Læknablaðið : fylgirit - 01.05.1978, Qupperneq 65

were related to the presence of other drugs in
plasma.
It appears from the present study that
naproxen can be used, with the same indications
and contra-indications, in patients with a reduced
GFR as in other patients. Thus the drug should
be avoided in patients with gastrointestinal
irritation or with a clinical bleeding tendency.
With routine dosage of napraxen patients with an
impaired renal function accumulate 6-des-methyl
naproxen in plasma but this is not likely to
cause side effects as the latter substance has
little pharmacological activity (7) and seems to
be highly untoxic (8).
What is the probable explanation for the
apparently shorter biological half-time of naproxen
in patients with uremia? - As for many other
drugs which are organic acids (9), the binding of
naproxen to plasma proteins is decreased in renal
failure. More free napraxen would then be avail-
able for des-methylation in the liver. The con-
centration of 6-des-methyl naproxen is then
likely to rise in piasma as this metabolite is
eliminated from plasma by the kidneys.
MEAN VALUES OF NAPROXEN AND METABOLITE
BEFORE AND AFTER DIALYSIS
3 patients NAPROXEN METABOLITE
Dose: 250 mg x 2 Before After Before Af ter
2-3 cycles (24 - 36 hours) 22.3 25.0 13.0 10.7
9-10 cycles (108-120 hours) 26.3 43.7 18.3 13.7
Patient MJ Naproxen pg/ml Metabolite pg/ml
Before D After D. Before D.' After D.
3 dose cycles 13 22 16 I 29
9 dose cycles 36 - 36 -
12 dose cycles (24^ after dose) 6 5 20 16 1
IMPORTANT DRUG TREATMENT IN PATIENTS OF THE TRIAL
MJ VH KGA HN RO EG
Aluminium hydroxide X X X X
Calcium-polystyrene X
Dicoumarol X
Digoxin/digitoxin X X X X
Diazepam/nitrazepam X X
Fentiazine/tricyclic X X
Dicloxacillin X
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