OPIUM. - 195 



pure alkaloid, that only a few points of difference require to 

 be noticed. These depend upon two principal circumstances : 

 (1) Opium, being much less soluble than the pharmacopceial 

 preparations of morphia, is more slowly absorbed, and thus 

 acts less quickly than morphia, whilst its effects are more 

 lasting, and its immediate local action on the intestines 

 decidedly more marked. (2) Several of the constituents of 

 opium possess more or less convulsant action (thebain, codeia, 

 narcotin), morphia none (in man) ; the latter has therefore a 

 somewhat more sedative influence than the entire drug. The 

 effect of opium on the skin is also less marked in morphia. 

 Unless there be some special reason to the contrary, morphia 

 is generally to be preferred to opium in practice, as being of 

 definite composition (whilst the crude drug is very variable), 

 more rapid in action, readily administered hypodermically, 

 whilst the dyspeptic and constipating effects of the drug 

 are less marked. Opium is to be preferred in intestinal and 

 abdominal diseases such as diarrhoea, obstruction, peritonitis, 

 hernia, because it reaches the bowel; in delirium tremens 

 and mental disorder, because its action is more continued ; 

 in diabetes, because it contains codeia ; for combinations with 

 quinine or calomel, and as a diaphoretic, because it prevents pur- 

 gation and lowers fever ; in astringent enemata, from its action 

 on the bowel; and for local applications, e.g. to the con- 

 junctiva, because less irritant than the alkaloid. The relative 

 strength of opium to morphia is about 20 or 30 to 100, \ or 

 |tol. 



2. Codeia. This alkaloid appears to excite the cord more 

 than morphia, and to depress the convolutions less, so that 

 muscular tremors may follow and exceed the sedative influence. 

 Codeia, in ^-gr. doses cautiously increased, markedly reduces 

 the amount of sugar in diabetes, appearing to act as an 

 alterative to the nervous system, and thus to cure (not simply 

 relieve) the disease in some instances. 



3. Narcotin, which is so large a constituent of opium, is 

 probably often impure from an admixture of morphia. By 

 some authorities it is considered to be hypnotic, by others con- 

 vulsant. It is not used. 



4. Narce'in probably acts like morphia, and is not employed 

 medicinally. 



5. Thebain is a convulsant, almost like strychnia, but is not 

 used. 



6. Opianin, cryptopia, metamorphia, and possibly papa- 

 verina, act like morphia. Porphyroxin and laudanin act like 

 codeia. 



The action of meconic acid is doubtful. 



