Lupride is the brand name; the name of medicine is leuprolide which is actually meant for the treatment of advanced cancer of prostate in men. It is also sometimes used in endometriosis.
If the medicine is not given early on during the menstrual cycle, then the months cycle is not missed and the following period is missed. This may explain the status in your case.
Lupride should not be used on a long term basis due to increased risk of osteoporosis (thinning of bones).