1. (General Engineering) tungsten-electrode inert gas welding: a method of welding in which the arc is maintained by a tungsten electrode and shielded from the access of air by an inert gas. Compare MIG welding.
A prescription for a controlled drug is valid for 28 days from the date given on the prescription. usually six months unless it's a controlled i.e. morphine, pethidine and methadone. These medicines are often misused, so have stricter legal controls on their supply to prevent them being obtained illegally. A prescription for a controlled drug is valid for 28 days from the date given on the prescription.
Most of these answers are only partially correct or just PLAIN WRONG. If the Rx was written in July, it is still valid. Most Rx's are good for a year and NO Rx expires before 6 months unless the Dr. revokes it or no longer has a license to prescribe at the time you try to fill it. The length of time that a prescription is good for depends on the medication and the doctor.