My guess is like a lot of meds. Missing a dose every once in awhile does not usually have disastrous effects. Just don't miss too often. It's not like it is blood pressure medicine or transplant organ anti-rejection medicine where missing a dose could have devastating results.

(disclaimer: I am not a physician, so I do not speak with educated authority here. Just out of my personal experience. Consult your prescribing physician with any concerns you may have.)