Nicotinic acid -

Ans. is 'a1 i.e., Increases HDL Nicotinic acid (Niacin)o There are three main type of lipases related to metabolism of lipoproteins -1. Lipoprotein lipase - Present in blood vessels and causes hydrolysis of tryglvceride content of VLDL and chylomicrones.2. Hepatic lipase - Converts IDL to LDL by hydrolysing the triglyceride content of IDL,Hormone sensitive lipase - Present intraceliularly in peripheral tissue and causes intracellular lipolysis by hydrolysing triglycerides.o Niacin (Nicotinic acid) inhibits intracellular lipolysis by inhibiting hormone sensitive lipase - |- intracellular FFA to liver -| triglyceride synthesis.o Niacin also increases the activity of lipoprotein lipase - | hydrolysis of VLDL triglyceride.o Nicotinic acid also reduces the production of VLDL in liver by inhibiting TG-synthesis - indirectly the VLDL degradation products IDL and LDL are also reduced,o Nicotinic acid is the most effective drug to raise HDL-CH.o Increased HDL is due to interference of direct pathway of HDL cholesterol to liver which involves apo-Al - Niacin decreases apo-A1 mediated hepatic clearance,o Nicotinic acid is used in type I, III, IV & V hyperlipoproteinemias.