1. A 9-year-old receiving vincristine as part of an acute lymphoblastic leukemia regimen develops oropharyngeal candidiasis, and the covering team plans to start oral itraconazole. The oncology pharmacist is asked to review the interaction before the antifungal is started. Which action is most appropriate?
A) Proceed with itraconazole and increase the vincristine dose to maintain efficacy
B) Proceed with itraconazole and add prophylactic granulocyte colony-stimulating factor to prevent the expected toxicity
C) Avoid the azole if possible and choose a non-CYP3A4-inhibiting antifungal strategy, because itraconazole inhibits CYP3A4 and will increase vincristine exposure and neurotoxicity risk
D) Proceed unchanged, because vincristine is renally eliminated and does not interact with azoles
E) Stop vincristine permanently, because any azole exposure causes irreversible myelosuppression
ANSWER: C
Rationale:
Vincristine is metabolized by CYP3A4 and is a P-glycoprotein substrate. Itraconazole is a strong CYP3A4 inhibitor, so co-administration reduces vincristine metabolism, increases exposure, and raises the risk of severe neurotoxicity, an interaction of particular concern in pediatric leukemia regimens. The appropriate step is to avoid the interacting azole where possible and select an antifungal strategy that does not strongly inhibit CYP3A4, rather than continuing the combination.
Option A: Option A is incorrect: increasing the vincristine dose while inhibiting its metabolism compounds the exposure increase and the neurotoxicity risk.
Option B: Option B is incorrect: the dominant toxicity from increased vincristine exposure is neuropathy, which granulocyte colony-stimulating factor does not prevent.
Option D: Option D is incorrect: vincristine is hepatically metabolized by CYP3A4, not renally eliminated, so the interaction is real.
Option E: Option E is incorrect: vincristine's interaction with azoles raises neurotoxicity through CYP3A4 inhibition, not irreversible myelosuppression, and permanent discontinuation is not the correct framing.
2. A 54-year-old man on a vincristine-containing lymphoma regimen reports several weeks of worsening constipation and new tingling in both feet. On examination, his ankle deep tendon reflexes are absent and he has mild distal sensory loss, but strength is preserved. Which interpretation and next step is most appropriate?
A) These are signs of cumulative vincristine neurotoxicity, and the vincristine dose should be reduced or delayed with continued serial neurologic monitoring
B) These findings indicate vincristine-induced myelosuppression, and the next step is to check an absolute neutrophil count and hold for neutropenia
C) These findings are unrelated to vincristine and warrant only reassurance with no change to therapy
D) These findings indicate spinal cord compression and mandate immediate high-dose corticosteroids regardless of the chemotherapy
E) These findings reflect a drug allergy and require permanent discontinuation of all chemotherapy
ANSWER: A
Rationale:
Loss of ankle deep tendon reflexes with distal paresthesias and autonomic constipation is the classic early, length-dependent presentation of cumulative vincristine neurotoxicity, the drug's dose-limiting toxicity. Because the neuropathy is cumulative and only partially reversible, the appropriate response is dose reduction or delay with continued serial neurologic examination before each cycle, detecting progression early rather than waiting for motor deficits.
Option B: Option B is incorrect: vincristine's dose-limiting toxicity is neuropathy, not myelosuppression, and these neurologic findings are not a neutropenia signal.
Option C: Option C is incorrect: these are recognizable vincristine neurotoxicity findings that require dose modification, not reassurance alone.
Option D: Option D is incorrect: the symmetric distal sensory pattern with lost reflexes fits drug neuropathy rather than cord compression, which would typically produce a sensory level, weakness, and upper motor neuron signs.
Option E: Option E is incorrect: this is a dose-related toxicity managed by modification and monitoring, not an allergic reaction requiring permanent cessation of all chemotherapy.
3. A 38-year-old woman receiving vincristine is found to have a serum sodium of 124 mEq/L. She is clinically euvolemic, with low serum osmolality, urine osmolality of 320 mOsm/kg, and a urine sodium of 50 mEq/L. She has mild headache but no seizures. Which management approach is most appropriate?
A) Administer normal saline boluses for presumed hypovolemia
B) Begin a loop diuretic to promote free water retention
C) Give a large fixed dose of intravenous hypertonic saline as rapidly as possible to normalize sodium within hours
D) Institute fluid restriction for vincristine-associated SIADH, reserving carefully controlled hypertonic saline for severe or symptomatic hyponatremia
E) Increase the vincristine dose, since the hyponatremia indicates inadequate drug effect
ANSWER: D
Rationale:
Euvolemic hyponatremia with low serum osmolality and inappropriately concentrated urine is the syndrome of inappropriate antidiuretic hormone secretion (SIADH), a recognized vincristine effect from disruption of the hypothalamic-neurohypophyseal axis. With mild symptoms, the appropriate management is fluid restriction, reserving carefully controlled hypertonic saline for severe or clearly symptomatic hyponatremia, with attention to a safe rate of correction.
Option A: Option A is incorrect: this patient is euvolemic with SIADH, and saline loading does not correct, and may worsen, the dilutional hyponatremia.
Option B: Option B is incorrect: a loop diuretic does not promote free water retention; the issue is water excess, not solute excess to be retained.
Option C: Option C is incorrect: rapid, large-volume hypertonic correction risks overcorrection; correction must be controlled and rate-limited.
Option E: Option E is incorrect: SIADH is an adverse effect, not a marker of inadequate drug effect, so increasing vincristine is inappropriate.
4. A 61-year-old woman with ovarian cancer is receiving her first dose of conventional paclitaxel. She received the standard premedication. About 6 minutes into the infusion she develops facial flushing, dyspnea with audible wheezing, and a blood pressure drop to 84/50 mmHg. Which immediate action is most appropriate?
A) Slow the infusion slightly but continue, since premedicated patients cannot have a true reaction
B) Stop the paclitaxel infusion immediately and provide supportive care (airway support, fluids, antihistamines, and corticosteroids, with epinephrine if severe), recognizing a Cremophor EL anaphylactoid reaction
C) Switch the patient to docetaxel mid-infusion to bypass the reaction
D) Administer a CYP2C8 inhibitor to slow paclitaxel metabolism and blunt the reaction
E) Continue the infusion and order beta-III tubulin testing to determine the cause
ANSWER: B
Rationale:
This is the classic presentation of a Cremophor EL anaphylactoid reaction: flushing, bronchospasm, and hypotension within the first minutes of a conventional paclitaxel infusion. The reaction is non-IgE-mediated and can occur despite premedication. The immediate action is to stop the infusion and provide supportive care, escalating to epinephrine for severe reactions; many patients can be rechallenged at a slower rate after stabilization and additional antihistamine and corticosteroid.
Option A: Option A is incorrect: premedication reduces but does not eliminate reactions, and continuing through hypotension and bronchospasm is unsafe.
Option C: Option C is incorrect: switching agents mid-infusion during an acute reaction is not appropriate management; stabilize the patient first.
Option D: Option D is incorrect: the reaction is a vehicle-mediated anaphylactoid event, not a problem of metabolism that a CYP2C8 inhibitor would address.
Option E: Option E is incorrect: the cause is already evident as a Cremophor anaphylactoid reaction, and continuing the infusion to pursue tubulin testing endangers the patient.
5. A 67-year-old man several cycles into docetaxel therapy (cumulative dose now above 400 mg/m squared) develops progressive lower-extremity edema, a small pleural effusion, and weight gain. His cardiac and renal evaluation is unremarkable, and a review of his treatment record shows the dexamethasone premedication was frequently shortened or omitted. Which explanation and corrective step is most appropriate?
A) This is anthracycline-type cardiotoxicity, and an echocardiogram with cardiology referral is the priority before any other step
B) This is Cremophor EL hypersensitivity, and the three-drug antihistamine premedication should be intensified
C) This is vincristine-type autonomic dysfunction unrelated to docetaxel
D) This is tumor lysis syndrome, and rasburicase should be started
E) This is docetaxel fluid retention from the polysorbate 80 vehicle, and ensuring adequate dexamethasone premedication (with attention to the cumulative dose) is the appropriate corrective measure
ANSWER: E
Rationale:
Docetaxel is formulated in polysorbate 80, which causes a cumulative fluid retention syndrome (edema, pleural effusions, ascites) that becomes a management challenge at higher cumulative doses. This syndrome is substantially attenuated by dexamethasone premedication, so a record of shortened or omitted dexamethasone fits both the presentation and the corrective step: ensure adequate corticosteroid premedication and account for the cumulative dose.
Option A: Option A is incorrect: docetaxel's vehicle-related fluid retention, not anthracycline cardiotoxicity, fits a normal cardiac and renal workup with this premedication history.
Option B: Option B is incorrect: the polysorbate 80 fluid retention syndrome is distinct from the Cremophor EL anaphylactoid reaction; intensifying antihistamines does not address fluid retention.
Option C: Option C is incorrect: this is a docetaxel vehicle effect, not vincristine autonomic dysfunction.
Option D: Option D is incorrect: the picture is fluid retention, not the metabolic derangements of tumor lysis syndrome.
6. During a peripheral intravenous infusion of vinblastine, the nurse notices swelling, the infusion slows, and the patient reports burning at the catheter site, consistent with extravasation of the vesicant. Which local management is most appropriate?
A) Stop the infusion, and manage with hyaluronidase infiltration to disperse the drug plus warm compress application
B) Apply ice packs continuously and keep the area cold, the same as for anthracycline extravasation
C) Flush the line briskly with additional fluid to push the drug into the tissue and dilute it
D) Take no action, because vinca alkaloids are not vesicants and do not injure tissue
E) Apply a tight compression wrap to localize the drug and prevent any dispersion
ANSWER: A
Rationale:
Vinca alkaloids are vesicants, and extravasation can cause severe local tissue necrosis. The recommended approach is to stop the infusion and manage with hyaluronidase infiltration, which disperses the extravasated drug, combined with warm compress application to promote dispersion and absorption. This warm-and-disperse strategy is the opposite of the cold-and-localize approach used for some other vesicants, a frequent point of confusion.
Option B: Option B is incorrect: cold/localize is the anthracycline strategy; for vinca alkaloids, warmth and dispersion are used.
Option C: Option C is incorrect: flushing more fluid into extravasated tissue worsens local exposure rather than helping.
Option D: Option D is incorrect: vinca alkaloids are vesicants and do cause necrosis, so inaction is unsafe.
Option E: Option E is incorrect: tight compression to localize the drug runs counter to the dispersion strategy appropriate for vinca alkaloid extravasation.
7. A patient scheduled for intrathecal methotrexate and intravenous vincristine on the same day is mistakenly given the vincristine by the intrathecal route. The error is recognized within the first hour, before symptoms develop. Which immediate management offers the only described chance of limiting the injury?
A) Administer intravenous calcium and observe, since the syndrome is usually self-limited
B) Give a single dose of intravenous corticosteroids and discharge with outpatient follow-up
C) Initiate emergent cerebrospinal fluid lavage (CSF exchange) with neurosurgical placement of a drain, combined with intrathecal fresh frozen plasma instillation, as the only described intervention with rare partial survivors
D) Begin systemic plasmapheresis as definitive therapy expected to fully reverse the injury
E) Provide reassurance, because intrathecal vincristine produces only a transient, fully reversible radiculopathy
ANSWER: C
Rationale:
Inadvertent intrathecal vinca alkaloid administration produces an ascending myeloencephalopathy that is nearly uniformly fatal, and the only intervention with rare partial survivors reported is immediate, aggressive cerebrospinal fluid (CSF) lavage through a neurosurgically placed drain, exchanging as much CSF as feasible, combined with intrathecal instillation of fresh frozen plasma (the plasma proteins bind the drug). Recognition within the first hour is exactly when this attempt is most worthwhile, alongside immediate neurosurgical involvement, even though complete recovery has not been documented.
Option A: Option A is incorrect: the syndrome is not self-limited; it is progressive and usually fatal without aggressive intervention.
Option B: Option B is incorrect: a single corticosteroid dose with discharge is grossly inadequate for this emergency.
Option D: Option D is incorrect: systemic plasmapheresis does not address drug already in the CSF and is not the described rescue.
Option E: Option E is incorrect: the injury is progressive and life-threatening, not a transient reversible radiculopathy.
8. A 72-year-old man with metastatic castration-resistant prostate cancer has progressed after docetaxel-based therapy. His oncologist plans a taxane that can overcome P-glycoprotein-mediated resistance. Which agent and supportive-care plan is most appropriate?
A) Re-treat with the same docetaxel regimen at a higher dose, since resistance can be overcome by dose escalation alone
B) Use cabazitaxel, which is a poor P-glycoprotein substrate and can act in P-gp-overexpressing cells, with primary granulocyte colony-stimulating factor prophylaxis because of its high febrile neutropenia rate
C) Switch to a vinca alkaloid given intrathecally to bypass systemic resistance
D) Begin ixabepilone with capecitabine despite a bilirubin of 2.0 mg/dL, since hepatic function does not affect this combination
E) Use conventional paclitaxel, which is unaffected by P-glycoprotein efflux
ANSWER: B
Rationale:
Cabazitaxel was developed specifically to overcome P-glycoprotein (P-gp)-mediated taxane resistance: it is a poor P-gp substrate and can reach cytotoxic intracellular concentrations in P-gp-overexpressing cells. It is approved for castration-resistant prostate cancer after prior docetaxel, where it improved survival versus mitoxantrone. Because cabazitaxel causes febrile neutropenia at a substantially higher rate than docetaxel, primary granulocyte colony-stimulating factor prophylaxis is recommended for all patients.
Option A: Option A is incorrect: re-treating with the same docetaxel regimen does not overcome P-gp resistance, and dose escalation alone is not the strategy.
Option C: Option C is incorrect: intrathecal vinca alkaloid administration is fatal and is never a route for systemic therapy.
Option D: Option D is incorrect: ixabepilone with capecitabine is contraindicated when bilirubin exceeds 1.5 times the upper limit of normal, so a bilirubin of 2.0 mg/dL is a contraindication, not a safe choice.
Option E: Option E is incorrect: conventional paclitaxel is a P-gp substrate and is effluxed by P-gp, so it is affected by this resistance mechanism.
9. A 58-year-old woman with metastatic breast cancer has progressed after anthracycline and taxane therapy. The team considers ixabepilone in combination with capecitabine. Her laboratory studies show AST 3 times the upper limit of normal and bilirubin 1.8 times the upper limit of normal. Which decision is most appropriate?
A) Proceed with ixabepilone plus capecitabine at full dose, since liver function does not affect this regimen
B) Proceed with ixabepilone plus capecitabine but simply add granulocyte colony-stimulating factor to offset any added risk
C) Proceed with the combination after a single dose of corticosteroid, which neutralizes the hepatic risk
D) Do not use ixabepilone with capecitabine in this patient, because hepatic impairment with AST or ALT above 2.5 times the upper limit of normal or bilirubin above 1.5 times the upper limit of normal is a contraindication to this combination owing to markedly increased toxic deaths
E) Substitute intrathecal ixabepilone to bypass hepatic metabolism
ANSWER: D
Rationale:
Hepatic impairment markedly increases ixabepilone exposure and toxicity. In combination with capecitabine, ixabepilone is contraindicated when AST or ALT exceeds 2.5 times the upper limit of normal, or bilirubin exceeds 1.5 times the upper limit of normal, because of markedly increased toxic deaths observed in hepatically impaired patients receiving this combination in clinical trials. This patient meets both thresholds, so the combination should not be used.
Option A: Option A is incorrect: hepatic function does affect this regimen, and the patient exceeds the contraindication thresholds.
Option B: Option B is incorrect: granulocyte colony-stimulating factor does not address the hepatic-impairment-related toxic death risk that defines the contraindication.
Option C: Option C is incorrect: a corticosteroid does not neutralize the hepatic contraindication.
Option E: Option E is incorrect: ixabepilone is given systemically; there is no intrathecal route, and intrathecal administration of microtubule agents is dangerous.
10. A patient with non-small cell lung cancer progresses on taxane-based therapy. Tumor profiling shows high beta-III tubulin expression. The oncologist wants to select a subsequent agent informed by this resistance mechanism. Which choice is best supported?
A) Re-challenge with the same taxane at a higher dose, since beta-III tubulin overexpression increases taxane binding
B) Add a P-glycoprotein inhibitor to the same taxane, since beta-III tubulin overexpression acts through P-gp efflux
C) Abandon all microtubule-targeting agents, since beta-III tubulin overexpression confers uniform resistance to the entire class
D) Continue the current taxane unchanged, since beta-III tubulin overexpression affects only the vinca alkaloids
E) Select an agent less affected by beta-III tubulin overexpression, such as a vinca alkaloid or ixabepilone
ANSWER: E
Rationale:
Beta-III tubulin is the isotype with the lowest taxane affinity; its overexpression lowers paclitaxel binding and yields more dynamic microtubules, producing taxane resistance associated with poor outcomes in non-small cell lung cancer. Because vinca alkaloids and ixabepilone are less affected by beta-III tubulin overexpression, selecting one of those agents is the rational, mechanism-informed next step.
Option A: Option A is incorrect: beta-III overexpression lowers taxane binding affinity, so re-challenge at higher dose is not supported.
Option B: Option B is incorrect: this is a tubulin-binding (target-level) mechanism, not P-gp efflux, so adding a P-gp inhibitor does not address it.
Option C: Option C is incorrect: the resistance is selective rather than uniform; other microtubule agents retain activity.
Option D: Option D is incorrect: it reverses the relationship, since beta-III overexpression principally reduces taxane efficacy while sparing vinca alkaloids.
11. An infusion nurse is preparing to administer conventional (Cremophor EL-based) paclitaxel and notices that the only administration set immediately available is standard polyvinyl chloride (PVC) tubing. What is the most appropriate action before starting the infusion?
A) Obtain a non-PVC administration set, because the Cremophor EL vehicle leaches DEHP plasticizer from PVC tubing at clinically significant concentrations
B) Proceed with the PVC tubing, since the vehicle does not interact with tubing materials
C) Proceed with PVC tubing but run the infusion faster to limit contact time, which makes plasticizer leaching irrelevant
D) Switch the order to nab-paclitaxel mid-preparation to justify using the PVC tubing on hand
E) Add an in-line corticosteroid to the PVC tubing to neutralize any leached plasticizer
ANSWER: A
Rationale:
Conventional paclitaxel must be infused through non-PVC tubing because its Cremophor EL (polyoxyethylated castor oil) vehicle leaches DEHP (di(2-ethylhexyl) phthalate) plasticizer from polyvinyl chloride tubing at clinically significant concentrations. The correct action is to obtain a non-PVC administration set before starting, the same vehicle-driven precaution that pairs with the hypersensitivity premedication for this formulation.
Option B: Option B is incorrect: the Cremophor EL vehicle does interact with PVC tubing by extracting DEHP, so the precaution is necessary.
Option C: Option C is incorrect: running faster does not make plasticizer leaching acceptable; a non-PVC set is required.
Option D: Option D is incorrect: changing the ordered drug to fit the available tubing is not appropriate; obtain the correct tubing for the drug ordered.
Option E: Option E is incorrect: an in-line corticosteroid does not neutralize leached plasticizer and does not address the requirement for non-PVC tubing.
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