Which medication is used for bradycardia from bufo toxin?

Bradycardia, which is a slower than normal heart rate, can occur as a result of toad poisoning, particularly from bufo toads that secrete toxins such as bufotenin. In cases of bradycardia induced by bufo toxins, atropine is the appropriate medication to use.

Atropine is an anticholinergic agent that works by blocking the effects of the neurotransmitter acetylcholine on the heart's pacemaker. It increases heart rate by inhibiting the parasympathetic nervous system's influence on heart function. This action counteracts the bradycardia caused by bufo toxins, improving the heart rate and helping stabilize the patient.

Other medications listed may have roles in different contexts but do not target the bradycardia associated with bufo toxin specifically. For instance, propranolol is a beta-blocker that can further reduce heart rate, diazepam is a tranquilizer frequently used for seizures or anxiety, and lidocaine is primarily an antiarrhythmic agent used to treat heart arrhythmias, not bradycardia. Thus, atropine stands out as the definitive therapeutic choice for bradycardia resulting from bufo toxin exposure.