In all patients receiving penicillamine, it is important that Depen (Penicillamine) be given on an empty stomach, at least one hour before meals or two hours after meals, and at least one hour apart from any other drug, food, or milk. Because penicillamine increases the requirement for pyridoxine, patients may require a daily supplement of pyridoxine (see ).
Determination of 24-hour urinary copper excretions is of greatest value in the first week of therapy with penicillamine. In the absence of any drug reaction, a dose between 0.75 and 1.5 g that results in an initial 24-hour cupriuresis of over 2 mg should be continued for about three months, by which time the most reliable method of monitoring maintenance treatment is the determination of free copper in the serum. This equals the difference between quantitatively determined total copper and ceruloplasmin-copper. Adequately treated patients will usually have less than 10 mcg free copper/dL of serum. It is seldom necessary to exceed a dosage of 2 g/day. If the patient is intolerant to therapy with Depen (Penicillamine) , alternative treatment is trientine hydrochloride.
In patients who cannot tolerate as much as 1 g/day initially, initiating dosage with 250 mg/day, and increasing gradually to the requisite amount, gives closer control of the effects of the drug and may help to reduce the incidence of adverse reactions.
The usual dosage of Depen (Penicillamine) in the treatment of cystinuria is 2 g/day for adults, with a range of 1 to 4 g/day. For pediatric patients, dosage can be based on 30 mg/kg/day. The total daily amount should be divided into four doses. If four equal doses are not feasible, give the larger portion at bedtime. If adverse reactions necessitate a reduction in dosage, it is important to retain the bedtime dose.
Initiating dosage with 250 mg/day, and increasing gradually to the requisite amount, gives closer control of the effects of the drug and may help to reduce the incidence of adverse reactions.
In addition to taking Depen (Penicillamine) , patients should drink copiously. It is especially important to drink about a pint of fluid at bedtime and another pint once during the night when urine is more concentrated and more acid than during the day. The greater the fluid intake, the lower the required dosage of Depen (Penicillamine) .
Dosage must be individualized to an amount that limits cystine excretion to 100-200 mg/day in those with no history of stones, and below 100 mg/day in those who have had stone formation and/or pain. Thus, in deter-mining dosage, the inherent tubular defect, the patient’s size, age, and rate of growth, and his diet and water intake all must be taken into consideration.
The standard nitroprusside cyanide test has been reported useful as a qualitative measure of the effective dose*:
* Lotz, M., Potts, J.T. and Bartter, F.C.: : 521, August 28, 1965 (in Medical Memoranda).
Add 2 mL of freshly prepared 5 percent sodium cyanide to 5 mL of a 24-hour aliquot of protein-free urine and let stand ten minutes. Add 5 drops of freshly prepared 5 percent sodium nitroprusside and mix. Cystine will turn the mixture magenta. If the result is negative, it can be assumed that cystine excretion is less than 100 mg/g creatinine.
Although penicillamine is rarely excreted unchanged, it also will turn the mixture magenta. If there is any question as to which substance is causing the reaction, a ferric chloride test can be done to eliminate doubt: Add 3 percent ferric chloride dropwise to the urine. Penicillamine will turn the urine an immediate and quickly fading blue. Cystine will not produce any change in appearance.
When treatment with Depen (Penicillamine) has been interrupted because of adverse reactions or other reasons, the drug should be reintroduced cautiously by starting with a lower dosage and increasing slowly.
Changes in maintenance dosage levels may not be reflected clinically or in the erythrocyte sedimentation rate for two to three months after each dosage adjustment.
Some patients will subsequently require an increase in the maintenance dosage to achieve maximal disease suppression. In those patients who do respond, but who evidence incomplete suppression of their disease after the first six to nine months of treatment, the daily dosage of Depen (Penicillamine) may be increased by 125 mg or 250 mg/day at three-month intervals. It is unusual in current practice to employ a dosage in excess of 1 g/day, but up to 1.5 g/day has sometimes been required.
In the rheumatoid patient, migratory polyarthralgia due to penicillamine is extremely difficult to differentiate from an exacerbation of the rheumatoid arthritis. Discontinuance or a substantial reduction in the dosage of Depen (Penicillamine) for up to several weeks will usually determine which of these processes is responsible for the arthralgia.
Depen (Penicillamine) ® (penicillamine tablets, USP) Titratable Tablets: 250 mg scored, oval, white tablets coded with 37-4401; available in bottles of 100 (NDC 0037-4401-01).
Storage: Store at controlled room temperature 20°–25°C (68°–77°F). Protect from moisture.
Dispense in a tight container.
Manufactured by: Patheon Pharmaceuticals Inc. Cincinnati, OH 45237
For: Meda Pharmaceuticals Meda Pharmaceuticals Inc. Somerset, New Jersey 08873-4120
©2009 Meda Pharmaceuticals Inc.
70018452 Rev. 4/09
