Well, you are eating buckwheat, right? Well lets put it this way, your medication likely contains the same amount of starch as 4 buckwheat groat kernels, or maybe less starch than 2 pieces of rice. Its so minute its not worth worrying about.
However, prescription medications are worth worrying about because they cause all sorts of imbalances in the body. Almost all prescription medications prevent the liver from detoxing properly and this is concerning if you are trying to improve your health. Additionally, prescription medications have all sorts of side effects such as dehydration, brain fog, constipation, etc. depending on the medication you use. Additionally, they may cause hormonal imbalances that are hard to remedy in the long term.