(Cureus)—A 40-year-old woman with hx of HIV, coronary artery disease, peripheral vascular disease, and polysubstance abuse presented with critical limb ischemia of the right leg. The patient received a femoral artery stent, and apixaban 2.5 mg bid was started. The patient returned with low back pain 1 week postdischarge, and a CT scan demonstrated a large retroperitoneal hematoma.

Meds: clopidogrel, darunavir/cobicistat, abacavir/dolutegravir/lamivudine, atorvastatin, isosorbide dinitrate, and hydralazine.

Which drug combo could have caused the hematoma?
clopidogrel and atorvastatin
clopidogrel and darunavir/cobicistat
apixaban and abacavir/dolutegravir/lamivudine
apixaban and darunavir/cobicistat
You are correct. Cobicistat, a strong CYP3A4 inhibitor and P-glycoprotein (P-gp) inhibitor, may significantly increase the plasma level of apixaban; therefore, the apixaban dose should be decreased by 50%, or the combination should be avoided, if the patient is already on apixaban 2.5 mg bid. Furthermore, darunavir, a moderate CYP3A4 inhibitor and weak P-gp inhibitor, may also contribute to the inhibition of apixaban metabolism, leading to increased systemic exposure.

More info is available in the free, full-text Cureus article PDF at PubMed Central.

Source article: Ammar H, Govindu RR. A dangerous and unrecognized interaction of apixaban. Cureus. 2021;13(11):e19688. doi: 10.7759/cureus.19688.

Source image: Ammar and Govindu Cureus (2021) 13(11): e19688. DOI 10.7759/cureus.19688.
(Cancer Rep)—A 62-year-old woman with DM, dyslipidemia, HTN, renal impairment, and HR-positive, HER-2 negative metastatic breast cancer presented with a 1-wk hx of progressive dyspnea, intermittent epigastric pain, and nausea approximately 2mo after starting ribociclib. Admission labs: BUN 56 mg/dL, Cr 2.8 mg/dL, sodium 133 mEq/L, potassium 5.6 mEq/L, chloride 102 mEq/L, bicarbonate 6 mEq/L, CPK 715 U/L, glucose 217 mg/dL, lactate 13.7 mmol/L, pH 7.12, pCO2 20.8 mm Hg, Po2 66.8 mm Hg, anion gap 25.

The patient was diagnosed with severe lactic acidosis and acute respiratory failure.

Meds: metformin, glipizide, losartan, amlodipine, simvastatin, ribociclib, fulvestrant.

Which drug combo could have caused the lactic acidosis?
ribociclib and metformin
metformin and simvastatin
fulvestrant and losartan
amlodipine and glipizide
You are correct. Ribociclib inhibits the renal transporters OCT2 and MATE1, potentially increasing metformin levels and the risk of lactic acidosis. Use this combination with caution.

More info is available in the free, full-text Cancer Rep article at PubMed Central.

Source article: Lagampan C, Poovorawan N, Parinyanitikul N. Lactic acidosis, a potential toxicity from drug–drug interaction related to concomitant ribociclib and metformin in preexisting renal insufficiency: A case report. Cancer Rep (Hoboken). 2022;5:e1575. doi: 10.1002/cnr2.1575.
(epocrates)—The absorption of the oral antifungal itraconazole is sensitive to changes in gastric pH. For example, gastric acid suppressors such as H2-receptor antagonists and proton pump inhibitors commonly result in a decrease in itraconazole absorption, and hence a potential decrease in efficacy.

Which formulation of itraconazole has been linked w/ increased systemic exposure when co-administered w/ acid suppressors?
itraconazole 100-mg capsule
itraconazole 10-mg/mL solution
itraconazole 200-mg tablet
itraconazole 65-mg capsule
You are correct. The proton pump inhibitor omeprazole increased the systemic exposure of itraconazole 65-mg capsules (Tolsura) by 22% and increased its Cmax by 31%. Thus, monitoring for itraconazole-associated adverse reactions is recommended, and itraconazole dose reduction may be necessary.

Source: Tolsura [package insert]. Greenville, NC: Mayne Pharma; 2018.

Learn more about Tolsura in epocrates.
(BMJ)—A woman in her 80s had a persistent, mildly itchy lesion on her R chest x3y in an area frequently exposed to sun in the summer, when she’d usually wear vests. The lesion improved only slightly with topical steroids and antifungals. Exam: annular red plaque with crusts and scales. Potassium hydroxide test negative. What’s the dx?
Porokeratosis of Mibelli
Basal cell carcinoma
Chronic eczema
Bowen disease
Tinea corporis
You are correct. Bowen disease was confirmed by bx. This lesion typically manifests as an asymptomatic, sharply demarcated, erythematous patch/plaque with crusts and scales on areas exposed to sunlight. It may progress to invasive squamous cell carcinoma. Risk factors include skin tones of Fitzpatrick types I and II, older age, chronic sun exposure, hx of contact with arsenic, skin trauma, burns, and other chronic scars. The patient declined surgical excision or other further tx.

BMJ 2022;379:e071572
(BMJ)—A nonsmoking man in his 30s had asymptomatic tongue lesions found during a derm eval. PMHx: psoriasis, no alcohol misuse. Exam: thick, scaly red plaques on scalp, back, and limbs. Tongue: reddish area with absent papillae; branching fissures. What’s the dx?
Erythematous candidiasis
Leukoplakia
Erythroplakia
Lichen planus
Geographic tongue
You are correct. Geographic tongue, also known as benign migratory glossitis, is characterized by 1 or more areas of atrophy of the filiform papillae. The areas change in shape and location over time (migration pattern). Most cases are asymptomatic and can persist for decades without the lesion being noticed. Geographic tongue may be seen in people with psoriasis and may improve with systemic tx for psoriatic skin lesions.

Erythematous candidiasis on the tongue manifests as painful red lesions in the center of the dorsum of the tongue and may be seen in patients with HIV. Lichen planus presents as white patches with a lacy surface and pain. Erythroplakia produces well-defined red plaques/patches that have a velvety texture and bleed easily, and leukoplakia as well-defined white plaques/patches on the ventrolateral surface of the tongue.

The patient was started on oral apremilast and topical calcipotriol/betamethasone dipropionate for skin psoriatic lesions. At 1-year follow-up, the skin plaques and glossal lesions had disappeared.

BMJ 2022;379:e071453