I have been using Lopid (Gemfibrozil) and my cholesterol values have gotten worse. Is there any specific reason?

This med is used to lower triglycerides which are another risk factor for vascular disease. So they will not directly lower the cholesterol, so you should look at your lipid profile and you should see improvement in your triglycerides and in your LDL/HDL ratio. Also even though you are taking a medicine to help with your lipids you need to maintain a low fat diet.