Clark, Sarah L.

AbstractApixaban is a widely used direct oral anticoagulant that is recommended over warfarin therapy for many clinical indications. In patients with atrial fibrillation, dose reductions are recommended for patients with advanced age (≥80 years), low weight (≤60 kg) or elevated serum creatinine (≥1.5 mg/dL), but there is no routine laboratory monitoring necessary for long term‐use. Furthermore, apixaban dose reductions due to renal dysfunction are not recommended when treating acute venous thromboembolism. Apixaban‐calibrated anti‐Xa assays are readily available at some medical centres, and they may be of clinical utility in certain circumstances such as in patients with renal insufficiency, medication adherence assessment, periprocedural planning, extremes in body weight and advanced age. Here, we describe the case of an elderly patient with chronic kidney disease taking apixaban for acute pulmonary embolism. The patient had an unanticipated prolonged apixaban half‐life, with detectable apixaban‐calibrated anti‐Xa levels for >10 days after the last administered dose, which delayed a necessary surgical intervention by >1 week. This case is an example of appropriately using apixaban‐calibrated anti‐Xa levels to guide therapeutic decision making in perioperative planning.

AbstractBackgroundNimodipine improves outcomes following aneurysmal subarachnoid hemorrhage (aSAH) and current guidelines suggest that patients with aSAH receive nimodipine for 21 days. Patients with no difficulty swallowing will swallow the whole capsules or tablets; otherwise, nimodipine liquid must be drawn from capsules, tablets need to be crushed, or the commercially available liquid product be used to facilitate administration through an enteral feeding tube (FT). It is not clear whether these techniques are equivalent. The goal of the study was to determine if different nimodipine formulations and administration techniques were associated with the safety and effectiveness of nimodipine in aSAH.MethodsThis was a retrospective multicenter observational cohort study conducted in 21 hospitals across North America. Patients admitted with aSAH and received nimodipine by FT for ≥3 days were included. Patient demographics, disease severity, nimodipine administration, and study outcomes were collected. Safety end points included the prevalence of diarrhea and nimodipine dose reduction or discontinuation secondary to blood pressure reduction. Predictors of the study outcomes were analyzed using regression modeling.ResultsA total of 727 patients were included. Administration of nimodipine liquid product was independently associated with higher prevalence of diarrhea compared to other administration techniques/formulations (Odds ratio [OR] 2.28, 95% confidence interval [CI] 1.41–3.67, p‐value = 0.001, OR 2.76, 95% CI 1.37–5.55, p‐value = 0.005, for old and new commercially available formulations, respectively). Bedside withdrawal of liquid from nimodipine capsules prior to administration was significantly associated with higher prevalence of nimodipine dose reduction or discontinuation secondary to hypotension (OR 2.82, 95% CI 1.57–5.06, p‐value = 0.001). Tablet crushing and bedside withdrawal of liquid from capsules prior to administration were associated with increased odds of delayed cerebral ischemia (OR 6.66, 95% CI 3.48–12.74, p‐value <0.0001 and OR 3.92, 95% CI 2.05–7.52, p‐value <0.0001, respectively).ConclusionsOur findings suggest that enteral nimodipine formulations and administration techniques might not be equivalent. This could be attributed to excipient differences, inconsistency and inaccuracy in medication administration, and altered nimodipine bioavailability. Further studies are needed.

SummaryDespite phenobarbital (PB) being a key component in status epilepticus (SE) treatment algorithms for decades, it has fallen out of favor compared to newer nonsedating medications due to potential for respiratory suppression and prolonged sedation. We retrospectively analyzed all nonintubated patients with refractory SE treated with parenteral PB. Forty patients were identified as having received PB in the neurologic intensive care unit at Mayo Clinic over a 7‐year period through our pharmacy dispensing database. Patients who received PB for maintenance therapy, those replenishing subtherapeutic levels, those who were already intubated, and those receiving PB for a non‐SE indication were excluded. Clinical data, prior treatments, therapeutic response, and outcome were reviewed. Eight patients were identified. Ages ranged from 24 to 77 years (median = 64 years); all had focal SE, and none was comatose. Seizure activity improved acutely following PB administration in seven and stopped in six. Dosages ranged from 5 to 19.8 mg/kg (median = 10.1 mg/kg); none required intubation, and one received supplemental oxygen. Patients received a median of four antiepileptic drugs prior to PB. Median interval between first drug and PB was 23.5 hours. Glasgow Coma Scale score did not change following PB administration. One patient required intervention for hypotension. Moderate‐dose parenteral PB was effective in attaining seizure control in a significant proportion of noncomatose refractory SE patients. None required ventilatory support. PB dosages below those in recent guidelines may be sufficient to stop SE without clinically significant cardiopulmonary complications.

Zoledronic acid (ZA) administration has been associated with electrolyte abnormalities, including hypocalcemia, hypomagnesemia, hypokalemia, and hypophosphatemia. We describe a case of severe, refractory hypophosphatemia in a patient who received ZA for hypercalcemia of malignancy (HCM). Little data are available that describe the incidence or degree of severity of hypophosphatemia that can occur following ZA administration. In addition, no formal recommendations exist to guide monitoring for or management of electrolyte derangements in the setting of bisphosphonate use. Our patient required daily, high-dose phosphorus replacement beginning day 4 following ZA administration. The average daily dose of phosphorus, including both intravenous and enteral administration, was highest in the first 2 weeks after ZA, averaging 77 mmol/d days 4 through 15, and does not include sources of phosphorus from the patient’s nutrition support. Despite this high amount of supplementation, which was well beyond what meets normal daily requirements and the amount expected to treat “usual” hypophosphatemia, the patient did not achieve sustained normal serum phosphorus levels for over 30 days after ZA. ZA is a favorable option for treating HCM because of its longer duration of action, potent serum calcium-lowering effects, and favorable safety profile. The risk of hypophosphatemia with ZA use is reviewed.

Ezogabine is an antiepileptic medication approved in June 2011 by the US Food and Drug Administration (FDA) as an adjunctive treatment for partial seizures. Minimal drug interactions and a novel mechanism of action made ezogabine an appealing new treatment option. However, adverse effects reported during clinical trials and following drug approval have been alarming. A Risk Evaluation Mitigation Strategy (REMS) program has been established for urinary retention. A safety alert was published in April 2013 warning ezogabine may cause retinal pigment abnormalities and/or blue-gray discoloration, most notably on or near the lips, nail beds, sclera and conjunctiva with long-term use. In October 2013, the FDA announced a formal label change to ezogabine to include a black boxed warning emphasizing the previously reported warnings of eye and skin discoloration and permanent vision changes. Given the unknown nature of the pathophysiology, consequences and potential for reversibility of these effects, GlaxoSmithKline and the FDA have published recommendations for patients currently receiving ezogabine. Further data from published case reports and long-term safety trials in the future may lend additional insight into these concerning effects.