Introduction
Wilson's disease (hepatolenticular degeneration) is an
autosomal inherited metabolic defect resulting in an inability to maintain a
nearzero balance of copper. Excess copper accumulates possibly because the
liver lacks the mechanism to excrete free copper into the bile. Hepatocytes
store excess copper but when their capacity is exceeded copper is released into
the blood and is taken up into extrahepatic sites. This condition is treated
with a low copper diet and the use of chelating agents that bind copper to
facilitate its excretion from the body.
Clinical Summary
Forty-one patients (18 male and 23 female) between the ages
of 6 and 54 with a diagnosis of Wilson's disease and who were intolerant of
d-penicillamine were treated in two separate studies with trientine
hydrochloride. The dosage varied from 450 to 2400 mg per day. The average
dosage required to achieve an optimal clinical response varied between 1000 mg
and 2000 mg per day. The mean duration of trientine hydrochloride therapy was
48.7 months (range 2-164 months). Thirty-four of the 41 patients improved, 4
had no change in clinical global response, 2 were lost to follow-up and one
showed deterioration in clinical condition. One of the patients who improved
while on therapy with trientine hydrochloride experienced a recurrence of the
symptoms of systemic lupus erythematosus which had appeared originally during
therapy with penicillamine. Therapy with trientine hydrochloride was discontinued.
No other adverse reactions, except iron deficiency, were noted among any of
these 41 patients.
One investigator treated 13 patients with trientine
hydrochloride following their development of intolerance to d-penicillamine. Retrospectively,
he compared these patients to an additional group of 12 patients with Wilson's
disease who were both tolerant of and controlled with d-penicillamine therapy,
but who failed to continue any copper chelation therapy. The mean age at onset
of disease of the latter group was 12 years as compared to 21 years for the
former group. The trientine hydrochloride group received dpenicillamine for an
average of 4 years as compared to an average of 10 years for the non-treated
group.
Various laboratory parameters showed changes in favor of the
patients treated with trientine hydrochloride. Free and total serum copper,
SGOT, and serum bilirubin all showed mean increases over baseline in the
untreated group which were significantly larger than with the patients treated
with trientine hydrochloride. In the 13 patients treated with trientine
hydrochloride, previous symptoms and signs relating to d-penicillamine
intolerance disappeared in 8 patients, improved in 4 patients, and remained
unchanged in one patient. The neurological status in the trientine
hydrochloride group was unchanged or improved over baseline, whereas in the untreated
group, 6 patients remained unchanged and 6 worsened. Kayser-Fleischer rings improved
significantly during trientine hydrochloride treatment.
The clinical outcome of the two groups also differed
markedly. Of the 13 patients on therapy with trientine hydrochloride (mean duration
of therapy 4.1 years; range 1 to 13 years), all were alive at the data cutoff
date, and in the non-treated group (mean years with no therapy 2.7 years; range
3 months to 9 years), 9 of the 12 died of hepatic disease.
Chelating Properties
Preclinical Studies
Studies in animals have shown that trientine hydrochloride
has cupriuretic activities in both normal and copper-loaded rats. In general, the
effects of trientine hydrochloride on urinary copper excretion are similar to
those of equimolar doses of penicillamine, although in one study they were
significantly smaller.
Human Studies
Renal clearance studies were carried out with penicillamine
and trientine hydrochloride on separate occasions in selected patients treated
with penicillamine for at least one year. Six-hour excretion rates of copper
were determined off treatment and after a single dose of 500 mg of
penicillamine or 1.2 g of trientine hydrochloride. The mean urinary excretion
rates of copper were as follows:
| No. of Patients |
Single Dose Treatment |
Basal Excretion Rate
(μg Cu + + /6hr) |
Test-dose Excretion Rate
(μg Cu + + /6hr) |
| 6 |
Trientine, 1.2 g |
19 |
234 |
| 4 |
Penicillamine, 500 mg |
17 |
320 |
In patients not previously treated with chelating agents, a
similar comparison was made:
| No. of Patients |
Single Dose Treatment |
Basal Excretion Rate
(μg Cu + + /6hr) |
Test-dose Excretion Rate
(μg Cu + + /6hr) |
| 8 |
Trientine, 1.2 g |
71 |
1326 |
| 7 |
Penicillamine, 500 mg |
68 |
1074 |
These results demonstrate that SYPRINE is effective as a
cupriuretic agent in patients with Wilson's disease although on a molar basis it
appears to be less potent or less effective than penicillamine. Evidence from a
radio-labelled copper study indicates that the different cupriuretic effect
between these two drugs could be due to a difference in selectivity of the
drugs for different copper pools within the body.
Pharmacokinetics
Data on the pharmacokinetics of trientine hydrochloride are
not available. Dosage adjustment recommendations are based upon clinical use of
the drug (see DOSAGE AND ADMINISTRATION).
Last updated on RxList: 5/19/2009