Description
BackgroundTrimethoprim-sulfamethoxazole (TMP-SMX), also known as Septra, Bactrim, and cotrimoxazole, is a key antibiotic for prophylaxis and treatment of several HIV-related illnesses. It is the most effective prophylaxis and the first-line treatment for Pneumocystis jiroveci pneumonia (PCP). In addition, it is effective in preventing toxoplasmosis encephalitis in severely immunocompromised patients who have evidence of previous infection, and it is effective against certain bacterial infections. TMP-SMX also is quite inexpensive, which is a rarity in the world of HIV treatment. Because of its effectiveness and availability, it is used widely throughout the world. However, adverse reactions to TMP-SMX and other sulfa drugs occur in a high proportion of HIV-infected patients (roughly 25%), and such reactions may limit treatment. Desensitization to TMP-SMX should be considered when there are no reasonable or available alternatives and the patient has not experienced severe reactions (eg, Stevens-Johnson syndrome) to sulfa drugs. Several methods of desensitizing patients with previous reactions to TMP-SMX have been tried. These methods vary in starting dosage and length of dosage escalation, but success rates are around 80% in most cases and may be higher in those patients with <200 CD4 cells/µL. S: Subjective The patient reports a previous adverse reaction to sulfa drugs, such as erythema, pruritus, or rash. The patient has no history of anaphylaxis, Stevens-Johnson syndrome, or toxic epidermal necrolysis, and no reaction involving vesiculation, desquamation, ulceration, exfoliative dermatitis, etc. O: Objective CD4 count <200 cells/µL, or other important indication for TMP-SMX. A: Assessment Reaction to sulfa, possibly reversible with desensitization protocol. P: Plan Begin 9- to 13-day desensitization protocol, starting with pediatric oral suspension, which contains 40 mg of TMP and 200 mg of SMX per 5 mL (1 teaspoon). Gradually increase the dosage according to the protocol. If there is any question about the severity of a previous reaction, have the patient take the initial morning dose in the clinic so that the patient may be monitored for 3-4 hours before going home. (This assumes that emergency treatment, including IV access materials and IV fluids, antihistamines, and steroids, are readily available.) Treat with an antihistamine medication 1 day before starting the desensitization regimen and continue daily until the dose escalation is completed. More rapid desensitization protocols are available (see " References " below) for patients urgently needing treatment with TMP-SMX. Desensitization Regimen Use commercially available pediatric suspension (containing TMP 8 mg and SMX 40 mg per mL), followed by double-strength tablets, as follows: Table 1. Sulfa Desensitization Regimen Days Dosage (TMP/SMX) Volume or Tablet 1-3 3-6 5-9 7-12 9-10 and thereafter 8 mg/40 mg 16 mg/80 mg 40 mg/200 mg 80 mg/400 mg 160 mg/800 mg 1 mL 2 mL 5 mL 1/2 double-strength tablet (or 1 singlestrength tablet) 1 double-strength tablet In the event of mild reaction: If the patient experiences a mild reaction or itching, the same dosage should be given for an additional day. If the reaction diminishes, the patient may advance to the next dosage; if the reaction worsens, the TMP-SMX should be discontinued. Antihistamines or antipyretics may be used to treat symptoms of mild reactions. In case of severe reaction: the desensitization regimen should be discontinued. Patient Education For home desensitization regimen Explain the benefits of using TMP-SMX. Be sure the patient understands and is able to follow instructions. • Measure your dose carefully and take it each morning, followed by a glass (6-8 oz) of water. (The patient should do a demonstration, if possible, using the syringe that will be used for the actual measuring at home.) TMP-SMX can make you very ill unless you pay attention to any problems you have. It is extremely important that you check your temperature each afternoon. If your temperature is more than 100.5° F by mouth, stop taking the drug and contact your clinician. Note: If you have shaking chills, check your temperature as soon as the shaking stops, and contact the clinic. If you continue the medication despite a red rash and/or fever, serious illness or a life-threatening reaction may occur. Report any adverse event immediately. Stop the regimen and return to the clinic or emergency room immediately if you develop a red rash, blisters on your skin or in your mouth, or vomiting. Check your skin each evening, and any time you notice itching. • • If you have mild itching or a faint rash, you can take diphenhydramine (Benadryl) 25-50 mg. every 4 hours as needed. If this persists, stay with the same dosage for an additional day; and call or go to the clinic if you have questions or concerns. • Call or go to the clinic for alternate dosage instructions in the event of persistent itching without rash. For all desensitized patients • After desensitization is complete, continue to take the daily dosage. If the drug is stopped, the entire regimen may have to be repeated. Sulfa Desensitization Long Protocol For the first 5 days dilute the standard TMP40/SMX200/5ml suspension and use as follows. Solution preparation: One (1) ml TMP40/SMX200 + 9ml saline in 10ml syringe = 4mg/ml SMX. Dosing Day Day Day Day Day 1, 2, 3, 4, 5, take take take take take 0.25ml = 1mg SMX 0.5ml = 2mg SMX 1ml = 4mg SMX 2ml = 8mg SMX 4ml =16mg SMX Then switch to standard susp and use full strength: Day Day Day Day 6, 7, 8, 9, take take take take 0.5ml = 20mg SMX 1ml = 40mg SMX 2ml = 80mg SMX 4ml =160mg SMX Then switch to tabs as follows: Day 10, take 1 SS tab (adults) or 1/2 SS tab (<12 y/o) If no rash, begin 1 SS tab (adults) or 1/2 SS tab or 5ml standard susp (<12 y/o) BID for 30 days. After 30 days continuous therapy w/o rash, may give full dose. Source: Purdy, Ann Int Med, 1984:100; 512-14 © 2000-2006 Pharmacy OneSource, Inc. การแพ้ยาแบบ type IV Hypersensitivity Reaction หรือ Delayed type Hypersensitivity เป็นปฏิกิริยาที่เกิดจากการเกิด inflammatory reaction โดยผ่าน perivascular lymphocytes และ macrophages 1 แนวทางการรักษาการแพ้ยาแบบ Deleyed type Hypersensitivity อย่างหนึ่งคือ การทำา desensitization หลักการ desensitization เป็นการเพิ่มขนาดยาให้กับผู้ป่วยทีละน้อย จนผู้ป่วยสามารถทนยาได้ แม้ไม่ทราบกลไกที่ เกี่ยวกับระบบคุ้มกันของ Desensitization แต่เชื่อว่าวิธีดังกล่าวทำาให้ mast cells ไม่ตอบสนองต่อแอนติเจน จำาเพาะ การทำา desensitization ควรทำาในโรงพยาบาลที่มีความพร้อมในการช่วยชีวิตผู้ป่วย การให้ยา premedication ด้วย antihistamine หรือ corticosteroid ไม่มีประโยชน์เพราะจะไปบดบัง อาการแพ้ยาจาก IgE2 ในการทำา Rapid desensitization มีความจำาเป็นอย่างยิ่งต่อผู้ป่วยที่มีประวัติการแพ้ยา หรือมีผล positive skin test และไม่มีทางเลือกอื่นในการรักษา จำาเป็นที่ต้องใช้ยาตัวนั้นในการรักษา เช่น การทำา desensitization ของยา penicillin และ foreign serum1 Cotrimoxazole desensitization Cotrimaxazole เป็นยาที่ใช้ในการจัดการผู้ป่วยที่มีภาวะภูมิคุ้มกันบกพร่อง โดยใช้ในการป้องกันการติดเชื้อ Pneumocistis carinii, toxoplasmosis and diarrhea ( Isospora belli ) โดยมี การศึกษาการทำา desensitization ยา Cotrimoxazole ในผู้ป่วยที่มีภาวะภูมิคุ้มกันบกพร่อง ตั้งแต่ปี ค.ศ. 1988 จึงทำาให้มีหลากหลาย protocol ซึ่งขอยกตัวอย่างดังนี้ 1. การทำา desensitization ประมาณ 9 - 13 วัน 3 Days TMP/SMX (mg) Volume or tablet 1 – 3 80/40 1 ml. 3 – 6 16/80 2 ml. 5 – 9 40/200 5 ml. 7 – 12 80/400 ½ double-strenge tablet (or 1 single-strength tablet) 9 – 10 and thereafter 160/800 1 double-strength tablet 2. การทำา desensitization ประมาณ 2 วัน 4 DAY TIME SMZ (mg) TMP (mg) 1 9 AM. 4 0.8 11 AM 8 1.6 1 PM 20 4 5 PM. 40 8 2 9 AM. 80 16 3 PM. 160 32 9 PM. 200 40 3 9 PM. 400 80 Every day 400 80 3. การทำา desensitization ประมาณ 4 ชม. 5 hour Dose of TMP - SMZ 0 0.004 / 0.02 mg. 1 0.04 / 0.2 mg. 2 0.4 / 2 mg. 3 4 / 20 mg. 4 40 / 200 mg. 5 160 / 800 mg. คำาถามที่เกี่ยวข้องกับ desensitization ต่อยา cotrimoxazole ใน web site นี้ คือ คำาถามข้อที่ 1025, 3321, 4337, 5594 เอกสารอ้างอิง 1. http://www.merck.com, accessed 24 พ.ย. 48 2. สมเกียรติ วัฒนศิรชัยกุล. Antimicrobial Therapy. ภาวะติดเชื้อ. เม็ดทรายพริ้นติ้ง. กรุงเทพมหานคร. ิ เล่มที1 ; 892 – ่ 893. 3. http://www.hiv.va.gov, accessed 21 พ.ย. 48 4. Dipiro J, et al. Desensitization. Pharmacotherapy A Pathophysiologic Approach. Fifth edition. 1999; 1594 – 1595 5. Glukstein D , Ruskin J. Rapid Oral Desensitization to Trimaetroprim-Sulfamethoxazole (TMP-SMZ): Use in Prophylaxis for Pneumocystis carinii Pneumonia in Patients with AIDS Who were Previously Intolerant to TMP-SMZ. Clinical Infectious Diseases. 1995; 20: 849 – 853. ระยะเวลาในการสืบค้น : 2 ชัวโมง ่ Keywords : desensitization , cotrimoxazole, AIDS
Copyright © 2024 DOKUMEN.SITE Inc.