Fluoroquinolone-Associated Dysglycemias: A Tale of Two Toxicities

Pharmacokinetics-pharmacodynamics, computer decision support technologies, and antimicrobial stewardship: the compass and rudder

The first guidelines for conducting antimicrobial stewardship in the hospitalized setting were published in 2007. These guidelines recommend that stewardship programs employ the science of pharmacokinetics-pharmacodynamics (PK-PD) as well as adopting computerized decision support technologies when possible. The United States Food and Drug Administration have adopted PK-PD as a cornerstone in the evaluation of antimicrobial agents during clinical development. The core principles of PK-PD center around describing the relationship between drug exposure indexed to the susceptibility of the infecting bacterial pathogen and patient response. Using such relationships with population pharmacokinetic models and simulation, rational drug and dosing regimens can be selected. But because PK-PD modeling and simulation programs are generally absent in clinical practice, systematic application of this science is missing. Herein we explain advances in technology that allow clinicians to apply PK-PD to optimize the agents and dosing regimens selected for the treatment of hospitalized patients with infection.

Life-threatening metabolic coma caused by levofloxacin

Patients with diabetes mellitus are often susceptible to hypoglycemic episodes while on therapy. Most of these are attributed to inappropriate dosing of hypoglycemic agents, dietary indiscretion, or acute illness. Medications being used concomitantly should be reviewed closely when the etiology of hypoglycemia is unclear. A fifty-six-year-old woman with a history of diabetes mellitus (on metformin monotherapy) was found unresponsive at home. Her fingerstick glucose was 15 mg/dL for which she received 50% dextrose intravenously. The patient never had any previous documented hypoglycemic episodes. She had recently been diagnosed with pneumonia and was prescribed oral levofloxacin therapy. The patient had taken 4 doses of levofloxacin before the onset of hypoglycemia. These episodes recurred over the next 2 days needing close intensive care unit monitoring, dextrose infusion, and glucagon administration. Basic blood/urine investigations, cortisol and thyroid profile were normal except for low blood glucose and renal insufficiency (serum creatinine 1.4 mg/dL and creatinine clearance 42 mL/min). HbA1c was 6.8% (4.4%-6.4%), insulin 51.3 μU/mL (2.6-24.9 μU/mL), IGF-1 301 ng/mL (27-223 ng/mL), and C peptide 9.3 ng/mL (0.8-3.5 ng/mL). These levels were elevated but were deemed nondiagnostic because of fluctuating glucose values after glucagon administration. A blood screen for sulfonylureas and metaglinides was negative. A seventy-two-hour fast was performed to rule out hyperinsulinemic hypoglycemic syndromes; however, blood glucose values remained consistently above 120 mg/dL during this period. Thus, after exclusion of other causes, we utilized the adverse drug reaction probability scale and concluded that hypoglycemia was probably related to recent use of levofloxacin.

Glimepiride-Induced Hypoglycemia with Ciprofloxacin, Metronidazole, and Acute Kidney Injury

A 79-year-old white male presented to the emergency room with altered mental status and a blood glucose of 28 mg/dL. He was taking glimepiride 1 mg by mouth daily prior to admission and had recently been prescribed ciprofloxacin and metronidazole for diverticulitis. The patient was also found to have acute-on-chronic renal failure upon presentation. Escalated dextrose infusion with repeated doses of D50W and glucagon failed to sustain his blood glucose, which remained in the range of 30 to 50 mg/dL. Salvage treatment with intravenous octreotide was implemented successfully; only one dose of D50W was required after octreotide initiation and blood glucose normalized within several hours. In the presence of this patient's complex medication therapy, we explore the contributing causes of hypoglycemia. Fluoroquinolones are widely associated with dysglycemias, particularly in diabetic patients receiving hypoglycemic agents. Similarly, renal insufficiency has been implicated to precipitate hypoglycemia with sulfonylureas, with dosage adjustment being required almost class-wide. We also recognize a theoretical drug interaction mediated by metronidazole-induced CYP 2C9 inhibition of glimepiride metabolism. Sulfonylurea-induced hypoglycemia can be serious and refractory to traditional therapy and can be exacerbated by multiple factors, such as drug interactions or impaired renal function. In the era of complex medication therapy for patient populations with multiple disease states, we present a severe episode of glimepiride-induced hypoglycemia with multiple causative factors.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.

An overview of harms associated with beta-lactam antimicrobials: where do the carbapenems fit in?

The US Institute of Medicine's focus on patient safety has motivated hospital administrators to facilitate a culture of safety. As a result, subcommittees of the pharmacy and therapeutics committee have emerged in many hospitals to focus on adverse events and patient safety. Antimicrobial harms have gained the attention of practicing clinicians and hospital formulary committees, because they top the list of drugs that are associated with adverse events and because of certain serious harms that have ultimately led to the withdrawal of some antimicrobial agents. In the near future, several antimicrobials in the late phase of development will become available for clinical use (ceftobiprole, ceftaroline, and telavancin), and others (doripenem and dalbavancin) have recently joined the armamentarium. Because new antimicrobials will become part of the treatment armamentarium, it is important to discuss our current understanding of antimicrobial harms in general. Although not thought of as traditional adverse events, Clostridium difficile infection and development of resistance during therapy are adverse events that occur as a result of antimicrobial exposure and therefore are discussed. In addition, a distillation of our current understanding of β-lactam specific adverse events will be provided. Finally, new methods of administration are being evaluated that may influence peak concentration-related antimicrobial adverse events.

Antimicrobial-associated QT interval prolongation: pointes of interest

Until recently, cardiac toxicity manifesting in the form of arrhythmias related to QT interval prolongation was uncommonly appreciated within the antimicrobial class of drugs, but it was well described among antiarrhythmic agents. Antimicrobials that are associated with QT prolongation include the macrolides/ketolides, certain fluoroquinolones and antimalarials, pentamidine, and the azole antifungals. Although, in most cases, mild delays in ventricular repolarization caused by these drugs are clinically unnoticeable, they may serve to amplify the risk for torsades de pointes (TdP) when prescribed in the setting of other risk factors. Conditions or variables that influence proarrhythmic risk include sex, age, electrolyte derangements, structural heart disease, pharmacokinetic/pharmacodynamic interactions, and genetic predisposition. It is important that clinicians be knowledgeable about drugs with QT liability, as well as the risk factors that increase the probability of TdP. Additionally, because TdP remains a difficult-to-measure adverse event, we must rely upon multiple data sources to determine the risk versus the benefit for newly approved drugs.

Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this new feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest will be abstracted monthly regarding a broad scope of topics.