Factors Associated With Generic Drug Uptake in the United States, 2012 to 2017

Does the first generic exclusivity system provide an economic incentive for early generic entrance under the patent linkage system?

Introduction

A period of exclusivity for the first generics, as part of the patent linkage system, was established in South Korea to provide an economic incentive for early generic entry. This study describes the dynamics of generic penetration and assesses the first mover market share advantages under the patent linkage system.

Methods

Pairs of originators and their corresponding generics granted the first generic exclusivity from 2015 to 2020 were identified. We categorized generics into first movers and latecomers, described the penetration curves of generics, and estimated the saturated market share of generics, first movers, and latecomers. Volume-based monthly prescriptions were used to describe the generics' penetration curves. A logistic growth model was adopted to estimate the saturated market shares of generics.

Results

We identified 28 pairs of originators and generics, presented penetration curves, and estimated generics market shares. The saturated market share of generics was 30%, and the time to saturation was approximately 33 months. The shapes of penetration varied by nationality, route, and number of generics. The existence of latecomers was associated with the decreased penetration speed over time and decreased market share of generics. However, the first mover market share advantages or latecomers' disadvantages were consistently observed.

Conclusion

The generic uptake in South Korea is delayed, limited, and context-dependent. However, first generics' market share advantage suggests that a period of exclusivity, as part of the patent linkage system, could provide an economic incentive for early generic entrance.

Using Multiple Authorized Generics to Maintain High Prices: The Example of Entacapone

OBJECTIVES

Brand-name drug manufacturers can market or license authorized generics (AGs), which are the same product sold under a generic name. By contrast, independent generics (IGs) are made by other manufacturers. The brand-name manufacturer of entacapone, a treatment for Parkinson's disease, established 4 AGs before IGs emerged. We used this case study to understand how AGs can affect the length of brand-name exclusivity and robustness of generic competition.

METHODS

Using public Food and Drug Administration and court records, we identified the regulatory and legal history for generic entacapone products marketed through 2021. We used Medicare Part D data to estimate trends in use, prices, and spending on entacapone products from 2011 to 2020, comparing actual spending with projected spending if IG competition had begun after expiration of the key patent protecting entacapone (October 2013) and prices had fallen consistent with levels observed for other generic drugs.

RESULTS

From 2012 to 2014, 3 potential entacapone IG manufacturers instead launched AG versions after settlement agreements with the brand-name manufacturer; the brand-name manufacturer additionally introduced its own AG. Four different IG versions were marketed beginning in 2015. From 2011 to 2020, average Medicare prices declined by 62%, less than the projected 74% to 92% price decline expected for a drug with 8 generics. Over this period, Medicare spent $1.1 billion on entacapone products, which could have been reduced by an estimated $137 to $449 million through typical IG competition.

CONCLUSIONS

The case of entacapone demonstrates how licensing multiple AGs in place of IG competition can increase spending. Government regulators should more rigorously monitor AGs to prevent such strategies.

Patient Out-of-Pocket Costs Following the Availability of Biosimilar Versions of Infliximab

After market exclusivity ends for biologic drugs, biosimilars-follow-on versions made by other manufacturers-can compete with lower prices. Biosimilars have modestly reduced prescription drug spending for US payers, but it is unclear whether patients have directly experienced any savings. In this study we assessed whether availability of biosimilar infliximab was associated with lower out-of-pocket (OOP) costs, using claims from a national data set of commercially insured patients from 2014 to 2018. We used two-part models, adjusting for patient demographics, clinical characteristics, insurance plan type, and calendar month. Compared with the reference biologic, there was no difference in the percentage of biosimilar claims with OOP costs (30.1% vs. 30.8%; adjusted odds ratio (aOR) 0.98, 95% confidence interval (CI), 0.84-1.15, P = 0.84) or the average nonzero OOP cost (median $378 vs. $538, adjusted mean ratio (aMR) 0.97, 95% CI, 0.80-1.18, P = 0.77). The percentage of claims with OOP costs was lower after biosimilar competition (30.7% vs. 35.0%, aOR 0.96, 95% CI, 0.94-0.99, P = 0.003), but average nonzero costs increased (median $534 vs. $520, aMR 1.04, 95% CI, 1.01-1.07, P = 0.004). Thus, early biosimilar infliximab competition did not improve affordability for patients. Policymakers need to better assure that competition in the biosimilar market translates to lower costs for patients using these medications.

State Laws and Generic Substitution in the Year After New Generic Competition

OBJECTIVES

Substitution of brand-name drugs with less expensive, equally effective interchangeable generics is an important strategy for promoting adherence and controlling prescription drug spending. US state laws govern generic substitution, but there is variability among states in how these laws are designed. We aimed to determine how different features of state laws regulating generic substitution are associated with use of generic drugs.

METHODS

Using national claims databases, we studied individuals with commercial insurance or Medicare Advantage plans who newly initiated one of 34 prescription drugs during the year after new generic competition (2017-2018) to determine any association between generic use and 3 different features of state laws. We used multivariable logistic regression to adjust for demographic and clinical characteristics.

RESULTS

Of 502 763 individuals who initiated one of the drugs, 409 856 (81.6%) received a generic version. Those in states requiring patient consent or notification had lower use of generics (81.1% vs 82.9%; adjusted odds ratio 0.89; 95% confidence interval 0.87-0.91; P < .001). By contrast, mandating versus permitting generic substitution and protecting pharmacists from liability did not appear to have significant effects.

CONCLUSIONS

In this study of commercially insured and Medicare Advantage patients, patients in states requiring consent or notification for pharmacists to substitute Food and Drug Administration-certified interchangeable generics had lower use of generics. Laws in 39 states plus the District of Columbia could be amended to improve use of inexpensive and equally effective generic drugs.

Indication-Specific Generic Uptake of Imatinib Demonstrates the Impact of Skinny Labeling

PURPOSE

Generic competition can be delayed if brand-name manufacturers obtain additional patents on supplemental uses. The US Food and Drug Administration allows generic drug manufacturers to market versions with skinny labels that exclude patent-protected indications. This study assessed whether use of generic versions of imatinib varied between indications included and excluded from the skinny labels.

METHODS

In this cross-sectional study, we identified adult patients covered by commercial insurance or Medicare Advantage plans who initiated imatinib from February 2016 (first generic availability) to September 2020. Generic versions were introduced with skinny labels that included indications covering treatment of chronic myelogenous leukemia (CML) but excluded treatment of gastrointestinal stromal tumors (GISTs) because of remaining patent protections. Logistic regression was used to determine whether use of generic versus brand-name imatinib differed between patients with a diagnosis of CML or GIST, adjusting for demographics, insurance type, prior use of brand-name drugs, and calendar month.

RESULTS

Among 2,000 initiators, 934 (47%) had CML and 686 (34%) had GIST. Within 3 years after generics entered the market, more than 90% of initiators in both groups used generic imatinib. Initiation of generic imatinib was slightly lower among patients with GIST than among patients with CML (85% v 88%; adjusted odds ratio 0.56; 95% CI, 0.39 to 0.80; P ≤ .001).

CONCLUSION

Generic versions of imatinib were dispensed frequently for indications both included (CML) and excluded (GIST) from the skinny labeling, although patients with GIST were slightly less likely to receive a generic version. The skinny labeling pathway allowed generics to enter the market before patent protection for treating patients with GIST expired, facilitating lower drug prices.

Trends in Use and Expenditures for Brand-name Statins After Introduction of Generic Statins in the US, 2002-2018

IMPORTANCE

The high and increasing expenditures for prescription medications in the US is a national problem.

OBJECTIVE

To explore the association of generic statin competition on relevant use and cost savings and to provide use and expenditure trends for all available statins for private and public payers and for out-of-pocket spending.

DESIGN, SETTING, AND PARTICIPANTS

This survey study evaluated data from the January 1, 2002, to December 31, 2018, Medical Expenditure Panel Survey by using a difference-in-differences analysis. Participants included noninstitutionalized individual statin users. Data were analyzed from November 1, 2020, to March 30, 2021.

EXPOSURES

The market entry of 5 generic statin medications (atorvastatin, rosuvastatin, simvastatin, lovastatin, and pravastatin).

MAIN OUTCOMES AND MEASURES

National- and individual-level reductions in the annual number of statin purchases and total expenditures across private insurance, public insurance (Medicaid and Medicare), and out-of-pocket spending (presented in 2018 US dollars).

RESULTS

Between January 1, 2002, and December 31, 2018, an average of 21.35 million statins (95% CI, 16.7-25.5 million) were purchased annually, with an average total annual cost of $24.5 billion (95% CI, $18.2-$28.8 billion). The number of brand-name statin purchases decreased by 90.9% (95% CI, 56%-98%) nationally and 27.4% (95% CI, 13%-40%) individually after the end of market exclusivity. Among major payers, the end of market exclusivity was associated with individual cost savings of $370.00 (95% CI, $430.70-$309.20) for private insurers, $281.00 (95% CI, $346.80-$215.30) for Medicare, $72.34 (95% CI, $95.22-$49.46) for Medicaid, and $211.90 (95% CI, $231.20-$192.50) for out-of-pocket spending. Combining all payers, the decrease translates to $925.60 (95% CI, $1005.00-$846.40) of annual savings per individual and $11.9 billion (95% CI, $10.9-$13.0 billion) for the US.

CONCLUSIONS AND RELEVANCE

Results of this survey study suggest that full generic competition of statins was associated with significant cost savings across all major payers within the US health care system.