In this case you can take the 120 er/myl twice daily instead of the 240 er/myl daily. People should be very careful with verapamil. I have seen someone erroneously think that taking 3 x 80mg immediate release verapamil is the same as 240mg er. They ended up in the special cardiac unit for a day. You can always call your local pharmacist for advice
120 is just half a dose of your regular. If you were to take two 120's this would equal out to be 240. If they are the same medication you can take two 120's and this would be like taking one 240 verapamil.