376 ASCORBIC ACID 



arthritis. Subperiosteal hemorrhages in infants may also suggest arthritis, 

 but careful examination will demonstrate that the subperiosteal hemor- 

 rhages do not involve the joint. 



In children the ecchymoses and joint hemorrhages common to hemo- 

 philia may be confused with scurvy. However, the clotting time of the 

 hemophiliac is usually long and the serum prothrombin concentration high. 



As has been demonstrated, laboratory tests for ascorbic acid in serum 

 or urine are helpful in eliminating scurvy from consideration if any of this 

 vitamin is found. Saturation tests or tolerance tests indicate only satura- 

 tion or unsaturation of the tissues which may exist for months before 

 scurvy appears. A level of mg. % in the white cell-platelet layer of the buffy 

 coat is the only laboratory evidence of scurvy or the immediate prescor- 

 butic state. 



X. Pharmacology 



RICHARD W. VILTER 



Ascorbic acid is a white, odorless crystalline substance, molecular weight 

 176.06. In the dry state it is reasonably stable in air, but it rapidly de- 

 teriorates in aqueous solution in the presence of air. It is heat labile. One 

 gram is soluble in 3 ml. of water, 25 ml. of alcohol, 50 ml. of absolute 

 alcohol, or 100 ml. of glycerin. It is insoluble in benzene, chloroform, ether, 

 petroleum ether, or fat. The l isomer is the physiologically active form. 

 Reduced ascorbic acid comes to equilibrium with its oxidation product, 

 dehydroascorbic acid, also antiscorbutic, which is converted above pH 4 

 to 2 , 3-diketogluconic acid and thence to oxalic and L-threonic acids. Either 

 ascorbic acid or its sodium salt may be given orally or parenterally. The 

 sodium salt is preferable for intramuscular injection because it causes less 

 local pain than the acid substance. Ascorbic acid is available in 15-, 25-, 

 50-, 100-, and 250-mg. tablets for oral use and as the sodium salt in 100-, 

 250-, 500-, and 1000-mg. ampules for intravenous or intramuscular use. 

 Within very wide limits of dosage there are no toxic effects, although, as 

 with any chemical compound which is given intravenously, very occasional 

 anaphylactoid reactions may occur. 



After either oral or parenteral administration, ascorbic acid is excreted 

 rapidly in the urine of persons whose tissues are saturated with it. It appears 

 in the urine most rapidly after being given by the intravenous route. It is 

 excreted by the glomeruli and resorbed by the tu})ulos. Tm for the tubules 

 is reported to be 1.2 to 2.1 mg. per 100 ml. of glomerular filtrate (the renal 



