AB, don''t forget to look at your timetable alongside the effective useage period of Chloroquine. As I recall, we decided not to carry malaria drugs because they''d expire before our arrival where we needed them in the W Caribbean. And that''s if we stowed them in the reefer, not in the med locker where ambient conditions are tougher on meds.
Also, don''t forget you can source drugs once you arrive. A good clinic in a city (e.g. G City in Guatemala) will have what you need...altho'' the source will determine how fresh the drug is.
We traveled inland in C America some, but not a lot. If you''re backpacking and bus touring, you may have more of a need for malaria preventitive meds but, for boaters, we found almost no one using them, even those that went up the Macraya River into VZ, visited Panama, or sailed thru the W Caribbean. But usually folks were quite diligent about insect screen useage; we sure were.