Delirium following a switch from cimetidine to famotidine

Delirium and its Pharmacological Causes in Older People, Part Two

Delirium is a syndrome that can arise from many causes or underlying conditions, and though it has been reported in younger patients, it is more prevalent in older people, though it can occur in other age groups as well. Identifying delirium is challenging in older people because of the coexistence of underlying dementia or depression, which may further complicate the presentation. Drug-induced delirium is one of the major causes of delirium, and evaluation of this potential cause or contribution is an important component of the evaluation process, since it can lead to poor patient outcomes. Part one of this three part series reviewed the epidemiology, pathophysiology, evaluation, diagnostic process, and causes of delirium in older people, with a focus on the pharmacological causes. Part two of this series continues to review drugs and drug classes that can cause or contribute to delirium in older people.

Association of Histamine-2 Blockers and Proton-Pump Inhibitors With Delirium Development in Critically Ill Adults: A Retrospective Cohort Study

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OBJECTIVES:

Histamine-2 receptor antagonists are commonly administered for stress ulcer prophylaxis in critically ill adults and may be associated with delirium development. We aimed to determine differential associations of histamine-2 receptor antagonist or proton-pump inhibitor administration with delirium development in patients admitted to a medical ICU.

DESIGN:

Retrospective observational study using a deidentified database sourced from the University of North Carolina Health Care system. Participants were identified as having delirium utilizing an International Classification of Diseases-based algorithm. Associations among histamine-2 receptor antagonist, proton-pump inhibitor, or no medication administration and delirium were identified using relative risk. Multiple logistic regression was used to control for potential confounders including mechanical ventilation and age.

SETTING:

Academic tertiary care medical ICU in the United States.

PATIENTS:

Adults admitted to the University of North Carolina medical ICU from January 2015 to December 2019, excluding those on concurrent histamine-2 receptor antagonists and proton-pump inhibitors in the same encounter.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

We identified 6,645 critically ill patients, of whom 29% (n = 1,899) received mechanical ventilation, 45% (n = 3,022) were 65 or older, and 22% (n = 1,487) died during their medical ICU encounter. Of the 6,645 patients, 31% (n = 2,057) received an histamine-2 receptor antagonist and no proton-pump inhibitors, 40% (n = 2,648) received a proton-pump inhibitor and no histamine-2 receptor antagonists, and 46% (n = 3,076) had delirium. The histamine-2 receptor antagonist group had a greater association with delirium than the proton-pump inhibitor group compared with controls receiving neither medication, after controlling for mechanical ventilation and age (risk ratio, 1.36; 1.25–1.47; p < 0.001) and (risk ratio, 1.15; 1.07–1.24; p < 0.001, respectively).

CONCLUSIONS:

Histamine-2 receptor antagonists are more strongly associated with increased delirium than proton-pump inhibitors. Prospective studies are necessary to further elucidate this association and to determine if replacement of histamine-2 receptor antagonists with proton-pump inhibitors in ICUs decreases the burden of delirium in critically ill patients.

A Rare Case of Famotidine-Induced Delirium in a Peritoneal Dialysis Patient

H2 receptor antagonists are commonly employed to manage gastro-esophageal reflux and peptic ulcer diseases with a very low incidence of side effects. Herein, we report an extremely rare incidence of famotidine-induced acute confusion in a patient with end-stage renal failure. We also discuss the pharmacokinetic properties of famotidine and its interplay with compromised renal function to result in neuropsychiatric manifestations, highlighting the importance of dosage adjustment in individuals with renal insufficiency.

Reduction in the rate of postoperative delirium by switching from famotidine to omeprazole in Japanese hepatectomized recipients

Background

Hepatectomy is a highly invasive procedure with a high probability of postoperative delirium. Treatment with antiulcer drugs is indispensable after hepatectomy for anastomotic ulcer management. The clinical pathway for hepatectomy was reviewed and the antiulcer drug used was switched from famotidine, a H₂-receptor antagonist, to omeprazole, a proton pump inhibitor, owing to the pharmacist’s intervention.

Methods

Hepatectomized recipients over 65 years of age, except in the cases of laparoscopic surgery and intensive care unit entry, were treated with famotidine injections (10 patients) or omeprazole injections (11 patients), and the incidence rates and severity of delirium were compared between the famotidine and omeprazole groups. The delirium after hepatectomy was assessed using the Japanese version of the NEECHAM confusion scale.

Results

The incidence rates of delirium were 90% in the famotidine group and 27.3% in the omeprazole group. Four out of 9 recipients in the famotidine group were injected with haloperidol to treat for delirium, but no recipients needed this treatment in the omeprazole group.

Conclusions

Compared with famotidine, the use of omeprazole was found to be effective in reducing the incidence rate and severity of postoperative delirium in patients undergoing hepatectomy. Pharmacists should actively strive to mitigate the risks of delirium.

Effect of famotidine in combination with antiepileptic drugs on locomotor activity in mice

Histamine type 2 receptor antagonists are one of the most commonly used agents to treat peptic ulcer disease. Since patients with epilepsy may have many comorbidities, the aim of this study was to investigate the influence of one of the strongest second generation histamine type 2 receptor antagonist, famotidine, on the exploratory and spontaneous activity in mice after 1 or 7 days treatment. Additionally, the interaction between famotidine and antiepileptics: carbamazepine, phenytoin, phenobarbital or valproate and their effect on animals activity was also evaluated. Locomotor activity was monitored electronically using a Digiscan analyzer in relation to ambulatory and rearing activities, as well as total distance travelled by animals during 15 minute periods. Results of our study indicate that famotidine administered alone did not modulate three variables of exploratory motor activity (horizontal activity, total distance and vertical activity) in mice. On the other hand, famotidine co-administered with valproate (1 day) or phenobarbital (1 day or 7 days) worsened vertical activity in mice in exploratory time. Similarly, impairment in horizontal activity in mice was observed when famotidine was given with phenobarbital (1 or 7 days). An increase in total distance in mice after famotidine alone or in combination with tested antiepileptic drugs was also shown. Moreover, famotidine alone or together with antiepileptic agents significantly impaired spontaneous locomotor activity in mice. The presented results show that famotidine administration to patients with epilepsy should be considered as potentially hazardous.

Heparin-Induced Thrombocytopenia—Delayed Onset Neurotoxicity with a Fluoroquinolone Anaphylaxis with Ondansetron Delirium Associated with H2-Receptor Antagonists Topiramate-Induced Depression

The purpose of this feature is to heighten awareness of specific adverse drug reactions (ADRs), to discuss methods of prevention, and to promote reporting of ADRs to the FDA's medWatch program (1-800-FDA-1088). If you have reported an interesting preventable ADR to medWatch, please consider sharing the account with our readers.

Liver tissue concentrations of levofloxacin after single intravenous administration of 500 mg for antibiotic prophylaxis in liver surgery

High concentrations of levofloxacin in soft tissues and body fluids, including gallbladder and bile, have been repeatedly reported, but no study on its penetration into human liver tissue after single-shot application has yet been published. Levofloxacin 500 mg was administered intravenously to 28 patients scheduled for liver resection. Blood samples were taken after the end of infusion and at the time of liver resection; concomitantly, a tissue specimen was also obtained. Serum concentrations (mean+/-standard deviation) 10 min after the end of infusion were 6.59+/-1.72 microg/mL and decreased only slightly throughout the operation. At the time of liver resection, levofloxacin concentrations in liver tissue were 18.14+/-5.44 microg/g with corresponding serum concentrations of 4.84+/-1.37 microg/mL. The tissue/serum ratio (3.72+/-0.73 at the time of resection) was nearly constant over the sampling period ranging from 0.4 h to 3.8 h after the end of infusion, indicating a fast distribution of levofloxacin into the liver tissue. The tissue concentrations showed a significant correlation with serum concentrations and an inverse correlation with the grade of steatosis but not cirrhosis. Infectious post-operative complications were not observed. Levofloxacin penetrates into liver tissue exceptionally well and fast and is therefore a good candidate for antibiotic prophylaxis before invasive hepatobiliary procedures such as liver surgery as well as for treatment of biliary tract infections caused by levofloxacin-susceptible microorganisms.

Urinary concentrations and bactericidal activities of newer fluoroquinolones in healthy volunteers

Eleven healthy male subjects participated in a crossover study to compare the urine concentrations and bactericidal activities of newer fluoroquinolones against common uropathogens. Each volunteer received a single oral dose of gatifloxacin (400 mg), levofloxacin (250 mg), moxifloxacin (400 mg) and trovafloxacin (200 mg), and a urine sample was obtained at 2, 6, 12 and 24 h after the dose. Urine concentrations were highest with gatifloxacin and levofloxacin and lowest with trovafloxacin. Each drug concentration was studied against a levofloxacin susceptible and moderately-susceptible strain of Escherichia coli (minimal inhibitory concentration, MICs: 0.125 and 4 mg/l), K. pneumoniae (MICs: 0.125 and 4 mg/l), Pseudomonas aeruginosa (MICs: 0.5 and 4 mg/l) and Enterococcus faecalis (MICs: 0.25 and 4 mg/l). The duration of urine bactericidal activity (UBA) was based upon the median bactericidal titre at each time period. Both gatifloxacin and levofloxacin exhibited prolonged (> or = 6 h) UBA against all of the study isolates. Moxifloxacin exhibited prolonged UBA against both isolates of E. coli, K. pneumoniae and E. faecalis but not against either strain of P. aeruginosa. Prolonged UBA was not observed for trovafloxacin against the moderately-susceptible strains with the exception of E. faecalis. Furthermore, UBA was not observed for trovafloxacin against the susceptible strain of P. aeruginosa. Although these newer fluoroquinolones exhibited similar in vitro activity against these uropathogens, only those compounds with the highest urinary concentrations (gatifloxacin and levofloxacin) produced prolonged UBA against both strains of P. aeruginosa. The findings from this study suggest that both microbiological activity and urinary concentrations are important parameters to consider when choosing a fluoroquinolone for empirical treatment of urinary tract infections (UTIs).

Fluoroquinolones for the treatment of outpatient community-acquired pneumonia

The increasing prevalence of beta-lactam and macrolide resistance in bacteria that cause respiratory infections has underscored the need for effective antimicrobial agents. The broad spectrum, excellent oral bioavailability, and once-daily dosing of fluoroquinolones contributed to the introduction of several new agents in the past decade. This class is among the world's most used antimicrobial therapies in community and hospital settings. Fluoroquinolones are generally well tolerated, but safety profiles differ widely among agents. Knowledge of in vitro activity, local microbiologic susceptibility and resistance patterns, adverse effects, and potential drug interactions should influence the selection of the best agent for individual patients. This overview of the fluoroquinolones directs particular attention to use in community-acquired pneumonia and safety.