A number of medicinal products influence glucose metabolism and possible interactions should therefore be taken into account by the physician.
Combination with ACE-inhibitors, NSAIDs, salicylates, monoamine oxidase inhibitors, non-selective beta-adrenergic-blocking agents and anabolic hormones
The following agents may enhance the hypoglycaemic effect of nateglinide: angiotensin-converting enzyme inhibitors (ACEI), non-steroidal anti-inflammatory agents, salicylates, monoamine oxidase inhibitors, non-selective beta-adrenergic-blocking agents and anabolic hormones (e.g. methandrostenolone).
Diuretics, corticosteroids, beta2 agonists, somatropin, somatostatin analogues, rifampin, phenytoin and St. John's Wort (Hypericum perforatum)
The following agents may reduce the hypoglycaemic effect of nateglinide: diuretics, corticosteroids, beta2 agonists, somatropin, somatostatin analogues (e.g. lanreotide, octreotide), rifampin, phenytoin and St. John's Wort (Hypericum perforatum).
When these medicinal products - that enhance or reduce the hypoglycaemic effect of nateglinide - are administered to or withdrawn from patients receiving nateglinide, the patient should be observed closely for changes in glycaemic control.
CYP2C9 and CYP3A4 substrates
Data available from both in vitro and in vivo experiments indicate that nateglinide is predominantly metabolised by CYP2C9 with involvement of CYP3A4 to a smaller extent.
In an interaction trial with sulfinpyrazone, a CYP2C9 inhibitor, a modest increase in nateglinide AUC (~28%) was observed in healthy volunteers, with no changes in the mean Cmax and elimination half-life. A more prolonged effect and possibly a risk of hypoglycaemia cannot be excluded in patients when nateglinide is co-administered with CYP2C9 inhibitors.
Particular caution is recommended when nateglinide is co-administered with other more potent inhibitors of CYP2C9 (e.g. fluconazole, gemfibrozil or sulfinpyrazone), or in patients known to be poor metabolisers for CYP2C9 substrates.
Interaction studies with a CYP3A4 inhibitor have not been carried out in vivo.
In vivo, nateglinide has no clinically relevant effect on the pharmacokinetics of medicinal products metabolised by CYP2C9 and CYP3A4. The pharmacokinetics of warfarin (a substrate for CYP3A4 and CYP2C9), diclofenac (a substrate for CYP2C9), and digoxin were unaffected by coadministration with nateglinide. Conversely, these medicinal products had no effect on the pharmacokinetics of nateglinide. Thus, no dosage adjustment is required for digoxin, warfarin or other drugs that are CYP2C9 or CYP3A4 substrates upon coadministration with Starlix. Similarly, there was no clinically significant pharmacokinetic interaction of Starlix with other oral antidiabetic agents such as metformin or glibenclamide.
Nateglinide has shown a low potential for protein displacement in in vitro studies.