Table 2.

Empirical studies of the implications of patenting on price

Authors/ Ref. no.	Period	Setting (Country/medicines)	Objectives	Model	Method
Watal (2000)/[17]	1985-1992	India, 22 patentable medicines in mailbox (varied in wide therapeutic areas)	The effect of product patents, price control and compulsory licensing on medicine prices and welfare.	Demand function estimation	Comparing effects from different demand functions—the constant elasticity demand and the linear demand function—and estimating price as a composite of the demand function.
Fink (2000)/[18]	1992	India, two therapeutic groups: quinolones and synthetic hypotensives	The impact of product patents on medicine price and pharmaceutical company’s profit	Demand function estimation	Modeling a demand function as a two-stage decision-making process (chemical entity and brands under that chemical entity). Then estimating price and profit under each substitution elasticity among chemical entities and among brands.
Boersma et.al. (2005)/[19]	1996 to 2001	The Netherlands, three medicines whose patents expired between 1996 and 2001	To observe price and share prior to and after patent expiration	Observational study	Trend analysis of volumes and price (measured as defined daily doses (DDD) prior to and after patent expiries were calculated
Suh et al. (2000)/[20]	1984-1987	USA, 35 chemical entities whose patents expired between 1984 and 1987	The effect of generic medicine entry on price after patent expiration	Regression analysis	Collecting descriptive statistics of price after patent expiration and analysing the influential factors affecting price, which are number of multiple-source medicines, market growth, market size, profitability, severity of illness, duration of treatment, and number of years after patent expiration.
Magazzini et al. (2004)/[21]	July 1987-December 1998 (Quarterly data)	USA, UK, Germany, and France, all medicines whose patents expired within the study period	Price and determinant of price after patent expiry	Regression analysis	Collecting descriptive statistics of prices before and after patent expiration. Using regression of the price with control of market share of the patented products, market size, % of sales to the hospital segment, the average market growth, the number of brand names, ratio of the average price of original products, etc.
Grabowski and Vernon (1992)/[22]	1983-1986	USA, 18 expired patent medicines	The pricing and competitive behaviour after patent expiration	Regression analysis	Using descriptive statistics of price index of the overall market, original medicine, and generic medicine. Using regression of the determinant of generic entry.
Griliches and Cockburn (1994)/[23]	1987-1990	USA, two anti-infective drugs: cephalexin and cephradine	The pricing and competitive behaviour after patent expiration	Observational study	Calculating the aggregate price indexes for a simple two-goods world where consumers buy either the brand or the generic version of a drug.
Borrell (2007)/[26]	1995-2000	14 antiretroviral therapy medicines in 34 low and middle income countries.	The impact of patents on medicine prices across developing countries	Regression analysis	Developing a price function as a composite function of the number of medicines in patent and non-patent regimes, number of generics after patent expiration, number of doses per day, efficacy, adverse reactions, and number of years in the US market.
Supakankunti et. al. (1999)/[27]	1987-1998	Thailand, six therapeutic categories were chosen to represent the patented market	The effect of new patent law on price	Observational study	There were no patented medicines so these medicines were selected by other criteria. Descriptive statistics were used to report the price movement or trend of the real price and nominal price of branded and generic medicines.
Limpananont et. al. (2004)/[28]	2001-2004	Thailand, antiretroviral therapy medicines	Price differences of patented and generic medicines	Observational study	Comparing and calculating the price ratio of patented and generic DDD prices
Jones et al. (2001)/[29]	1981-1994	Canada, 82 medicines from the British Columbia Pharmacare Programme.	The impact of the Canadian Patent Act in 1987	Regression analysis	Using descriptive statistics of prices before and after 1987 and log regression of generic market share, one factor, to predict market price.
Challu (1995)/’ [30]	1987-	Italy, 38 medicines	The impact of the 1978 patent law change	Observational study	Comparing new drug prices in Italy before and after the 1978 patent law. Using US prices as a reference.