Final answer:
The correct sign of atropine overdose in a child is an increased heart rate. The antidote for atropine poisoning is a muscarinic agonist like pilocarpine. Anti-anxiety effects are commonly produced by benzodiazepines, which are not related to atropine.
Step-by-step explanation:
The probable signs of atropine overdose include increase in heart rate. Atropine is a standard anticholinergic drug that can cause symptoms indicative of anticholinergic syndrome. Gastrointestinal smooth muscle cramping (A), increased gastric secretion (C), pupillary constriction (D), and urinary frequency (E) are contrary to the expected effects of atropine, an antimuscarinic agent. The signs of atropine poisoning typically would be those of sympathetic stimulation rather than parasympathetic effects suggested by these options.
Therefore, the correct answer is (B) Increased heart rate, because atropine blocks the action of the parasympathetic nervous system, which among other functions, normally decreases the heart rate. Other signs of atropine overdose would also include dilated pupils, dry mouth, and constipation due to decreased secretions and motility.
The antidote for atropine poisoning is a muscarinic agonist, with pilocarpine being a specific example as it can reverse the symptoms by stimulating the muscarinic receptors that have been blocked by atropine.
When discussing drugs with anti-anxiety effects, a different class of medications, such as benzodiazepines, would typically be referenced. These medications enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA), which helps induce a calming effect.