warnings and cautions
5 WARNINGS AND PRECAUTIONS Hypersensitivity Reactions: Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving therapy with beta-lactams. If an allergic reaction to PRIMAXIN occurs, discontinue the drug immediately ( 5.1 ). Seizure Potential: Seizures and other CNS adverse reactions, such as confusional states and myoclonic activity, have been reported during treatment with PRIMAXIN. If focal tremors, myoclonus, or seizures occur, patients should be evaluated neurologically, placed on anticonvulsant therapy if not already instituted, and the dosage of PRIMAXIN re-examined to determine whether it should be decreased, or the antibacterial drug discontinued ( 5.2 ). Increased Seizure Potential Due to Interaction with Valproic Acid: Co-administration of PRIMAXIN, to patients receiving valproic acid or divalproex sodium results in a reduction in valproic acid concentrations. The valproic acid concentrations may drop below the therapeutic range as a result of this interaction, therefore increasing the risk of breakthrough seizures. The concomitant use of PRIMAXIN and valproic acid/divalproex sodium is generally not recommended ( 5.3 , 7.3 ). Clostridioides difficile-Associated Diarrhea (CDAD): has been reported with use of PRIMAXIN and may range in severity from mild diarrhea to fatal colitis. Evaluate if diarrhea occurs ( 5.4 ). 5.1 Hypersensitivity Reactions Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving therapy with beta-lactams. These reactions are more likely to occur in individuals with a history of sensitivity to multiple allergens. There have been reports of individuals with a history of penicillin hypersensitivity who have experienced severe hypersensitivity reactions when treated with another beta-lactam. Before initiating therapy with PRIMAXIN, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins, other beta-lactams and other allergens. If an allergic reaction to PRIMAXIN occurs, discontinue the drug immediately. Serious anaphylactic reactions require immediate emergency treatment as clinically indicated. 5.2 Seizure Potential Seizures and other CNS adverse experiences, such as confusional states and myoclonic activity, have been reported during treatment with PRIMAXIN, especially when recommended dosages were exceeded [see Adverse Reactions (6.1 , 6.2 )]. These experiences have occurred most commonly in patients with CNS disorders (e.g., brain lesions or history of seizures) and/or compromised renal function [see Use in Specific Populations (8.6) ] . However, there have been reports of CNS adverse experiences in patients who had no recognized or documented underlying CNS disorder or compromised renal function. Anticonvulsant therapy should be continued in patients with known seizure disorders. If focal tremors, myoclonus, or seizures occur, patients should be evaluated neurologically, placed on anticonvulsant therapy if not already instituted, and the dosage of PRIMAXIN re-examined to determine whether it should be decreased, or the antibacterial drug discontinued. 5.3 Increased Seizure Potential Due to Interaction with Valproic Acid Case reports in the literature have shown that co-administration of carbapenems, including PRIMAXIN, to patients receiving valproic acid or divalproex sodium results in a reduction in valproic acid concentrations. The valproic acid concentrations may drop below the therapeutic range as a result of this interaction, therefore increasing the risk of breakthrough seizures. Increasing the dose of valproic acid or divalproex sodium may not be sufficient to overcome this interaction. The concomitant use of PRIMAXIN and valproic acid/divalproex sodium is generally not recommended. Antibacterials other than carbapenems should be considered to treat infections in patients whose seizures are well controlled on valproic acid or divalproex sodium. If administration of PRIMAXIN is necessary, supplemental anti-convulsant therapy should be considered [see Drug Interactions (7.3) ]. Close adherence to the recommended dosage and dosage schedules is urged, especially in patients with known factors that predispose to convulsive activity. 5.4 Clostridioides difficile -Associated Diarrhea (CDAD) Clostridioides difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including PRIMAXIN, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial drug use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibacterial drug use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial drug treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated. 5.5 Development of Drug-Resistant Bacteria As with other antibacterial drugs, prolonged use of PRIMAXIN may result in overgrowth of nonsusceptible organisms. Repeated evaluation of the patient's condition is essential. If superinfection occurs during therapy, appropriate measures should be taken. Prescribing PRIMAXIN in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.