Saxagliptin plus metformin combination therapy

A retrospective study of persistence, adherence, and health economic outcomes of fixed-dose combination vs. loose-dose combination of oral anti-diabetes drugs

OBJECTIVE

To compare outcomes between patients with type 2 diabetes mellitus (T2DM) using fixed-dose combination (FDC) and loose-dose combination (LDC) products.

METHODS

This retrospective cohort study used MarketScan Commercial and Medicare Supplemental data from January 1, 2009-December 31, 2013. The identified population included patients with T2DM and ≥1 additional oral anti-diabetic prescription (of the same regimen [FDC/LDC] as the index prescription) within 12 months following the fill date. Persistence (no ≥30-day gap) and adherence (medication possession ratio [MPR] ≥0.8) were assessed as primary end-points; secondary end-points included hypoglycemia, healthcare resource utilization, and costs.

RESULTS

Of 23,361 patients identified, 12,590 (53.9%) were on FDC therapy and 10,771 (46.1%) were on LDC therapy. FDC patients had a significantly lower rate of non-persistence (67.9% vs. 73.4%, p < 0.0001) and a significantly higher rate of adherence to therapy (57.0% vs. 50.7%, p < 0.0001) when compared to LDC patients. Average time to non-persistence was significantly longer among FDC vs. LDC patients (207.1 vs. 186.3 days, p < 0.0001). After adjusting for baseline characteristics, the odds of non-persistence were 21% lower with FDC vs. LDC therapy (OR = 0.79, 95% CI = 0.74-0.85, p < 0.0001), with a 28% higher odds of adherence (OR = 1.28, 95% CI = 1.20-1.36, p < 0.0001). Differences in most secondary outcomes significantly favored FDC therapy, including total predicted monthly all-cause costs ($1008 vs. $1053; p = 0.006) and T2DM-related costs ($142 vs. $155; p < 0.001).

LIMITATIONS

Cohort classification was based on prescription claims data. The lack of clinical data limits assessment of potential influencers of FDC vs. LDC decisions, residual confounding was possible, and diabetes-related medical costs only captured claims with a primary diagnosis for diabetes. The results may not be generalizable to populations such as Medicaid.

CONCLUSION

Management of T2DM using FDC therapies provides a compliance benefit relative to LDC therapies that may translate to reductions in healthcare utilization and costs.

Saxagliptin overview: special focus on safety and adverse effects

INTRODUCTION

Saxagliptin (see drug summary box) is a glucose-lowering agent that belongs to the class of Dipeptidylpeptidase-4 (DDP-4) inhibitors used in the treatment of T2DM. Clinical efficacy of saxagliptin as single agent as well as in combination with other medications used for the treatment of T2DM has been well established in several randomized trials. Treatment with saxagliptin is effective, generally safe and well tolerated, apart from a small increase in the incidence of infections such as nasopharyngitis. Its use is not associated with increase risk of hypoglycemia and it is weight neutral. Saxagliptin can be used safely in renal failure (with dose adjustment) and in hepatic impairment. When saxagliptin is used in combination with a strong inhibitor of CYP3A4/A5, reduction in the daily dosage is recommended.

AREAS COVERED

This paper briefly discusses efficacy and pharmacokinetics of saxagliptin. The paper highlights in detail saxagliptin-associated adverse effects, drug interactions, its use in patients with renal and hepatic disease and long-term safety concerns.

EXPERT OPINION

Saxagliptin has comparable efficacy with other DPP-4 inhibitors. It is generally safe and well tolerated; however, it requires dose adjustment in renal disease as well as when used with drugs that are strong inhibitor or inducer of CYP3A4/A5 isoforms. Future safety questions regarding immune system and development of cancer still remain to be completely answered.