Pharma Co-pay Offset Programs
Pharma co-pay offset programs are manufacturer sponsored co-pay assistance programs directed at insured patients. Co-pay offset programs differ from patient assistance programs which focus on uninsured patients (or those denied coverage by their commercial plans) who meet financial eligibility criteria. 
How does it work?
a co-pay offset program as: “a manufacturer-sponsored co-pay program for branded pharmaceutical products directed at the commercially-insured population.” Co-pay offset programs differ from patient assistance programs (PAP), which focus on uninsured patients (or those denied coverage by their commercial plans) who meet financial eligibility criteria.
Despite controversy over co-pay programs, Zitter identified 561 co-pay offset programs in winter 2014, a 34% increase from the 419 programs in summer 2012. (See chart below.) The number of brands with co-pay offset programs grew even faster, from 440 brands in summer 2012 to 708 brands in winter 2014 (+61%). Note that a co-pay offset program can be applied to more than one brand, and vice versa.
Zitter also looked at how co-pay offset programs are used at specialty pharmacies. ZHI estimates that its sample accounts for about 25% of national specialty pharmacy claims.
The table below summarizes the results for the third quarter of 2013. On average, about 37% of specialty pharmacy prescriptions used a co-pay offset program, although usage varied dramatically among therapeutic class.