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ITP - Chronic Immune Thrombocytopenic Purpura RX     See ITP_drug2007.pdf

Chronic ITP is the most common cause of thrombocytopenia in adults. It is due to platelet destruction by an autoantibody.

INITIAL TREATMENT
No treatment is indicated unless the platelet count is less than 25,000 to 30,000 mm3 .
Patients are treated initially with prednisone; if there is no response or relapse occurs on tapering of the prednisone, splenectomy is indicated.
Patients should be immunized with pneumococcal, meningococcal, and Haemophilus influenzae vaccines before surgery to prevent subsequent severe infections with these organisms, which occur more commonly in splenectomized patients.
Therapy with corticosteroids and splenectomy results in the cure of about 70% of patients.

REFRACTORY CASES
The treatment of ITP that is refractory to prednisone and splenectomy is more complex. Therapy can be arbitrarily divided into four levels according to the severity of the disease, the side effects associated with the treatment, and the evidence that the treatment might work. The treatments should generally be given in the order and for the indications given here.
In the event of severe mucosal bleeding, concurrent therapy with IGIV plus platelets or high-dose methylprednisolone plus platelets may be required (see "Emergency Treatment").

Level 1 Treatments : for a platelet count less than 30,000 per mm3 .

• STANDARD-DOSE PREDNISONE.
  Give 1 mg per kg PO daily; taper to the lowest dose allowing a platelet count higher than 30,000 per mm3 . Continue if that dose is 10 mg or less per day.
• VINCRISTINE (ONCOVIN).*
  Give 2 mg IV every week. Stop if there is no response after the second dose. Do not give more than 4 to 6 doses, or peripheral neuropathy will occur.
• PULSED DEXAMETHASONE.
  Give 40 mg PO daily for 4 days; repeat every 4 weeks for a total of six courses. Stop after three courses if there is no response or if relapse occurs during treatment.
• DANAZOL (DANOCRINE)* PLUS PREDNISONE.
  Give danazol, 200 mg PO four times a day, with prednisone, 1 mg per kg PO daily. Taper the prednisone when the platelet count reaches safe levels or after 6 weeks. The danazol should be continued for at least 4 to 6 months before it is abandoned. If the platelet count becomes normal, continue danazol at full doses for 1 year, and then taper by 200 mg per day every 3 months to the lowest dose allowing safe platelet counts.
• DAPSONE.*
  Give 75 to 100 mg PO daily. Continue for 8 weeks, and then stop if there is no response. In responsive patients, therapy must be continued or relapse will occur. Dapsone may cause severe hemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient patients, so G6PD status should be tested before this agent is used.
• COLCHICINE.*
  Give 0.6 mg PO daily, and increase the dose every 2 weeks to a maximum of 0.6 mg PO three times daily. Diarrhea often limits dosage. Continue for 3 months, and stop if there is no response. In responsive patients, therapy must be continued, or relapse will occur.
  Efficacy of colchicine alone or in combination with vinca alkaloids in severe corticoid-resistant thrombocytopenic purpura: six cases -   AJ Med  Dec. 1999;107:645  -  Bernard Bonnotte  (Table)

Level 2 Treatments: only if the platelet count is less than 10,000 to 15,000 per mm3 or if mucosal bleeding is present.

• STAPHYLOCOCCAL-A IMMUNOADSORPTION COLUMN.
  Give a maximum of six treatments (three times a week for 2 weeks) per the manufacturer's instructions. Toxicity may be substantial, and some experts do not recommend this treatment.
• CYCLOPHOSPHAMIDE (CYTOXAN).*
  Give 150 mg PO daily for 8 weeks; adjust the dose if neutropenia occurs. The patient must drink 2 quarts of fluid daily to prevent hemorrhagic cystitis. If a complete response occurs, continue at the full dose for 3 months, and then stop the drug. If no response occurs within 8 weeks, stop the drug.
• AZATHIOPRINE (IMURAN).*
  Give 150 mg PO daily for 6 months (responses often occur slowly). If a complete response occurs, continue at full doses for 18 months, and then stop therapy. If no response occurs in 6 months, stop therapy.
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Level 3 Treatments: Because of the more serious side effects, these treatments are reserved for patients whose ITP is refractory to the level 1 and 2 treatments and who have life-threatening symptoms or extremely low platelet counts (less than 5000 per mm3 ).

• PULSED CYCLOPHOSPHAMIDE (CYTOXAN).*
  Give 1.0 to 1.5 grams per m2 IV every 4 weeks for a total of four courses. The patient must drink at least 2 quarts of fluid daily for the 3 days after each treatment or must receive comparable fluids IV to prevent hemorrhagic cystitis. Antinauseants should be given.
• COMBINATION CHEMOTHERAPY.
  Several "lymphoma-type" regimens have been used. This treatment should be given after consultation with a hematologist or oncologist familiar with such regimens. No specific regimen has been found superior.

Level 4 Treatments: These treatments are in the "when all else fails" category, because experience with them is limited, response rates are low, or their expense and frequency of administration weigh against their use.

• INTERFERON ALFA-2B (INTRON A).*
  Give 3 million units subcutaneously three times a week for 4 weeks. Responses may occur during therapy or after the drug is stopped. For patients showing response, consideration should be given to long-term treatment, although there is minimal experience with this approach.
• IV IMMUNE GLOBULIN. (as Sandoglobulin)
  Some patients in whom all other treatments fail show response to IVIG. Start at 0.4 g/kg/day single IV infusion for 2-5 consecutive days; if an adequate response does not result, the dose can be increased to 0.8-1.0 g/kg as a single infusion. . Responses are temporary, lasting 1 to 6 weeks. This therapy is extremely expensive and inconvenient but may be the only option in some patients.
• VINBLASTINE (VELBAN).*
  Some patients with ITP who respond to vincristine also respond to this agent; responses are temporary, however, and the treatment is inconvenient. Give 5 to 10 mg IV weekly. Peripheral neuropathy is rare, and this drug can be given for long periods to patients who show response.
• CYCLOSPORINE (SANDIMMUNE).*
  Give 1.25 to 2.5 mg per kg PO twice daily. Kidney damage may occur, so serum creatinine and cyclosporine levels must be monitored. Reported responses have been short despite continued treatment.

EMERGENCY TREATMENT: In patients with severe mucosal bleeding,
give one of the following:

1. IVIG (IV Immune Globulin as Sandoglobulin), 1.0 gram per kg IV, followed by a platelet transfusion (a single plateletpheresis or 6 to 8 units of random platelets) or
2. Methylprednisolone (Solu-Medrol), 1.0 gram IV daily for 3 days, and give platelets after the first dose.

REF:
Conn's Current Therapy 50th Ed. 1998
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