International Strategies for Tropical Disease Treatments - Experiences with Praziquantel - EDM Research Series No. 026
(1998; 113 pages) View the PDF document
Table of Contents
View the documentAbstract
View the documentAcknowledgments
View the documentInformation on authors
View the documentExchange rates used in the report
Open this folder and view contentsChapter 1: Policies for praziquantel*
Close this folderChapter 2: Bayer & E. Merck: Discovery and development of praziquantel*
View the documentPrecursors of praziquantel at Bayer and E. Merck
View the documentDiscovery process and initial testing of praziquantel
View the documentWHO and Bayer cooperation
View the documentCompeting drugs for schistosomiasis treatment
View the documentVeterinary uses of praziquantel
View the documentReferences
Open this folder and view contentsChapter 3: Shin Poong Pharmaceutical Co.: Process development in the Republic of Korea*
Open this folder and view contentsChapter 4: The Egyptian International Pharmaceutical Industries Co.: Praziquantel formulation*
Open this folder and view contentsChapter 5: The international supply of praziquantel*
Open this folder and view contentsChapter 6: Demand for praziquantel and national distribution*
Open this folder and view contentsChapter 7: Prices and production costs of praziquantel*
View the documentOther documents in the DAP Research Series
View the documentDAP Research Series No. 26
 

Chapter 2: Bayer & E. Merck: Discovery and development of praziquantel*

* By Michael R. Reich, Agnes Brinkmann, and Ramesh Govindaraj.

The most important development in recent decades in the treatment of schistosomiasis is the discovery of praziquantel. This pharmaceutical product is the first anthelminthic drug to fulfill the World Health Organization’s requirements for population-based chemotherapy of a broad range of parasitic infections (Wegner, 1981). This chapter presents some of the therapeutic precursors of praziquantel, and then describes the discovery and initial testing of praziquantel, with particular attention to the role of WHO. Competing drugs for schistosomiasis treatment and the veterinary uses of praziquantel are briefly discussed.

This report does not provide a review of the biology and epidemiology of schistosomiasis, or of the clinical and pharmacological properties of praziquantel, since a vast literature on these topics exists (for a review of schistosomiasis morbidity, see Gryseels, 1989; for a review of praziquantel therapy, see Kumar and Gryseels, 1994). Schistosomiasis is estimated to infect 200 million people in the world today, with an exposed population of about 600 million people, and occurs mainly in rural populations in frequent contact with freshwater. The disease is endemic in 74 tropical countries, and involves five species of schistosome worms: Schistosoma mansoni, S. haematobium, S. japonicum, S. intercalatum, and S. mekongi. Praziquantel is effective treatment for all five species and for both major types of morbidity (urinary lesions for S. haematobium, and hepatic lesions for the other species). The spread of schistosomiasis is often associated with water resource development projects (dams and irrigation schemes) that create new habitats for the snail vectors through ecosystem changes and alter human behaviour and settlement patterns in ways that increase exposure to the parasite (Hunter et al., 1993).

Praziquantel was the result of collaborative work between two German pharmaceutical manufacturers: Bayer A.G., Leverkusen, and E. Merck, Darmstadt. The anthelminthic activity of pyrazinoisoquinoline derivatives was discovered in 1972 in the laboratories of Bayer, and was followed up by J. Seubert and others at E. Merck (Andrews, 1981; Seubert et al., 1977a). Praziquantel’s curative efficacy against a broad spectrum of platyhelminths pathogenic to man was confirmed in testing during the following years (Wegner, 1984). The compound was patented in Germany in December 1973, and in the United States of America in 1977 (Seubert et al., 1977b). Praziquantel became available in Europe after 1978 (King and Mahmoud, 1989), and generally available on the international market in the 1980s. Table 2.1 presents data on Bayer/E. Merck’s registration of praziquantel patents, along with the estimated patent expiry dates.

Table 2.1: Bayer/E. Merck’s praziquantel patents

Country

Registration number

Expiration date

Argentina

208715

1992: 28 February

Australia

485552

1990: 16 December

Belgium

823400

1994: 16 December

Canada

1036606

1995: 15 August

Denmark

141845

1994: 16 December

Egypt


1984: 16 December

France

7441356

1994: 16 December

Germany

2302539

1991: 17 December

Greece

60708

1989: 17 December

Guatemala

3221

1994: 10 April

Hong Kong

133/79

1994: 12 November

Iran

18749

1994: 16 December

Ireland

40124

1990: 18 November

Israel

46162

1994: 29 November

Japan

1194423

1994: 17 December

Kenya

2946/79

1994: 12 November

Luxembourg

71204

1994: 29 October

Morocco

16807

1994: 9 December

New Zealand

176193

1990: 12 December

Nigeria

3044

1994: 14 December

Norway

142304

1994: 16 December

Pakistan

124888

1990: 18 November

Peru

1231

1983: 16 November

Philippines

14220

1998: 2 April

Poland

94074

1989: 16 December

Portugal

63084

1991: 27 April

Republic of Korea

8125

1992: 30 January

Romania

66907

1989: 13 December

Sweden

7415686-0

1994: 13 December

Singapore

74/1979

1994: 12 December

Spain

432974

1996: 15 October

South Africa

74/7259

1990: 12 November

Taiwan

12207

1992: 17 December

Tanzania

1969/1979

1994: 12 November

United Kingdom

1441554

1994: 12 November

USA

4001411

1994: 4 January

USSR

631070

1989: 17 December

Yugoslavia

41288

1997

Source: Bayer AG.

Praziquantel also has significant veterinary uses, and was approved in 1980 for such uses in the United States of America (Scrip, 1981), followed by approval and registration for human use in 1982 by the Food and Drug Administration (Scrip, 1981).

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