In Vitro Stability of Nomifensine in Plasma - Clinical Chemistry

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Patrick. Jaynes. Gordon. F. Kapke. In Vitro Stability of Nomifensine in. Plasma. To the Editor: After oral administration in man, unconjugated nomifensine. (Figure.
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4. I)as, K. M., and Dubin, R., Clinical pharmacokinetics of sulphasalazine. Clin. Pharmacokinet.

1,406-425 (1976).

5. A.ad Khan, A. K., and Truelove, S. C., Topics w Gastroentero/ogv, chapter 24, Hlackwell Scientific Publications, L(,ndon, England, 1976, p 367. 6. l)as, K. M., Eastwood, M. A., McManus, J. P. A., and Sircus, W., The metabolism of salicylazosulphapyridine in ulcerative Gut 14,631-641 (1973).

colitis.

J. W., Summers, R. W., Kern, F. .Jr., et al., A trial of sulphasalazine as adjunctive therapy in Crohn’s disease. Gastroent erologv 77, 887-897 (1979). S. Child, ,J. A., Brozovic, N. H., Dyer, D. L., 7. Singleton,

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of iron deficiency in padisease. Gut 14, 642-648

Patrick Jaynes Gordon F. Kapke Dept. Univ. Iowa

Pathol. of Iowa Hospitals City,

IA 52242

In Vitro Stability of Nomifensine in Plasma To the Editor:

After oral administration in man, unconjugated nomifensine (Figure 1) comprises 120 mg/L) and six

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bilirubin

‘20-

y’ -O.O2 ‘0.03 r’-O.75 p”O,OI

p

.-0.6l .0001

450-

a S

300-

2O SERUM OILIRU8N

Fig. 2. Serum hyperbilirubinemic serum bilirubin

OGOOmOO ‘g/L

Ca2+ concentrations in and control infants vs. concentrations

well infants

as controls had daily total and Ca2+ determinations on each of the first seven postnatal days. The infants were matched for gestational age and Apgar scores, two factors important in neonatal hypocalcemia. Ca2+ in serum decreased linearly with increasing bilirubin in all samples tested in vitro (Figure 1). No precipitation was seen at any of the bilirubin concentrations in the presence of serum pro-

serum bilirubin

teins. Although

Ca2

definitely

decreased

when bilirubin was added to serum, we were not able to detect a change in the residual binding capacity for bilirubin ascribable to increased calcium concentration. The residual binding capacity was unaltered even at a calcium concentration of 160 mg/L. When proteins were absent, increasing concentrations of bilirubin added to calcium in aqueous solution resulted in precipitation when the molar ratio of bilirubin to calcium exceeded 1:1. In the six infants with hyperbilirubinemia, serum hilirubin was highest (range 137 to 183 mg/L) and Ca2 lowest (range 31.6 to 41.7 mg/L) on postnatal days 3 to 6. In the six matched control infants, serum bilirubin was highest (range 90 to 112 mg/L) on days 3 to 5 and serum Ca2+ was lowest (range 36.2 to 39.0 mg/L) on days 2 to 3. The six hyperbilirubinemic infants had a significantly lower serum Ca2+ as compared to the six matched controls, 37.5 ± 0.4 (mean ± SEM) vs 39.6 ± 0.2 mg/L (paired t; p