Ceftazidime Plasma Concentrations and Neurotoxicity: The Importance of Therapeutic Drug Monitoring in Patients Undergoing Different Modalities of Renal Replacement Therapy. A Grand Round

Ceftazidime-related neurotoxicity in a patient with renal impairment: a case report and literature review

PURPOSE

We present the case of a 67-year-old woman with severely reduced renal clearance suffering from ceftazidime-induced encephalopathy. Subsequently, we search the literature to review and describe the neurotoxicity of ceftazidime.

METHODS

A search string was developed to search PubMed for relevant cases from which relevant information was extracted. Using the collected data a ROC analysis was performed in R to determine a neurotoxicity threshold.

RESULTS

Our patient suffered from progressive loss of consciousness and myoclonic seizures, with improvements noted a few days after discontinuation of treatment. The dose was not appropriately reduced to take into account her reduced renal function. The highest ceftazidime concentration recorded was 234.9 mg/mL. Using the Naranjo score we found a probable relationship between our patient's encephalopathy and ceftazidime administration. In the literature we found a total of 32 similar cases, most of which also had some form of renal impairment. Using our collected data and ceftazidime concentrations provided in the literature, a ROC analysis provided a neurotoxicity threshold of 78 mg/L for ceftazidime neurotoxicity.

CONCLUSION

Ceftazidime-related neurotoxicity is a known issue, especially in patients with severe renal impairment. Yet no concrete toxicity threshold has been reported so far. We propose the first toxicity threshold for ceftazidime of 78 mg/L. Future prospective studies are needed to validate and optimize the neurotoxicity threshold as upper limit for ceftazidime therapeutic drug monitoring.

Antibiotic-Drug Interactions in the Intensive Care Unit: A Literature Review

Interactions between drugs are a common problem in Intensive Care Unit patients, as they mainly have a critical condition that often demands the administration of multiple drugs simultaneously. Antibiotics are among the most frequently used medications, as infectious diseases are often observed in ICU patients. In this review, the most important antibiotic-drug interactions, based on the pharmacokinetic and pharmacodynamic mechanisms, were gathered together and described. In particular, some of the most important interactions with main groups of antibacterial drugs were observed in patients simultaneously prescribed oral anticoagulants, NSAIDs, loop diuretics, and valproic acid. As a result, the activity of drugs can be increased or decreased, as dosage modification might be necessary. It should be noted that these crucial interactions can help predict and avoid negative consequences, leading to better patient recovery. Moreover, since there are other factors, such as fluid therapy or albumins, which may also modify the effectiveness of antibacterial therapy, it is important for anaesthesiologists to be aware of them.