The discover of a new drug is given a patent for 20 years. After expiry, other manufacturers can make the same drug under a different brand name. If you know the generic name of the drug, you can buy the generic brand (instead of the original brand) at a lower cost.
Generic name Proprietary name General use
Paracetamol Panadol pain and fever
Diclofenac sodium Voltaren pain and swelling
Mefenamic acid Ponstan "
Chlorphenamine Piriton runny nose, rashes, itch, allergy
Loratadine Clarityne "
Cetirizine Zyrtec "
Cimetidine Tagamet gastric, heartburn, stomach ulcer
Omeprazole Losec "
Glocosamine Viartril-S joint supplement
Amoxicillin Augmentin antibiotic
Isotretinoin Roaccutane acne
Atenolol Tenormin high blood pressure
Prazosin Minipress "
Nifedipine Adalat LA high blood pressure, angina
Frusemide Lasix diuretic
Simvastatin Zocor cholesterol