Are azithromax tablets still efficacious after expiration date? how long is the extended shelf life?

If stored properly, almost all drugs are safe and effective well after their expiration dates. The date indicates the amount of time that has been tested, but usually they just didn't test longer and therefore can't guarantee it's OK. But probably it would be fine. However, it usually isn't smart to self treat for any infection: get medical care before any self treatment with antibiotics.