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PHARMACOLOGIA.|| ON THE| OPERATIONS OF MEDICINAL BODIES,| AND ON THE| CLASSIFICATIONS FOUNDED ON THEM.

“Medicos tandem tædet et pudet, diutius garrire de Remediis, Specificis, et Alexipharmicis, et cæteris, nisi eorum naturam et modum quo prosint, quodammodo ostendere et explanare possint.”

Conspect. Med. Theor.

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Medicinal Substances are those bodies, which, by due administration, are capable of producing certain changes in the condition of the living system, whereby its morbid actions may be entirely removed, or advantageously controlled.

In adopting this definition we intentionally exclude those alimentary substances which are more immediately subservient to the support of life, and to the repair of that diurnal waste, which the exercise of its functions so inevitably occasions.

It has been generally supposed, that substances whose application does not produce any sensible action upon the healthy system, cannot possess medicinal energy; and, on the contrary, that those bodies which occasion an apparent effect in health, must necessarily prove active in the cure or palliation of disease. Under certain limitations we may perhaps venture to assent to this general proposition; but it cannot be too forcibly or too frequently impressed upon the mind of the medical practitioner, that Medicines are frequently but relative agents, producing their effects in reference only to the state of the living frame; we must therefore concur with Sir Gilbert Blane in stating, that the virtues of Medicines cannot be fairly essayed, nor beneficially ascertained, by trying their effects on sound subjects, because that particular morbid condition does not exist which they may be exclusively calculated to remove;^[127] thus in certain states of debility, Tonics may excite the system when languid, by their sympathetic influence upon the primæ viæ, while in a robust condition of the body, the effects of the same agents may be wholly inappreciable.