There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
From the FDA Drug Label
The most common drug-related adverse experiences in patients treated with ertapenem for injection, including those who were switched to therapy with an oral antimicrobial, were ... Altered mental status‡5.13.43.32.5 ‡ Includes agitation, confusion, disorientation, decreased mental acuity, changed mental status, somnolence, stupor
Confusion is listed as part of altered mental status, which was reported in 5.1% of patients treated with ertapenem for injection 1. Therefore, ertapenem (Invanz) can cause confusion.
From the Research
Ertapenem-Induced Confusion
- Ertapenem (Invanz) has been associated with confusion and other neurotoxic effects in several studies 2, 3, 4, 5, 6.
- A case series of 10 patients with ertapenem neurotoxicity, mainly confusional states, reported that the majority of patients had a creatinine clearance (CrCl) < 50 mL/min/1.73m2 at some point during treatment and hypoalbuminaemia was always present when ertapenem treatment was started 2.
- Another study reported four cases of mental status changes and hallucinations in spinal cord injury patients attributed to ertapenem therapy, with onset of symptoms beginning between one and six days following initiation of ertapenem and resolving between two to 42 days following discontinuation 3.
- A literature review of 66 patients with ertapenem-induced neurotoxicity found that confusion was one of the most common symptoms, occurring in 22.7% of patients, and that neurotoxicity usually resolves with medication interruption, antiepileptic administration, or hemodialysis 5.
- A case report of a patient with end-stage renal disease on intermittent haemodialysis who developed ertapenem-induced neurotoxicity, including an acute confusional state and auditory and visual hallucinations, highlights the risk of potentially serious toxicity of the central nervous system in haemodialysis patients who receive the current recommended dose of ertapenem 6.
Risk Factors
- Advanced age, renal insufficiency, pre-existing neurological disease, and hypoalbuminemia are risk factors for ertapenem-induced neurotoxicity, including confusion 2, 3, 4, 5, 6.
- Patients with chronic kidney disease (CKD) are at increased risk of ertapenem-induced neurotoxicity due to the drug's renal excretion and increased half-life in CKD patients 6.
Clinical Characteristics
- The onset of symptoms of ertapenem-induced neurotoxicity, including confusion, can be insidious and go unnoticed, highlighting the importance of early suspicion and knowledge of confusional states to improve patient prognosis 2.
- Ertapenem-induced neurotoxicity can manifest as a range of symptoms, including epileptiform seizures, visual hallucinations, altered mental status, and confusion, with complete recovery usually occurring after discontinuation of the drug or other interventions 3, 4, 5, 6.