When it comes to transporting medicines, if you are diabetic for example, it is recommended that you keep your insulin in its original packaging. It will make it easier for the customs to identify the drug and the prescribing doctor.
It is strongly recommended for you to bring a certificate from your MD stating what you need (e.g. insulin and injectional devices). Show this certificate as you pass through the security check and the customs. It is recommended to have this certificate printed in English in order for the airport staff on your return trip to understand it. Some countries only demand a certificate from your pharmacy.
Store the medicine in your carry-on luggage.