List of products in the National Drug Code with proprietary name . This medication is used to help prevent migraine. It is also used to treat a certain type of headache (episodic cluster headache). Galcanezumab-gnlm belongs to a class of drugs known as monoclonal antibodies. This medication may work by changing the amounts of certain natural substances in the brain. Using this medication can help improve your ability to concentrate and do your usual tasks.