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 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. Here are a few guidelines for Rx's: The length of time that a prescription is good for depends on the medication and the doctor.