I am taking 40 mg of fluoexetine for my depression. i have missed a few weeks of my meds. is there a safe way to catch up?

Not "catch up": There's not really a way to "catch up" on past doses of fluoxetine. If you've missed a few weeks of taking it -- and that's all you're prescribed -- you could just re-start your regular prescribed dosage beginning tonight. I'd also suggest telling your physician what's happened. Hopefully your depression has not relapsed in the interim.

Prozac (fluoxetine) for depressio: You can start with 20 mg for a week, then continue with 40. Prozac (fluoxetine) has the longest half life among the antidepressants.