Diclofenac, paracetamol, and vidarabine removal during plasma exchange in polyarteritis nodosa patients

Drug Dosing in Patients Undergoing Therapeutic Plasma Exchange

Therapeutic plasma exchange (TPE) is an extracorporeal process in which a large volume of whole blood is taken from the patient's vein. Plasma is then separated from the other cellular components of the blood and discarded while the remaining blood components may then be returned to the patient. Replacement fluids such as albumin or fresh-frozen plasma may or may not be used. TPE has been used clinically for the removal of pathologic targets in the plasma in a variety of conditions, such as pathogenic antibodies in autoimmune disorders. TPE is becoming more common in the neurointensive care space as autoimmunity has been shown to play an etiological role in many acute neurological disorders. It is important to note that not only does TPE removes pathologic elements from the plasma, but may also remove drugs, which may be an intended or unintended consequence. The objective of the current review is to provide an up-to-date summary of the available evidence pertaining to drug removal via TPE and provide relevant clinical suggestions where applicable. This review also aims to provide an easy-to-follow clinical tool in order to determine the possibility of a drug removal via TPE given the procedure-specific and pharmacokinetic drug properties.

Is Antimicrobial Treatment Effective During Therapeutic Plasma Exchange? Investigating the Role of Possible Interactions

Antimicrobial treatment during therapeutic plasma exchange (TPE) remains a complex issue. Recommendations based on a limited number of experimental studies should be implemented in clinical practice with caution. Effective management of infections due to plasma or albumin-related interactions, as well as impaired pharmacokinetics, in critical illness is difficult. Knowing the pharmacokinetics of the drugs concerned and the procedural aspects of plasmapheresis should be helpful in planning personalized treatment. In general, possessing a low distribution volume, a high protein-binding affinity, a low endogenous clearance rate, and long distribution and elimination half-lives make a drug more prone to elimination during TPE. A high frequency and longer duration of the procedure may also contribute to altering a drug's concentration. The safest choice would be to start and finish TPE before antimicrobial agent infusion. If this not feasible, a reasonable alternative is to avoid administering the drug just before TPE and to delay the procedure for the time of the administered drug's distributive phase. Ultimately, if plasma exchange must be performed urgently or the drug has a very narrow therapeutic index, monitoring its plasma concentration is advised.

Therapeutic Plasma Exchange and Its Impact on Drug Levels: An ACLPS Critical Review

OBJECTIVES

To examine and summarize the current literature on the effects of therapeutic plasma exchange on medication levels.

METHODS

Literature review was performed via searches of the Cochrane Database and PubMed-MEDLINE (1996 to August 2016) looking for all case reports, case series, and human randomized controlled trials involving therapeutic plasma exchange (TPE)-associated drug removal.

RESULTS

Approximately 60 peer-reviewed articles were identified with the majority being case reports; no randomized controlled trials were identified. These reports and the authors' own experiences were used to derive practical guidance regarding the effect of TPE on circulating drug levels.

CONCLUSIONS

There were several limitations with existing studies, many of which relate to procedural and/or clinical properties of patients undergoing TPE. As such, additional studies are needed before definitive guidelines can be established. There is clear need for development of consensus and additional investigations in this domain.

Medications in patients treated with therapeutic plasma exchange: prescription dosage, timing, and drug overdose

Therapeutic plasma exchange (TPE) is an extracorporeal process commonly used in clinical medicine for the treatment of a variety of neurological, renal, hematological, dermatological, and other diseases. Inherent to the procedure, patients' plasma removal may lead to the extraction of drugs they are concurrently receiving. This review discusses the published literature assessing TPE's influence on different drug classes' disposition and, when applicable, sets forth management recommendations in cases where the drugs are used at the usual doses and in cases of drug overdose.

Drug removal by plasmapheresis: an evidence-based review

Contrary to the literature about drug removal during hemodialysis, data regarding drug removal during plasmapheresis are sparse. Over the last 40 years, approximately 70 publications-mostly case reports of overdoses-have described the effects of plasmapheresis on pharmaceutical agents. Important issues are drug extraction during plasma exchange with chemotherapy, as well as drug classes such as antiinfectives, anticoagulants, antiepileptics, cardiovascular agents, and immunosuppressants. Other considerations are the merits and pitfalls of the different methods used in published reports and recommendations for future pharmacokinetic studies in this field.

Pharmacokinetics of teicoplanin during plasma exchange

OBJECTIVE: To study the elimination of teicoplanin during plasma exchange, a procedure currently used to treat a variety of disorders involving immune complexes. Teicoplanin is a glycopeptide antibiotic that exhibits a long terminal half-life (100-150 h) and is highly bound to plasma proteins (unbound fraction (fu)=0.2). METHODS: Twelve adults with systemic polyarteritis nodosa, cryoglobulinemia-induced vasculitis or dysglobulinemic neuropathy undergoing plasma exchange were studied. Each patient received intravenous teicoplanin, 6 mg/kg body weight, immediately before plasma exchange. Plasma was assayed for teicoplanin by high pressure liquid chromatography. RESULTS: A high level of protein binding of teicoplanin was measured within this patient population (98%). The mean quantity of teicoplanin eliminated (+/-SD) was 74.6+/-34.6 mg. The mean drug fraction eliminated by plasma exchange (+/-SD) was 19.5+/-5.6%. Mean fu value as determined by ultrafiltration (+/-SD) was 2.2+/-1.7%. CONCLUSIONS: These results show that plasma exchange influences teicoplanin pharmacokinetics, with a clinically significant quantity being eliminated. If trough teicoplanin concentrations of around 10 mg/L are desired, it is recommended that teicoplanin dosage be supplemented or given after plasma exchange.

Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid class. When given orally the absorption of diclofenac is rapid and complete. Diclofenac binds extensively to plasma albumin. The area under the plasma concentration-time curve (AUC) of diclofenac is proportional to the dose for oral doses between 25 to 150 mg. Substantial concentrations of drug are attained in synovial fluid, which is the proposed site of action for NSAIDs. Concentration-effect relationships have been established for total bound, unbound and synovial fluid diclofenac concentrations. Diclofenac is eliminated following biotransformation to glucoroconjugated and sulphate metabolites which are excreted in urine, very little drug is eliminated unchanged. The excretion of conjugates may be related to renal function. Conjugate accumulation occurs in end-stage renal disease; however, no accumulation is apparent upon comparison of young and elderly individuals. Dosage adjustments for the elderly, children or for patients with various disease states (such as hepatic disease or rheumatoid arthritis) may not be required. Significant drug interactions have been demonstrated for aspirin (acetylsalicylic acid), lithium, digoxin, methotrexate, cyclosporin, cholestyramine and colestipol.

Treatment of polyarteritis nodosa and Churg-Strauss syndrome: indications of plasma exchanges

To define the most effective treatment for polyarteritis nodosa (PAN) and Churg-Strauss syndrome (CSS), we undertook 4 consecutive prospective therapeutic trials including 236 patients and tried to answer several important questions: Should cyclophosphamide (CYC) be given as the first-line treatment? What is the place of plasma exchanges (PE) in the treatment of systemic vasculitis? and does hepatitis B virus (HBV) related PAN require treatment? Our first randomized trial in 71 patients (1981-1983) compared the association of CYC with corticosteroids (CS) and PE to CS and PE, in order to evaluate the efficacy of CYC given as the first-line treatment to control disease activity and subsequent survival of PAN and CSS patients. Between December 1983 and December 1988, we conducted two trials simultaneously: one aimed at patients without HBV markers and the second at patients with HBV markers. In 78 patients without HBV markers, we compared prednisone and PE to prednisone alone as the initial therapeutic regimen. In 33 patients with PAN related to HBV, a new therapeutic strategy was applied as an alternative to long-term steroid and immunosuppressive therapy: short-term steroid therapy and PE were used to control the evolution of PAN and anti-viral therapy was administered to suppress the etiological agent of the vasculitis. In the last protocol including 56 patients and addressed to severe PAN without HBV markers or CSS we have shown that PE did not improve the prognosis and control of the disease. Twelve years after the beginning of the trials on PAN and CSS patients, we think that the therapeutic strategy should be as follows: In PAN without HBV and CSS: prednisone in association with CYC improves the control of the disease despite infectious side effects which may be reduced by better CYC dose adaptation. In PAN related to HBV: The first-line treatment should be the association of anti-viral agents and PE. This treatment was effective and cured a majority of patients within 2 to 3 months; half of them seroconverted. The length of HBV infection before its diagnosis, delay before initiation of treatment and previous immunosuppressive therapy led to a poor seroconversion rate. The role of PE in the treatment of systemic necrotizing vasculitis: PE are obviously useful in PAN related to HBV where immune complex deposition has been demonstrated. When PAN is not related to HBV and in CSS, even in severe cases, there is presently no argument supporting systematic administration of PE at the time of diagnosis.

Pharmacokinetics of cyclophosphamide in patients with systemic necrotizing angiitis

Cyclophosphamide pharmacokinetics were investigated following administration to patients with systemic necrotizing angiitis. Ten patients (eight women and two men) received cyclophosphamide as a 1-h-rate-constant intravenous infusion at doses ranging from 600 to 1200 mg. All patients received concomitant oral prednisone (1 mg/kg/d). Blood samples were collected at the end of drug infusion and 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24 h later. Serum cyclophosphamide concentrations were assayed by high pressure liquid chromatography. The peak serum cyclophosphamide levels ranged from 15.7 to 29.4 mg/L. The mean cyclophosphamide elimination half-life was 6.2 +/- 1.3 h (mean +/- SD). The mean apparent volume of distribution and mean total plasma clearance were, respectively, 0.75 +/- 0.22 L/kg (mean +/- SD) and 83 +/- 22 mL/min (mean +/- SD). These results obtained in systemic vasculitic diseases were consistent with those observed in other studies with cancer patients receiving comparable doses of cyclophosphamide.

Pharmacokinetics of ceftriaxone during plasma exchange in polyarteritis nodosa patients

Plasma exchange (PE) is currently being used to treat a variety of disorders involving immune complexes, such as polyarteritis nodosa. This procedure removes endogenous toxic components that accumulate in patients with this disease, but it also removes drugs. Plasma-protein binding and the volume of distribution (V) are two kinetic parameters which strongly affect the efficiency of drug removal by PE. Drugs that are highly bound to plasma proteins and have a low V may show a marked decrease in plasma levels as a result of PE. Because ceftriaxone exhibits saturable plasma-protein binding, which influences its pharmacokinetic parameters, particularly its V, we evaluated its removal during PE therapy in this nonrandomized crossover study. Twelve polyarteritis nodosa patients undergoing PE were studied. Each patient was given ceftriaxone intravenously in doses of 1 and 3 g on days 4 and 11, respectively, immediately before (n = six patients; group I) and 6 h before (n = six patients; group II) PE. Plasma was assayed for ceftriaxone by high-pressure liquid chromatography. The mean amounts eliminated +/- standard deviations were 230.8 +/- 38.5 mg (1 g) and 750.0 +/- 168.5 mg (3 g) for group I and 161.0 +/- 66.0 mg (1 g) and 347.0 +/- 121.0 mg (3 g) for group II. The drug fractions eliminated by PE were 23.0% +/- 3.9% (1-g dose) and 24.9% +/- 5.6% (3-g dose) for group I (P > 0.05), and 16.6% +/- 5.9% (1-g dose) and 11.5% +/- 4.0% (3-g dose) for group II (P < 0.05). These results showed that the drug fraction eliminated decreased when V increased only when the distribution phase of ceftriaxone had been completed (group II). These findings suggest that PE may influence ceftriaxone disposition and that it would be better to administer the drug after PE to assure its therapeutic efficacy.

Zidovudine removal during plasma exchange

Pharmacokinetics of zidovudine (azidothymidine, AZT) were investigated after oral administration (300 mg every 8 hours) in a human immunodeficiency virus seropositive patient who was also treated with plasma exchange (60 ml/kg). Plasma AZT concentrations were measured using high performance liquid chromatography assay. Plasma exchange clearances reached 1-3.8% of the total clearance. The fraction of AZT removed from separated plasma accounted for only 1% of the administered dose. The contribution of plasma exchange to the elimination of AZT appears to be negligible. Solely on the basis of AZT pharmacokinetic data, no particular dose adjustment appears to be necessary in patients treated with multiple plasma exchanges.