Generic prescription drugs are available only when the patent for the original brand name drug has expired. The patents for many popular brand name drugs have recently expired. However, if a generic is not available, there may be an alternative medication in the same pharmaceutical class that is less expensive or that does have a generic equivalent. Ask your physician if such an alternative would be right for you.
Most pharmacies carry primarily "A" rated generics. Non- "A" rated generics are usually used only for conditions that are not life-threatening (such as decongestants, etc.), but the only way to know for sure is to ask your pharmacist.