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Cefepime

Cefepime is a semi-synthetic, broad-spectrum, fourth-generation belonging to the class, primarily used for parenteral to treat serious bacterial infections caused by susceptible gram-positive and gram-negative pathogens. Its chemical structure features a quaternary ammonium at the 3-position, enhancing stability against beta-lactamases and providing expanded activity against , including Pseudomonas aeruginosa. Cefepime works by binding to , inhibiting bacterial synthesis, and leading to autolysis and . It is indicated for conditions such as (including those acquired in hospitals), complicated and uncomplicated urinary tract infections, skin and skin structure infections, intra-abdominal infections (often in combination with ), and for in patients with cancer. In 2024, the FDA approved a fixed-dose combination of cefepime with enmetazobactam for complicated urinary tract infections (including ). Approved by the U.S. in 1996 under the brand name Maxipime, cefepime is available as a salt in injectable forms (intravenous or intramuscular) at strengths of 500 mg, 1 g, and 2 g, typically reconstituted with L-arginine for stability. Dosing in adults generally ranges from 1 to 2 grams every 8 to 12 hours, adjusted for renal function to prevent accumulation, with pediatric doses based on weight (up to 50 mg/kg every 8 to 12 hours). Its spectrum includes many (e.g., , ), streptococci, and some activity against methicillin-susceptible , though it lacks coverage for anaerobes, enterococci, or methicillin-resistant staphylococci. Extended-infusion regimens (over 3-4 hours) have been explored to optimize against resistant pathogens, particularly in critical care settings. While generally well-tolerated, cefepime carries risks of reactions, particularly in patients with penicillin or allergies, and requires in those with known severe reactions. Notable adverse effects include gastrointestinal disturbances (e.g., ), rash, and injection-site reactions, but serious concerns involve such as , , and seizures, especially in elderly patients or those with impaired renal clearance. It may also promote Clostridium difficile-associated . Susceptibility testing is recommended prior to use to guide therapy and combat emerging resistance.

Medical uses

Indications

Cefepime is approved by the U.S. (FDA) for the treatment of several serious bacterial infections caused by susceptible strains of designated microorganisms. These include moderate to severe , uncomplicated and complicated urinary tract infections (including ), uncomplicated skin and skin structure infections, complicated intra-abdominal infections (in combination with ), and empiric therapy for febrile neutropenic patients. Off-label uses of cefepime include the treatment of infections caused by multidrug-resistant or extended-spectrum (ESBL)-producing , particularly when susceptibility testing confirms activity, often at higher doses or in combination regimens. Standard dosing regimens for adults with normal renal function ( clearance >60 mL/min) vary by infection severity and site: 0.5–2 g intravenously () or intramuscularly (IM) every 8–12 hours, with durations typically ranging from 7–10 days; for example, 2 g IV every 8 hours is recommended for due to P. aeruginosa or empiric therapy. In pediatric patients aged 2 months to 16 years with normal renal function, dosing is generally 50 mg/kg IV every 8–12 hours, not exceeding adult doses, with adjustments for specific infections like pneumonia caused by P. aeruginosa (50 mg/kg every 8 hours). The efficacy of cefepime in hospital-acquired infections is supported by clinical trials, including two multicenter, randomized studies demonstrating its effectiveness as monotherapy for , with success rates comparable to other . In , retrospective cohort analyses have shown cefepime to yield similar clinical outcomes, such as in-hospital mortality rates of approximately 10.5%, to , though subgroup differences may exist in high-risk populations like those requiring tube feeding.

Spectrum of activity

Cefepime exhibits activity against a variety of , including methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, and viridans group streptococci. For S. pneumoniae, (MIC) ranges typically fall between ≤0.007 and >8 μg/mL, reflecting susceptibility in penicillin-susceptible strains but higher values in resistant isolates. The antibiotic provides broad coverage against , particularly such as , , and , as well as . MIC ranges for E. coli span ≤0.007–128 μg/mL, while for P. aeruginosa, they range from 0.06 to >256 μg/mL, indicating variable susceptibility influenced by intrinsic resistance mechanisms. Cefepime demonstrates stability against many beta-lactamases, including AmpC and some extended-spectrum beta-lactamases (ESBLs), due to its low affinity for these enzymes, but it lacks activity against metallo-beta-lactamases and certain carbapenemases like KPC. According to CLSI breakpoints, susceptibility for most Enterobacteriaceae is defined at MIC ≤2 μg/mL, ≤8 μg/mL for P. aeruginosa, and ≤1 μg/mL for S. pneumoniae. However, cefepime shows poor activity against anaerobes, Enterococcus spp., methicillin-resistant S. aureus (MRSA), and has no efficacy against most fungi or viruses. Resistance patterns, often mediated by beta-lactamase production or efflux pumps, can elevate MICs beyond these thresholds in clinical isolates.

Pharmacology

Mechanism of action

Cefepime, a fourth-generation , exerts its bactericidal effects by binding to specific (PBPs) in susceptible bacteria, thereby inhibiting the final stages of synthesis in the . In , cefepime demonstrates high affinity for PBPs 1a, 1b, 2, and 3, while in , it binds effectively to PBPs 1a, 2, and 3. This binding covalently acylates the active sites of these transpeptidase enzymes, preventing the cross-linking of chains essential for integrity. The disruption of cross-linking leads to weakened cell walls, activating autolysins that cause further degradation and ultimately resulting in osmotic and bacterial death. This mechanism is time-dependent, with efficacy correlating to the duration of exposure above the . Cefepime's action is strictly bactericidal and does not interfere with bacterial protein synthesis or pathways, distinguishing it from other antibiotic classes like aminoglycosides or fluoroquinolones. A key feature enhancing cefepime's utility is its structural modification, including the aminothiazolyl imino group at the 7-position with an α-oxyimino substitution, which confers enhanced stability against hydrolysis by both chromosomal and plasmid-mediated β-lactamases, such as AmpC enzymes. This resistance allows cefepime to maintain activity against many β-lactamase-producing pathogens that would inactivate earlier-generation cephalosporins.

Pharmacokinetics

Cefepime is administered primarily via the route, which is preferred for its rapid onset and reliability in hospitalized patients, though injection is also an option for less severe cases. Following IM administration, cefepime exhibits complete with 100% , achieving concentrations comparable to IV dosing but with a slightly delayed time to maximum concentration. The drug distributes widely throughout the body, achieving therapeutic concentrations in various tissues such as the lungs, kidneys, , and soft tissues. Cefepime penetrates the (CSF), particularly in the presence of , with CSF-to-plasma ratios reaching up to 0.1 in cases, enabling its use in certain infections. Its steady-state volume of distribution is approximately 0.2 L/kg in healthy adults, reflecting good tissue penetration despite low of about 20%, which remains concentration-independent. Metabolism of cefepime is minimal, with approximately 15% undergoing hepatic to inactive metabolites such as N-methylpyrrolidine (NMP) and its N-oxide . The majority of the drug, over 85%, is excreted unchanged in the urine through a combination of glomerular filtration and tubular secretion, resulting in a total body clearance of about 120 mL/min in individuals with normal renal function. In adults with intact kidneys, the elimination is roughly 2 hours, but this extends significantly in special populations. Dosage adjustments are essential in renal impairment, where creatinine clearance (CrCl) below 60 mL/min necessitates reduced dosing frequency or amount to prevent accumulation; for CrCl 30-60 mL/min, dosing varies by indication—for example, 2 g every 12 hours for or intra-abdominal infections, but 1-2 g every 24 hours for urinary tract or skin infections. The is prolonged in elderly patients due to age-related declines in renal function and in critically ill individuals with augmented renal clearance or those on , often requiring to optimize efficacy and safety.

Adverse effects

Common adverse effects

Cefepime is generally well-tolerated, with common adverse effects being mild and self-limiting, primarily involving the , skin, injection site, and hematologic parameters. These effects occur in approximately 1-5% of patients in clinical trials, with and being the most frequent. Gastrointestinal disturbances are among the most common side effects, including (incidence of 2%), (1%), and (3%) in patients receiving multiple-dose regimens. These symptoms are typically mild and resolve upon discontinuation. difficile-associated is rare but can occur, necessitating prompt evaluation if persistent develops. Hypersensitivity reactions manifest as (4%), pruritus (1%), and urticaria (<1%), affecting 2-3% of patients overall. Anaphylaxis is uncommon, occurring in less than 1% of cases. Patients with a history of penicillin allergy face an estimated cross-reactivity risk of 1-10%, due to shared beta-lactam structures, though modern assessments suggest lower rates for fourth-generation cephalosporins like cefepime. Local reactions at the injection site, such as pain, inflammation, or , occur in 0.6-1.3% of intravenous administrations and are usually transient. Hematologic effects are generally mild and reversible, including transient and (up to 2% incidence). Positive direct without hemolysis has been observed in up to 16% of patients but rarely leads to clinical issues. Management of these common adverse effects involves supportive care, such as antiemetics for nausea or antihistamines for mild hypersensitivity; discontinuation of cefepime is recommended if reactions are severe or persistent. Regular monitoring of symptoms and laboratory parameters, especially in penicillin-allergic patients, helps mitigate risks.

Neurotoxicity

Cefepime, a fourth-generation cephalosporin, is associated with rare but serious neurotoxicity, primarily manifesting as central nervous system disturbances in patients with predisposing factors. This adverse effect is thought to arise from the drug's ability to cross the , particularly when plasma concentrations are elevated due to impaired clearance. The incidence of cefepime-induced neurotoxicity varies widely, estimated at approximately 6.2% in critically ill patients based on reviews of reported cases, with higher rates observed in intensive care unit (ICU) patients with renal impairment, reaching up to 15–24%. Common symptoms include myoclonus, seizures, encephalopathy, disorientation, altered mental status, and in severe cases, coma. The proposed mechanism involves competitive antagonism of in the central nervous system, leading to neuronal hyperexcitation and reduced inhibitory neurotransmission; cefepime may also decrease release or increase excitatory amino acids, exacerbating this effect after blood-brain barrier penetration. This toxicity is amplified by high plasma levels from accumulation in renal dysfunction or excessive dosing. Symptoms typically onset 2–6 days after initiating therapy, with a median of 3 days, and resolve within 1–3 days (up to 2–7 days) following discontinuation and dose adjustment, often accelerated by hemodialysis in severe cases. Key risk factors include renal dysfunction (creatinine clearance <30 mL/min, present in 80–87% of cases), elderly age (median 69 years), high-dose therapy (>6 g/day), preexisting injury, and elevated trough concentrations (>20 mg/L). A 2007 meta-analysis of 57 randomized trials suggested an increased all-cause mortality risk with cefepime compared to other beta-lactams (relative risk 1.26), prompting regulatory review; however, a subsequent 2009 FDA analysis and 2010 meta-analysis of over 17,000 patients found no significant mortality difference (6.21% vs. 6.00% for comparators).

Contraindications and precautions

Contraindications

Cefepime is contraindicated in patients with known immediate hypersensitivity reactions to cefepime or the cephalosporin class of antibacterial drugs, as well as in those with a history of anaphylaxis or other severe immediate hypersensitivity reactions to penicillins or other beta-lactam antibiotics. Cross-hypersensitivity between cephalosporins like cefepime and penicillins occurs in approximately 1% of patients with penicillin , though product labels conservatively estimate up to 10%; necessitating avoidance in those with severe penicillin . Although not absolute contraindications, cefepime should be used with caution in patients with a history of disorders, as it may increase the risk of , including , particularly when renal function is impaired and dosage adjustments are not made. In patients with renal impairment (creatinine clearance ≤60 mL/min), dose reduction is required to prevent accumulation and associated risks. There are no adequate and well-controlled studies of cefepime in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Cefepime was not teratogenic or embryocidal when administered during the period of organogenesis to rats at doses up to 40 times the recommended human dose. Cefepime is excreted in human breast milk at low concentrations (approximately 0.5 mcg/mL following a 1 g dose), and while the amount ingested by a nursing infant is minimal (about 0.5 mg/day assuming 1 L milk consumption), caution is advised due to potential gastrointestinal disturbances in the infant.

Drug interactions

Cefepime, primarily eliminated via renal tubular secretion and glomerular filtration, can interact with agents that affect renal function or excretion, potentially altering its pharmacokinetics and increasing toxicity risks. Concurrent administration of cefepime with nephrotoxic drugs such as aminoglycosides (e.g., gentamicin) or vancomycin heightens the risk of renal impairment, necessitating close monitoring of serum creatinine and renal function. This additive nephrotoxicity arises from shared renal stress, with studies showing lower acute kidney injury rates in septic patients receiving cefepime plus vancomycin compared to alternatives like piperacillin/tazobactam plus vancomycin. Probenecid inhibits the renal secretion of cefepime, thereby prolonging its and increasing its concentration, which may enhance but also the potential for adverse effects; dose adjustments are recommended in such combinations. Diuretics like can potentiate when used with cefepime, as observed with other cephalosporins, requiring vigilant renal monitoring during co-administration. Cefepime exhibits no significant interactions with enzymes, resulting in minimal effects on drugs metabolized by these pathways, including oral contraceptives and . In therapeutic combinations, cefepime demonstrates synergy with aminoglycosides against infections, improving bactericidal activity and eradication and clinically. It is also commonly paired with for coverage of anaerobic bacteria in complicated intra-abdominal infections, showing comparable efficacy and safety to monotherapy in randomized trials.

Chemistry

Chemical structure

Cefepime is a fourth-generation with the molecular formula C_{19}H_{24}N_6O_5S_2 and a molecular weight of 480.56 g/mol. Its IUPAC name is (6R,7R)-7-[[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(1-methylpyrrolidin-1-ium-1-yl)methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, reflecting its complex bicyclic framework. The core structure of cefepime consists of a β-lactam ring fused to a dihydrothiazine ring, forming the characteristic cephem nucleus of cephalosporins. At the C-7 position, it features a syn-methoximino aminothiazole , specifically the (2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-(methoxyimino), which contributes to its broad-spectrum activity. The C-3 position is substituted with an N-methylpyrrolidin-1-ium methyl group, introducing a positively charged quaternary ammonium moiety. This structural element distinguishes cefepime from third-generation cephalosporins, where a typically occupies the C-3 position; the quaternary ammonium group facilitates enhanced penetration through the outer membrane of and improves stability against certain β-lactamases. Cefepime exhibits specific critical to its pharmacological profile, including the (6R,7R) at the fused ring junctions of the cephem core. The moiety in the C-7 adopts the syn () geometry, which is known to optimize binding affinity to and overall antibacterial efficacy compared to the anti (E) .

Physical and chemical properties

Cefepime hydrochloride is a white to pale yellow crystalline powder. It is highly soluble in , with reported solubilities of up to 365 /mL at 23°C and 0.5, allowing for effective preparation of injectable solutions. The of a 1% typically ranges from 4.0 to 6.0, reflecting its zwitterionic character that influences in physiological conditions. The compound exhibits pKa values of approximately 2.82 for the strongest acidic group and 3.62 for the strongest basic group, which contribute to its across a range of environments. In dry form, cefepime remains stable under recommended storage conditions, but aqueous solutions are stable for up to 24 hours at controlled (20–25°C) or 7 days under refrigeration (2–8°C), provided compatibility with infusion fluids is maintained. Maximum occurs in the pH-independent region of 4 to 6, with degradation accelerating at alkaline or in the presence of certain metals like calcium or magnesium ions. Cefepime is formulated as the salt for parenteral , often combined with L-arginine (approximately 725 per gram of cefepime) to the solution between 4.0 and 6.0 and enhance compatibility. Degradation primarily involves of the ring.

History

Development and approval

Cefepime was developed by Bristol-Myers Squibb as a fourth-generation designed to address emerging resistance among , offering enhanced stability against beta-lactamases compared to earlier generations. The compound's synthesis and antibacterial properties were detailed in a key filed on March 31, 1982, under U.S. Patent No. 4,406,899, which described derivatives including cefepime for potent activity against both Gram-positive and Gram-negative pathogens. Pivotal clinical trials in the late and early demonstrated cefepime's efficacy and safety for treating serious infections, including nosocomial and complicated skin and skin structure infections, with success rates comparable to standard therapies like ceftazidime and imipenem-cilastatin in multicenter, randomized studies. These phase III trials, involving hundreds of patients, supported its approval for intravenous and intramuscular use, highlighting its broad-spectrum activity while maintaining a favorable pharmacokinetic profile with twice-daily dosing. Cefepime received initial regulatory approval in in 1993 and by the U.S. in 1996 under the brand name Maxipime, marking its entry into clinical practice for moderate-to-severe bacterial infections. It was launched in the United States in 1996, rapidly adopted for hospital use due to its versatility in empirical therapy. Cefepime was added to the World Health Organization's Model List of Essential Medicines in 2017 for specified bacterial diseases but removed in 2019 owing to the availability of more accessible alternatives.

Post-approval developments

Following the expiration of the Bristol-Myers Squibb patent in 2007, cefepime became available as a in the United States, enabling production and marketing by multiple manufacturers and increasing accessibility for treating bacterial infections. A 2007 and of 38 randomized controlled trials involving over 7,000 patients raised concerns about cefepime's safety, reporting higher all-cause mortality in cefepime-treated patients compared to those receiving other (risk ratio 1.26, 95% CI 1.08–1.49; approximately 15.6% vs. 10.9% in subgroup analyses). This prompted regulatory scrutiny, including a U.S. (FDA) review initiated in 2007 and culminating in a 2010 of 14 trials, which found no statistically significant increase in mortality associated with cefepime compared to other antibacterials ( 1.22, 95% CI 0.88–1.68). In response to rising antimicrobial resistance, particularly among metallo-beta-lactamase-producing Gram-negative bacteria, cefepime has been combined with novel beta-lactamase inhibitors in recent development programs. Cefepime-taniborbactam, designed to restore cefepime's activity against carbapenem-resistant pathogens, met its primary endpoint in the CERTAIN-1 Phase 3 trial for complicated urinary tract infections (topline results 2022; full publication 2024), demonstrating superiority to meropenem (composite success rate of 70.6% vs. 58.0%). The FDA accepted a resubmitted New Drug Application for cefepime-taniborbactam on November 8, 2025, following a complete response letter in 2024 that requested additional chemistry, manufacturing, and controls data but no new clinical trials. A Phase 3 trial (CERTAIN-2) for ventilated acute bacterial pneumonia and hospital-acquired bacterial pneumonia remains ongoing as of November 2025. Similarly, cefepime-zidebactam, targeting multidrug-resistant (MDR) Gram-negative infections including those caused by extensively drug-resistant Enterobacterales, met its primary endpoint in the ENHANCE-1 Phase 3 trial for complicated urinary tract infections (completed 2025), showing microbiological eradication rates comparable to meropenem in high-risk patients; Wockhardt submitted a New Drug Application to the FDA on October 1, 2025. Recent studies from 2024 and 2025 have highlighted emerging challenges with cefepime use in vulnerable populations. A 2025 of cancer patients found that cumulative cefepime exposure, particularly with prolonged courses exceeding 7 days, was associated with an increased hazard of developing ertapenem-non-susceptible, meropenem-susceptible bacteremia ( 1.15 per additional day, 95% 1.02–1.30), underscoring selective pressure for in neutropenic settings. Despite these risks, the global cefepime market is projected to grow at a (CAGR) of 5.2% from 2024 to 2033, reaching approximately USD 1.78 billion, driven by the escalating burden of MDR and demand for affordable fourth-generation cephalosporins in settings. Regulatory updates have also shaped cefepime's post-approval landscape. In 2019, the removed cefepime from its Model List of due to safety concerns in neutropenic patients and the availability of alternative beta-lactams with stronger evidence of efficacy. Concurrently, the FDA and Clinical and Laboratory Standards Institute (CLSI) have continued revising cefepime susceptibility breakpoints; for instance, CLSI's 2023 M100 edition updated interpretive criteria for based on pharmacokinetic/pharmacodynamic data and surveillance trends, with further refinements in the 2025 M100 edition (Ed35), including confirmatory testing guidance for cefepime MICs.

Society and culture

Brand names

Cefepime was originally marketed under the brand name Maxipime by Bristol-Myers Squibb in the United States, following its approval by the FDA in 1996. Internationally, cefepime is available under various proprietary names, including Axepim in and other countries, Cepimax in multiple regions, and Neopime in . In , it has also been distributed as Voco. Generic versions of cefepime became available in the United States after 2007, following the entry of the first formulations into the market. Generics appeared earlier in some international markets, such as and other developing regions, where they are marketed under names like Ceficad and Curepime. Globally, over 20 manufacturers produce cefepime formulations, including API suppliers like ACS Dobfar and Qilu Pharmaceutical, leading to more than 100 branded products worldwide. Investigational combinations involving cefepime, such as cefepime-taniborbactam, are under without established proprietary names for clinical use.

Availability

Cefepime is approved for medical use in numerous countries worldwide, including the where it received initial FDA approval in 1996 and became available as a in 2007 following expiration. In , it has been authorized since 1993. In , cefepime is classified under Schedule H1 of the Drugs and Cosmetics Rules, mandating prescription-only sales with mandatory record-keeping by pharmacies to curb antimicrobial misuse. Pricing for generic cefepime varies by region and formulation, with 1-gram vials typically costing $5–$15 USD for hospital procurement. Branded versions in developing markets often command higher prices, ranging from $20–$60 USD per gram, due to limited local manufacturing and import dependencies. Access to cefepime has faced challenges, including shortages in the attributed to manufacturing delays and quality issues at key production facilities, which disrupted supplies and prompted shifts to antibiotics. In 2019, the removed cefepime from its Model List of due to emerging resistance patterns and the availability of narrower-spectrum alternatives, though it continues to play a critical role in treating multidrug-resistant (MDR) Gram-negative infections where few options exist. As of 2025, global production of cefepime has ramped up to address rising in hospital settings, with market projections indicating sustained growth to meet demand for intravenous formulations. Investigational combinations, such as cefepime-taniborbactam ( rejected by FDA in 2024) and zidebactam-cefepime ( submitted to FDA in October 2025), remain in regulatory review and are not yet widely available for clinical use.