Top pharmaceutical companies in the U.S. and Europe have said they are halting recruitment for clinical trials in Russia, while continuing to send medicine and other health supplies to help those in need.

Drugmakers including Pfizer Inc., Johnson & Johnson, Merck & Co., Roche Holding Ag and Bristol Myers Squib Co. are seeking to strike a balance between international opprobrium over Russia’s invasion of Ukraine and the needs of sick patients.

New York-based Pfizer said on Monday that it would no longer start new clinical trials in Russia and that it would donate all profits from its subsidiary in the country to Ukraine relief causes.