Unwanted effects of digitalis drugs such as digitoxin may include?

The unwanted effects of digitalis drugs like digitoxin primarily relate to their impact on the cardiovascular system. Digitalis can lead to irregularities in heart rhythm, which may present as an irregular or slow heartbeat, also known as bradycardia. Additionally, nausea and weakness are common side effects, reflecting the drug's influence on both gastrointestinal and muscular systems. These symptoms are crucial to monitor in patients taking digitalis, as they can indicate toxicity or adverse reactions that may require medical attention.

The other options listed, while they describe possible side effects associated with different medications or conditions, do not specifically pertain to the known side effects of digitalis drugs. Parkinsonian symptoms and seizures are typically associated with neurological disorders or side effects from certain antipsychotic medications, but not digitalis. Similarly, symptoms like inability to sleep, nervousness, and restlessness are more commonly related to stimulant medications or anxiety disorders rather than digitalis. Lastly, constipation, tarry stools, and indigestion can be related to a variety of conditions or medications, but these are not characteristic side effects associated with digitalis therapies.