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PLASMA-PARACETAMOL (ACETAMINOPHEN) MEASUREMENT
696 Our methods for measuring total paracetamol and free paracetamol in plasma are based on the methods of Welch and Conner and Chafetz et al.,2 respectively. We did measurements in eighteen cases of paracetamol overdose; there were 28 results in all because paracetamol levels were determined several times in some cases. One individual was admitted on three separate occasions. The results were:
*The data for free and total skewed to the left.
Fig. 2-IgM activities in sera of 7 patients.
Using the method described above, i.F. activities of 7 patients’ sera were titrated. H.E.K. cells infected with R.V.L. agent (after 5th passage) were used as antigen source. Serially diluted acute and convalescent sera and F.I.T.c.-conjugated rabbit anti-human IgG and IgM were used for indirect I.F. The results were shown in figs. 1 and 2. In acute sera, no IgG activities were detected at 4-fold dilution. However,1 patient’s serum had IgM activity at this dilution. In the convalescent phase, all 7 patients’ sera developed IgM response, but only 3 patients’ sera developed IgG response. Thus, the IgG-antibody response may not occur or may be delayed in some cases. This might suggest that the invasion of R.V.L. agent is localised at intestinal epithelium, so that only a very small amount of viral antigen is recognised by immunoTSUNEO MORISHIMA SHOICHI NAGAYOSHI TAKAO OZAKI SHIN ISOMURA SAKAE SUZUKI
Department of Pædiatrics, Nagoya University, 65 Tsurumaicho, Showaku, Nagoya, Japan
PLASMA-PARACETAMOL (ACETAMINOPHEN) MEASUREMENT
S:R,—There are several ways of measuring plasma-paracetamol. 1-6 However, some methods measure only "free" (unconjugated) paracetamol, while others measure the "total" paracetamol (free plus conjugated drug). Mrochek et aU established that the serum concentration of the glucuronide
conjugate was higher than that of the free drug 2 h after ingestion in the two subjects studied. Thus many of the methods used for measuring paracetamol may yield results which represent only a fraction of the paracetamol present in the plasma. Routh, J. I., Shane, N. A., Arredondo, E. G., Paul, W. D. Clin. Chem. 1968, 14, 882. 2. Chafetz, L., Daly, R. E., Schriftman, H., Lomner, J. J. J. pharm. Sci. 1971, 60, 463. 3. Gwilt, J. R., Robertson, A., McChesney, E. W. J. Pharm. Pharmac. 1963, 15, 440. 4. Prescott, L. F. ibid. 1971, 23, 807. 5. Welch, R. M., Conney, A. H. Clin. Chem., 1965, 11, 1064. 6. Brodie, B. B., Axelrod, J. J. Pharmac. exp. Ther. 1948, 94, 22. 7. Mrochek, J. E., Katz, S., Christie, W. H., Dinsmore, S. R. Clin. Chem. 1974, 20, 1086. 1.
paracetamol
were not
normally distnbuted, bemg
The results clearly demonstrated a considerable variation in the degree of conjugation of paracetamol, depending on the individual, the time after drug ingestion, the amount of drug ingested, and so on. Since those clinicians who treat their patients with cysteamine base their decision on whether to use cysteamine or not on the plasma-paracetamol concentration, it is clearly important to indicate which method is used, as was pointed out by Martin and Powell,s but it is even more important to indicate whether the figure given for plasma-paracetamol is for free or total drug. A result for free paracetamol can be obtained in about 15 min whereas a result for total paracetamol takes more than an hour because hydrolysis is required and this takes half an hour. Department of Pathology, Sefton General Hospital, 2HE
Liverpool L15
THOMAS A. WHITE
CYSTIC FIBROSIS IN SUMMER
SIR,—This summer has been a difficult one for the parents of many children with cystic fibrosis. The unusually hot weather has increased the risk of excessive salt loss in the sweat with the risk of hyponatraemia and hypokalaemia. However, there may be an added factor this year that has exacerbated the situation besides the heat. This is the first year that low-solute milks have been given as the norm to infants in Britain, following the concern over hypematraemia and the Government’s advice. Moreover, health visitors are now alert to the dangers of giving too much salt to normal young babies and advise mothers accordingly. There have been at least two infants with cystic fibrosis attending the University Hospital of Wales, where the use of low-solute milks was probably a factor in their becoming ill with heat prostration. It may well be advisable, especially in the summer, for infants with cystic fibrosis to be given cow’s milk or a cow’s milk equivalent rather than a low-solute milk Department of Child Health, Welsh National School of Medicine, Heath Park, Cardiff CF4 4XW
J.
R. SIBERT
PRIMARY LIVER-CELL CARCINOMA IN ACCRA
SIR,-Edington and Greenwood’s letter on primary livercell carcinoma in the savannah country of Northern Nigeria’ has prompted us to report our experience in Accra. It shows that cancer registries or surveys, particularly in Africa, which are based on histologically diagnosed cases only will grosslv underestimate the frequency of deep-seated cancers. In 1970 routine testing for alpha-fetoprotein in liver diseases was introduced to the Korle Bu Teaching Hospital. Accra, and this service was made available to the major hospi8.
Martin, P. J., Powell, J. P. Lancet, 1976, i, 536.
*The data for free and total skewed to the left.
Fig. 2-IgM activities in sera of 7 patients.
Using the method described above, i.F. activities of 7 patients’ sera were titrated. H.E.K. cells infected with R.V.L. agent (after 5th passage) were used as antigen source. Serially diluted acute and convalescent sera and F.I.T.c.-conjugated rabbit anti-human IgG and IgM were used for indirect I.F. The results were shown in figs. 1 and 2. In acute sera, no IgG activities were detected at 4-fold dilution. However,1 patient’s serum had IgM activity at this dilution. In the convalescent phase, all 7 patients’ sera developed IgM response, but only 3 patients’ sera developed IgG response. Thus, the IgG-antibody response may not occur or may be delayed in some cases. This might suggest that the invasion of R.V.L. agent is localised at intestinal epithelium, so that only a very small amount of viral antigen is recognised by immunoTSUNEO MORISHIMA SHOICHI NAGAYOSHI TAKAO OZAKI SHIN ISOMURA SAKAE SUZUKI
Department of Pædiatrics, Nagoya University, 65 Tsurumaicho, Showaku, Nagoya, Japan
PLASMA-PARACETAMOL (ACETAMINOPHEN) MEASUREMENT
S:R,—There are several ways of measuring plasma-paracetamol. 1-6 However, some methods measure only "free" (unconjugated) paracetamol, while others measure the "total" paracetamol (free plus conjugated drug). Mrochek et aU established that the serum concentration of the glucuronide
conjugate was higher than that of the free drug 2 h after ingestion in the two subjects studied. Thus many of the methods used for measuring paracetamol may yield results which represent only a fraction of the paracetamol present in the plasma. Routh, J. I., Shane, N. A., Arredondo, E. G., Paul, W. D. Clin. Chem. 1968, 14, 882. 2. Chafetz, L., Daly, R. E., Schriftman, H., Lomner, J. J. J. pharm. Sci. 1971, 60, 463. 3. Gwilt, J. R., Robertson, A., McChesney, E. W. J. Pharm. Pharmac. 1963, 15, 440. 4. Prescott, L. F. ibid. 1971, 23, 807. 5. Welch, R. M., Conney, A. H. Clin. Chem., 1965, 11, 1064. 6. Brodie, B. B., Axelrod, J. J. Pharmac. exp. Ther. 1948, 94, 22. 7. Mrochek, J. E., Katz, S., Christie, W. H., Dinsmore, S. R. Clin. Chem. 1974, 20, 1086. 1.
paracetamol
were not
normally distnbuted, bemg
The results clearly demonstrated a considerable variation in the degree of conjugation of paracetamol, depending on the individual, the time after drug ingestion, the amount of drug ingested, and so on. Since those clinicians who treat their patients with cysteamine base their decision on whether to use cysteamine or not on the plasma-paracetamol concentration, it is clearly important to indicate which method is used, as was pointed out by Martin and Powell,s but it is even more important to indicate whether the figure given for plasma-paracetamol is for free or total drug. A result for free paracetamol can be obtained in about 15 min whereas a result for total paracetamol takes more than an hour because hydrolysis is required and this takes half an hour. Department of Pathology, Sefton General Hospital, 2HE
Liverpool L15
THOMAS A. WHITE
CYSTIC FIBROSIS IN SUMMER
SIR,—This summer has been a difficult one for the parents of many children with cystic fibrosis. The unusually hot weather has increased the risk of excessive salt loss in the sweat with the risk of hyponatraemia and hypokalaemia. However, there may be an added factor this year that has exacerbated the situation besides the heat. This is the first year that low-solute milks have been given as the norm to infants in Britain, following the concern over hypematraemia and the Government’s advice. Moreover, health visitors are now alert to the dangers of giving too much salt to normal young babies and advise mothers accordingly. There have been at least two infants with cystic fibrosis attending the University Hospital of Wales, where the use of low-solute milks was probably a factor in their becoming ill with heat prostration. It may well be advisable, especially in the summer, for infants with cystic fibrosis to be given cow’s milk or a cow’s milk equivalent rather than a low-solute milk Department of Child Health, Welsh National School of Medicine, Heath Park, Cardiff CF4 4XW
J.
R. SIBERT
PRIMARY LIVER-CELL CARCINOMA IN ACCRA
SIR,-Edington and Greenwood’s letter on primary livercell carcinoma in the savannah country of Northern Nigeria’ has prompted us to report our experience in Accra. It shows that cancer registries or surveys, particularly in Africa, which are based on histologically diagnosed cases only will grosslv underestimate the frequency of deep-seated cancers. In 1970 routine testing for alpha-fetoprotein in liver diseases was introduced to the Korle Bu Teaching Hospital. Accra, and this service was made available to the major hospi8.
Martin, P. J., Powell, J. P. Lancet, 1976, i, 536.