Ceftazidime/Avibactam Pfizer In vitro drug combination studies with Ceftazidime/Avibactam Pfizer have demonstrated neither synergy nor antagonism with the following drugs: metronidazole, tobramycin, levofloxacin, vancomycin, linezolid, colistin and tigecycline.

Interaction with other antimicrobial agents: Chloramphenicol is antagonistic in vitro with ceftazidime and other cephalosporins. The clinical relevance of this finding is unknown, but due to the possibility of antagonism in vivo, this drug combination should be avoided.

Interaction with other medicinal products and other forms of interaction: In vitro, probenecid, a potent OAT inhibitor, inhibits avibactam uptake by 56–70%, potentially altering the elimination of avibactam. Since a clinical interaction trial of avibactam and probenecid has not been conducted, co-administration is not recommended. Avibactam showed no significant inhibition of cytochrome P450 enzymes in vitro. Avibactam and ceftazidime showed no in vitro cytochrome P450 induction at clinically relevant concentrations. Avibactam and ceftazidime do not inhibit the major renal or hepatic transporters in the clinically relevant exposure range, therefore the interaction potential via these mechanisms is considered low.
Clinical data have demonstrated that there is no interaction between ceftazidime and avibactam, and between Ceftazidime/Avibactam Pfizer and metronidazole.
Concurrent treatment with high doses of cephalosporins and nephrotoxic medicinal products, such as aminoglycosides or potent diuretics (e.g. furosemide), may adversely affect renal function.

• Hypersensitivity to the active substances or to any of the excipients
• Hypersensitivity to any cephalosporin antibacterial agent
• Severe hypersensitivity (e.g., anaphylactic reaction, severe skin reaction) to any other type of β-lactam antibacterial agent (e.g., penicillins, monobactams or carbapenems)

Hypersensitivity reactions
Serious and occasionally fatal hypersensitivity reactions are possible. In case of hypersensitivity reactions, treatment with Ceftazidime/Avibactam Pfizer must be discontinued immediately and adequate emergency measures must be initiated.
Before beginning treatment, it should be established whether the patient has a history of hypersensitivity reactions to ceftazidime, to other cephalosporins or to any other type of β-lactam antibacterial agent. Caution should be used if ceftazidime and avibactam is given to patients with a history of non-severe hypersensitivity to penicillins, monobactams or carbapenems.

Clostridium difficile-associated diarrhoea
Clostridium difficile-associated diarrhoea has been reported with ceftazidime and avibactam, and can range in severity from mild to life-threatening. This diagnosis should be considered in patients who present with diarrhoea during or subsequent to the administration of Ceftazidime/Avibactam Pfizer. Discontinuation of therapy with Ceftazidime/Avibactam Pfizer and the administration of specific treatment for Clostridium difficile should be considered. Medicinal products that inhibit peristalsis should not be given.