client first, provide indicated interventions, notify the provider, document the facts objectively in the medical record, and complete the occurrence report. The occurrence report is a quality improvement document and is not placed in or referenced in the chart.

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