Final answer:
Morphine is the drug that does not cause pupil dilation; instead, it often causes pupil constriction as it activates the parasympathetic nervous system, an opposite effect to drugs like methamphetamine, cocaine, and LSD that stimulate the sympathetic nervous system. The correct option is D.
Step-by-step explanation:
The question asks which of the following drugs does not cause pupil dilation. Pupil dilation, also known as mydriasis, can be caused by drugs that are sympathetic agonists, meaning they activate the sympathetic nervous system.
According to the information provided, norepinephrine and drugs that mimic its action, such as phenylephrine, bind to adrenergic receptors in the radial fibers of the iris and cause dilation.
Comparing this with the list of drugs provided: methamphetamine (meth), cocaine, and LSD can lead to the release of norepinephrine or mimic its effects, which results in pupil dilation as part of the 'fight-or-flight' response.
However, morphine has a different mechanism of action. It is an opioid that often causes pupil constriction, or miosis, by activating the parasympathetic nervous system. Specifically, it stimulates opioid receptors that can result in the release of acetylcholine, which is known to cause constriction of the pupil. The correct option is D.