Voltaren/Voltaren SR Drug Interactions

The following interactions were observed with Voltaren and/or other pharmaceutical forms of diclofenac.
Lithium: Diclofenac may increase plasma concentrations of co-administered lithium. Monitoring of serum lithium levels is recommended.
Digoxin: Diclofenac may increase plasma concentrations of co-administered digoxin. Monitoring of serum digoxin levels is recommended.
Diuretics and antihypertensive agents: As with other NSAIDs, co-administration of diclofenac may reduce the antihypertensive effects of diuretics or antihypertensive agents (e.g. beta-blockers, angiotensin-converting-enzyme [ACE] inhibitors). Therefore, the combination should be administered with caution, and patients, especially the elderly, should have their blood pressure monitored regularly. Patients should be adequately hydrated, and consideration should be given to monitoring of renal function after initiation of concomitant therapy and periodically thereafter, particularly with diuretics and ACE inhibitors due to the increased risk of nephrotoxicity (see Warnings and Precautions).
Other NSAIDs and corticosteroids: Concomitant administration of diclofenac and other systemic NSAIDs or corticosteroids may increase the frequency of gastrointestinal adverse effects (see Precautions).
Anticoagulants and antiplatelet agents: Caution is required since co-administration could increase the risk of bleeding (see Precautions). Although clinical investigations do not appear to indicate that diclofenac affects the action of anticoagulants, there have been reports of an increased risk of bleeding in patients receiving diclofenac and anticoagulants concomitantly. Close monitoring of such patients is therefore recommended.
Selective serotonin reuptake inhibitors (SSRIs): Co-administration of systemic NSAIDs, including diclofenac, and SSRIs may increase the risk of gastrointestinal bleeding (see Precautions).
Antidiabetic agents: Clinical studies have shown that diclofenac can be given together with oral antidiabetic agents without influencing their clinical effect. However, there have been isolated reports of both hypoglycaemic and hyperglycaemic reactions following administration of diclofenac, requiring adjustment of the dosage of the antidiabetic agent. For this reason, monitoring of blood glucose levels is recommended as a precautionary measure during combination therapy.
Methotrexate: Caution is required when NSAIDs, including diclofenac, are administered less than 24 hours before or after treatment with methotrexate because blood levels of methotrexate may rise, and methotrexate toxicity may increase.
Ciclosporin: Diclofenac, like other NSAIDs, may increase the nephrotoxicity of ciclosporin due to the effect on renal prostaglandins. Therefore, it should be given at doses lower than those that would be used in patients not receiving ciclosporin.
Quinolone antibiotics: There have been isolated reports of convulsions that may have been due to concomitant use of quinolones and NSAIDs.
Phenytoin: If phenytoin is used concomitantly with diclofenac, monitoring of phenytoin plasma concentrations is recommended due to an expected increase in exposure to phenytoin.
Voltaren EC tablet/suppository: Drugs known to cause hyperkalaemia: Concomitant treatment with potassium-sparing drugs may be associated with increased serum potassium levels, which should therefore be monitored frequently.
Potent CYP2C9 inhibitors: Caution is recommended when co-prescribing diclofenac with potent CYP2C9 inhibitors (such as sulfinpyrazone and voriconazole), which could result in a significant increase in peak plasma concentrations and exposure to diclofenac due to inhibition of diclofenac metabolism.
Voltaren SR-FC tablet: CYP2C9 inducers: Caution is required when co-administering diclofenac with CYP2C9 inducers (such as rifampicin). This could result in a significant decrease in plasma concentration and exposure to diclofenac.
CYP2C9 inhibitors: Caution is required when co-administering diclofenac with CYP2C9 inhibitors (such as voriconazole). This could result in a significant increase in peak plasma concentrations and exposure to diclofenac.
Tacrolimus: Diclofenac, like other NSAIDs, may increase the nephrotoxicity of tacrolimus due to the effect on renal prostaglandins. Therefore, it should be given at doses lower than those that would be used in patients not receiving tacrolimus.
Drugs known to cause hyperkalaemia: Concomitant treatment with potassium-sparing diuretics, ciclosporin, tacrolimus or trimethoprim may be associated with increased plasma potassium levels, which should therefore be monitored frequently.
Antidiabetic agents: There have also been isolated reports of metabolic acidosis when diclofenac was co-administered with metformin, especially in patients with pre-existing renal impairment.