A nurse is reviewing the medical history of a client who has myasthenia gravis and is asking about starting neostigmine. The nurse should identify which of the following client conditions as a potential contraindication for cholinesterase inhibitor therapy?

A. Cataracts are not a contraindication for cholinesterase inhibitors like neostigmine. B. Hypertension is not a direct contraindication for cholinesterase inhibitor therapy, although caution may be exercised depending on the overall health status of the client. C. Hypothyroidism is not contraindicated for cholinesterase inhibitors; however, it should be managed appropriately. D. Peptic ulcer disease is a significant contraindication for cholinesterase inhibitors like neostigmine because these medications can increase gastric secretions and motility, potentially exacerbating ulcer conditions and leading to complications.