Manforce 100 mg belongs to a class of medications known as PDE5 inhibitors (phosphodiesterase type 5 inhibitors). PDE5 is an enzyme that breaks down cyclic guanosine monophosphate (cGMP), a molecule that relaxes the smooth muscles in blood vessels, helping blood flow to the penis. When sexually stimulated, the body releases nitric oxide, which activates cGMP production. In men with ED, the activity of PDE5 reduces cGMP levels, leading to inadequate blood flow to the penis. By inhibiting PDE5, Manforce increases cGMP levels, allowing for enhanced blood flow and the ability to achieve and sustain an erection.