Merck & Co., Inc. (NYSE:MRK) announced a deal to hand over its CGRP migraine drugs to Allergan PLC (NYSE:AGN) for $250 million, half of which is to be paid upfront in cash.

Merck has been in the competition for migraine drugs for a noteworthy period but recently decided to leave the race to the others to pace its focus elsewhere. The company will hand over two calcitonin gene-related peptide receptor antagonists. They are migraine treatment and prevention drugs that have been undergoing trials.

The transfer will give the acquiring firm the rights to carry out phase III trials for theMK-1602 oral drug once it receives authorization from the FDA. The trials are expected to begin in 2016. Allergan will also take over the MK-8031 drug that is on its way to Phase II trials. Merck expects to receive the remaining half of the deal by April next year. The two firms have also elected to include royalties and milestone deals though they have not yet released further details.

Patients suffering from severe migraines have been taking triptans to deal with their situations. Triptans constrict blood vessels in the brain to relieve the pain. Unfortunately not many patients respond to this type of treatment. Drug researchers have been trying a different approach where they intend to create a drug that can restrict CGRP receptors. Currently, the research involves the oral drug because its administration stands to be more preferred over other methods.

Merck had experienced some roadblocks in the past with a migraine treatment drug in 2012. The test subject experienced signs of liver failure, and the drug trials had to be stopped. So far, the recent drugs have not exhibited such side effects. A few other drug manufacturers are also researching with CGRPs. Amgen, Inc. (NASDAQ:AMGN) recently announced that it is already in 52 weeks of therapy with 70 mg of AMG334 and the results are good. The phase II trials revealed that its test subjects have experienced a 4.9 decline in the number of migraines experienced per month.