Ganglionic-blocking drugs

Kumar R, Reavill C, Stolerman IP (1987) Nicotine cue in rats effects of central administration of ganglion-blocking drugs, Br J Pharmacol 90 239-246 Lamb RJ, Preston KL, Schindler CW, Meisch RA, Davis F, Katz JL, Henningfield JE, Goldberg SR (1991) The reinforcing and subjective effects of morphine in post-addicts a dose-response study. J Pharmacol Exp Ther 259 1165-1173... 

The site of action of many blocking drugs has been shown to be at the associated ionic channel rather than at the receptor. Prolonged administration of ganglionic blocking drugs leads to the development of tolerance to their pharmacological effects. 

BASIC CLINICAL PHARMACOLOGY OF THE GANGLION-BLOCKING DRUGS... 

Some ganglion-blocking drugs. Acetylcholine is shown for reference. 

The ganglion-blocking drugs cause a predictable cycloplegia with loss of accommodation because the ciliary muscle receives innervation primarily from the parasympathetic nervous system. The effect on the pupil is not so easily predicted, since the iris receives both sympathetic innervation (mediating pupillary dilation) and parasympathetic innervation (mediating pupillary constriction). Ganglionic blockade often causes moderate dilation of the pupil because parasympathetic tone usually dominates this tissue. 

Thermoregulatory sweating is reduced by the ganglion-blocking drugs. However, hyperthermia is not a problem except in very warm environments, because cutaneous vasodilation is usually sufficient to maintain a normal body temperature. 

Basic Clinical Pharmacology of the Ganglion-Blocking Drugs... 

Because the effector cell receptors (muscarinic, <, and 6) are not blocked, patients receiving ganglion-blocking drugs are fully responsive to autonomic drugs acting on these receptors. In fact, responses may be exaggerated or even reversed (eg, norepinephrine may cause tachycardia rather than bradycardia), because homeostatic reflexes, which normally moderate autonomic responses, are absent. 

Another feature of all ganglion-blocking drugs was that the blood pressure fluctuated considerably from very low to high values. Despite careful adjustment of the dose, this fluctuation could not be done away with entirely. In the attempt to prevent the peaks of pressure the doses were elevated so that the patient at another time might be unable to stand erect because of postural hypotension. 

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