Co-possession of phosphodiesterase type-5 inhibitors (PDE5-I) with nitrates

Abstract

Objective:

Estimate the proportion of phosphodiesterase type-5 inhibitor (PDE5-I) patients who co-possess nitrates and compare the proportion of tadalafil patients dispensed nitrates to a matched control group. Secondarily, examine the percentage of co-possession of PDE5-Is and nitrates where the products were dispensed on the same day or written by the same prescriber.

Methods:

Male patients aged 18+ years filling PDE5-I prescriptions between December 2003 and March 2006 were identified using a U.S. longitudinal prescription database (IMS Health LRx™). Similar patients not dispensed a PDE5-I during this period were matched to the tadalafil-dispensed cohort using a propensity score approach. Co-possession, as a proxy for concurrent use, was defined as an overlap in time on therapy for a PDE5-I and nitrate and was compared for the three PDE5-Is and for tadalafil to the matched control group.

Results:

Among 601,063 tadalafil patients, 3.31% were dispensed a nitrate during the study period, compared to 6.18% in control patients (n = 601,063). When co-possessed prescriptions were defined by overlapping exposure periods, the proportion of PDE5-I patients with co-possessed nitrates ranged from 1.44% (tadalafil) to 1.72% (vardenafil) and 2.13% (sildenafil). Co-possession percentages of PDE5-I prescriptions were 0.83% for tadalafil and 1.07% for sildenafil and vardenafil. The majority (54.29%) of co-possessed PDE5-I and nitrate prescriptions had the nitrate dispensed prior to the PDE5-I prescription identified in the study cohort.

Conclusions:

Keeping in mind the limitations of observational studies, these results suggest that co-dispensing of nitrates and PDE5-Is is low. Compared to control patients, the proportion of nitrate co-possession was lowest for patients filling tadalafil. Tadalafil patients also had the lowest co-possessed proportion among the three PDE5-I cohorts. While the majority of co-possessed drug pairs were prescribed by different providers, the highest percentage of co-prescribing from the same physician was among cardiologists. These results suggest that physicians adhere to contraindications and are careful about co-prescribing of nitrates with PDE-5Is.

Key words::

• Co-possession
• Erectile dysfunction
• Nitrates
• Phosphodiesterase type-5 inhibitors
• Tadalafil

Transparency

Declaration of funding

Funding for this study was provided by Eli Lilly, Inc.; however, publication of study results was not contingent on the sponsor’s approval.

Declaration of financial/other relationships

Authors L.-L.C., H.v.A., and S.C.H. have declared that they are employees of IMS Health, Inc., a provider of market intelligence to the pharmaceutical and healthcare industries. L.M., K. Harper, and K. Hornbuckle are employees and stockholders of Eli Lilly. Peer reviewers may receive honoraria from CMRO for their review work. The peer reviewers of this paper have disclosed that they have no relevant financial relationships.

Acknowledgments

The authors wish to thank the following for their assistance and helpful comments in reviewing the study results and manuscript. From Eli Lilly, Inc.: David Riggs, MD; Timothy Costigan, PhD; Kenneth Conrad, MS; David P Sundin, PhD. From IMS Health, Inc: Boyung Pahls, MPH; Nick DeFabis; Elise Pelletier, MS; and Lisa Morris, RPh.