Direct Fаctоr Xа Inhibitоrs Rivаrоxaban (Xarelto) Apixaban (Eliquis) Edoxaban (Savaysa) Mechanism of Action Directly inhibit Factor Xa (free + clot-bound) Block conversion: prothrombin → thrombin ↓ fibrin clot formation Pharmacokinetics Oral agents Onset: ~2–4 hours Duration: ~12 hours (varies) Hepatic metabolism (CYP3A4: rivaroxaban, apixaban) P-gp substrate → drug interactions Renal excretion → dose adjust in renal impairment Contraindicated: pregnancy, severe renal dysfunction Rivaroxaban taken with food Pharmacodynamics No routine monitoring required Rapid anticoagulant effect Predictable dose-response Reversal agent: Andexanet alfa Indications VTE treatment and prevention (DVT, PE) Stroke prevention in non-valvular AFib ACS/IHD risk reduction (selected cases) Heparin-induced thrombocytopenia (HIT) alternative (no PF4 interaction) Adverse Effects Bleeding (rivaroxaban highest risk among Xa inhibitors) Epidural/spinal hematoma → boxed warning Thrombotic events if abruptly stopped → boxed warning Edoxaban: ↑ ischemic stroke risk in non-valvular AFib → boxed warning Contraindications & Interactions Liver dysfunction (rivaroxaban, apixaban contraindicated) Moderate–severe hepatic impairment (edoxaban contraindicated) Strong CYP3A4 + P-gp inhibitors/inducers alter levels Monitoring No routine coagulation monitoring required Assess renal function periodically Monitor for bleeding signs Question: A 72-year-old man with nonvalvular atrial fibrillation is being evaluated for long-term stroke prevention. His past medical history is significant for hypertension and chronic kidney disease. Laboratory studies show a creatinine clearance of 18 mL/min (normal: >90 mL/min). Liver function tests are within normal limits. He is started on an anticoagulant. Which of the following is the most appropriate anticoagulation therapy for this patient?
Fоlic аcid (fоlаte) [FA-8] OverviewGeneric / Trаde Names: Fоlic acid (Folate, Vitamin B9)Drug Class: Water-soluble vitaminPrototype Example: Folic acid (synthetic folate) Mechanism of ActionMain Target / Pathway: Converted to tetrahydrofolate (THF)Primary Effect: Essential cofactor in DNA synthesis (purine, thymidine formation)Link to Use: Supports rapid cell division (RBC production, embryogenesis) PharmacokineticsAbsorption / Distribution: Oral, IV, IM, SC; oral absorption ↓ with food and drug interactionsMetabolism / Elimination: Hepatic conversion to active metabolitesExcretion: Renal (urine)Half-life: Relatively short; dependent on body stores PharmacodynamicsOnset / Duration: Gradual hematologic response in deficiency statesTherapeutic Index: Wide (generally safe vitamin profile) IndicationsMain Uses: Folic acid deficiency states; megaloblastic anemia due to folate deficiencyOff-Label Concepts: Supplementation in increased demand states (e.g., pregnancy)Drug-associated prevention: Mitigates antifolate effects (e.g., methotrexate-related deficiency risk) Adverse EffectsCommon Effects: Mild gastrointestinal upset, malaiseSerious Reactions: Rare hypersensitivity reactionsMechanism-Based Effects: May mask vitamin B12 deficiency hematologic findings while neurologic injury progresses Contraindications Untreated vitamin B12 deficiency (relative concern due to masking risk) Interactions Antifolate drugs (e.g., methotrexate) reduce folate availability; absorption reduced by some drugs and food interactions Question: A 58-year-old man presents to clinic for evaluation of fatigue and intermittent paresthesias in his feet. Laboratory studies show macrocytic anemia. He is found to have dietary folate deficiency and is started on folic acid supplementation. After several weeks of treatment, his hemoglobin improves; however, he later develops worsening gait instability and persistent numbness in his lower extremities. Which of the following is the most important potential complication of folic acid therapy in this patient?
IRON REPLACEMENT THERAPY Overview Orаl Ferrоus sulfаte (Ferоsul) Ferrоus gluconаte (Ferate) Ferrous fumarate (Ferretts) Ferrous bisglycinate Ferric citrate (Auryxia) Ferric maltol (Accrufer) Polysaccharide-iron complex (NovaFerrum) IV Iron dextran (CosmoFer) Ferumoxytol (Feraheme) Ferric carboxymaltose (Injectafer) Ferric derisomaltose (Monoferric) Iron sucrose (Venofer) Ferric gluconate (Ferrlecit) Mechanism of Action Replaces elemental iron → restores hemoglobin, myoglobin, and iron stores (ferritin, transferrin)IV iron bypasses GI absorptionFerric (Fe3+) → reduced to ferrous (Fe2+) for utilizationCorrects iron deficiency anemia and replenishes depleted iron stores Pharmacokinetics Oral: absorption in duodenum; requires acidic environmentIV: direct systemic iron deliveryMetabolism: stored as ferritin or bound to transferrinElimination: minimal urinary excretion (iron is conserved)Iron dextran: long tissue retention Pharmacodynamics Hgb rise in ~1–2 weeksFull correction: ~6–8 weeksRepletion of iron stores: up to 6 monthsTherapeutic IndexNarrow; risk of iron overload Indications Iron deficiency anemia (with or without anemia)Prevention in pregnancyErythropoietin (EPO)-associated anemiaIV iron: CKD, heavy uterine bleeding, malabsorption, intolerance to oral ironOff-Label ConceptsAnemia in chronic disease states when iron deficiency coexists Adverse Effects Common Effects (oral)Nausea, vomiting, constipation/diarrhea, epigastric painMetallic tasteDark stoolsTooth staining (liquid forms)Serious ReactionsIron overload → organ toxicity (liver, heart, pancreas) IV: hypersensitivity, anaphylaxis (esp. iron dextran, ferumoxytol)Hypotension, tachycardia, dizzinessMechanism-Based EffectsFree iron → oxidative stress, GI irritation Contraindications Iron overload states (hemochromatosis)Severe ongoing bleeding without controlSevere renal disease (deferoxamine contraindication noted)Caution: IBD, gastric bypass Interactions ↓ Absorption: tetracyclines, fluoroquinolones, levothyroxineAntacids, H2 blockers, PPIs ↓ absorptionImproved absorption with vitamin C / acidic environment Question: A 46-year-old woman is being treated for iron deficiency anemia with oral ferrous sulfate. She also takes levothyroxine for hypothyroidism and uses omeprazole for GERD. After 8 weeks of therapy, her hemoglobin has only minimally improved despite adherence to iron supplementation. Which of the following is the most likely reason for decreased iron efficacy in this patient?
Hydrоxyureа (hydrоxycаrbаmide) [Drоxia, Siklos] OverviewGeneric / Trade Names: Hydroxyurea (Hydroxycarbamide) / Droxia, SiklosDrug Class: Antimetabolite; ribonucleotide reductase inhibitor; cytotoxic agentPrototype Example: Hydroxyurea Mechanism of ActionInhibits ribonucleotide reductase → ↓ deoxyribonucleotide synthesis → ↓ DNA synthesisCell-cycle specific (S phase) → impairs DNA replication in rapidly dividing cellsIn sickle cell disease: induces γ-globin gene expression → ↑ HbF (α2γ2) → ↓ HbS polymerization → ↓ sicklingImproves RBC survival and reduces endothelial adhesion PharmacokineticsAbsorption: Oral administrationMetabolism: Hepatic metabolism (partial)Elimination: Renal excretionClinical note: exposure-dependent toxicity (myelosuppression risk increases with accumulation) PharmacodynamicsOnset: Delayed in SCD (weeks to months for HbF increase)Duration: Sustained with continuous useTherapeutic Index: Narrow (dose-limiting bone marrow suppression) IndicationsMyeloproliferative neoplasms (MPNs): polycythemia vera; also used in CML (adjunct/selected cases)Solid tumors (historical/limited use): melanomaSickle cell disease: reduces vaso-occlusive crises, hemolysis, and hospitalization; improves survivalNot used for acute sickle crises due to delayed onset Adverse EffectsCommon: myelosuppression (neutropenia, anemia, thrombocytopenia) — boxed warningSerious: secondary malignancies (including leukemia) — boxed warningMechanism-based: cytotoxic DNA synthesis inhibition → bone marrow toxicityOther: hyperpigmentation, skin rash, nail changes Contraindications Pregnancy; breastfeeding (teratogenic and cytotoxic risk) Interactions Additive myelosuppression with other cytotoxic or marrow-suppressing agents Question: A 28-year-old woman with a history of sickle cell disease presents for routine follow-up. She reports fewer pain crises since starting a new medication several months ago. Laboratory studies show improved hemoglobin levels and increased fetal hemoglobin (HbF). The medication works by increasing HbF production, which reduces hemoglobin S polymerization. Which of the following is the primary mechanism by which this medication decreases vaso-occlusive crises?