I've tried...but it's difficult to find contact information for anyone in customs. The only phone number I have found that is an english line has a full mailbox. While I am able to communicate in spanish on a basic level, I don't think I am able to have this conversation in spanish effectively.
I did find this statement on the Costa Rica embassy page just last night:
"If you need to take your personal medicine while traveling to Costa Rica, please consider the following:
Carry just the necessary quantity, which is the quantity normally used by a person having your health problem.
You should have a prescription or a written statement from your doctor, specifying that the medicine is being used under his/her control and that you need it for your physical health.
Have the medicines labeled or properly identified."
I think it will be fine. A week of relaxing on a Costa Rican beach may be the best medicine anyway