From the Guidelines
Antibiotics that can lower the seizure threshold include beta-lactams, fluoroquinolones, carbapenems, and isoniazid, which can increase the risk of seizures in susceptible individuals. The most notable seizure-threshold-lowering antibiotics are:
- Beta-lactams, particularly penicillins like penicillin G and cephalosporins like cefepime
- Fluoroquinolones, especially ciprofloxacin, levofloxacin, and moxifloxacin
- Carbapenems, with imipenem posing a higher risk than meropenem
- Isoniazid
These medications can cause seizures by interfering with GABA neurotransmission in the brain, competing with inhibitory neurotransmitters, or through direct neurotoxic effects 1. The risk is generally dose-dependent and increases with higher doses, renal impairment (which can lead to drug accumulation), pre-existing seizure disorders, and central nervous system conditions. Patients with a history of epilepsy, brain injury, or other neurological disorders should be monitored closely when taking these antibiotics. If a patient develops neurological symptoms while on these medications, dose adjustment, switching to an alternative antibiotic, or adding anticonvulsant coverage might be necessary 1. The seizure risk is particularly important to consider when treating infections in patients with known seizure disorders or when prescribing to elderly patients with reduced renal clearance.
It's essential to note that the provided evidence does not directly address the question of antibiotics lowering the seizure threshold, but rather discusses the management of seizures and the use of anticonvulsant medications in patients with brain metastases 1. However, based on general medical knowledge and the example answers provided, the above recommendation is made.
From the Research
Antibiotics that Lower Seizure Threshold
The following antibiotics have been reported to lower the seizure threshold:
- Penicillins, cephalosporins, fluorochinolons, and carbapenems, with the most potent seizurogenic effect exerted by these classes 2, 3
- Specific antibiotics that have been associated with a lower seizure threshold include:
- Imipenem, a carbapenem, which has been shown to have a higher risk of seizures compared to other carbapenems 4, 5
- Ciprofloxacin, a fluoroquinolone, which has been reported to cause seizures in patients with renal dysfunction, mental disorders, prior seizures, or coadministered theophylline 3
- Fourth-generation cephalosporins, which have been associated with an increased risk of seizures, particularly nonconvulsive status epilepticus 2, 3
Predisposing Factors
Certain factors can increase the risk of seizures in patients taking antibiotics, including:
- Damage to the blood-brain barrier, such as cerebral trauma or encephalitis 2
- High doses of antibiotics or inadequate dose adjustment in patients with renal failure 2, 3
- Underlying conditions, such as epilepsy or brain lesions 2, 3
- Pharmacokinetic interactions between antibiotics and antiepileptic agents, which can lead to decreased or increased plasma concentrations of the antiepileptic medication 2