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PHARMACOKINETICS IN PATIENTS REQUIRING RENAL REPLACEMENT Rx Arthur J. Atkinson, Jr., M.D. Senior Advisor in Clinical Pharmacology Clinical Center, NIH.

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Presentation on theme: "PHARMACOKINETICS IN PATIENTS REQUIRING RENAL REPLACEMENT Rx Arthur J. Atkinson, Jr., M.D. Senior Advisor in Clinical Pharmacology Clinical Center, NIH."— Presentation transcript:

1 PHARMACOKINETICS IN PATIENTS REQUIRING RENAL REPLACEMENT Rx Arthur J. Atkinson, Jr., M.D. Senior Advisor in Clinical Pharmacology Clinical Center, NIH Gregory M. Susla, Pharm. D. Clinical Science Specialist The Bayer Corporation

2 FIRST DESCRIPTION OF HEMODIALYSIS IN ANIMALS* * From: Abel JJ, et al. J Pharmacol Exp Ther 1914;5:

3 ELIMINATION BY DIFFERENT ROUTES MEASUREMENTS RENAL HEPATIC DIALYSIS BLOOD FLOW +* +* + AFFERENT CONC EFFERENT CONC ELIMINATED DRUG *not actually measured in routine PK studies

4 GOALS OF DIALYSIS DISCUSSION DISCUSSION OF DIALYSIS CLEARANCE MECHANISTIC - RENKIN APPROACH EMPIRICAL FICK EQUATION RECOVERY CLEARANCE EFFECTS OF DIALYSIS ON PHARMACOKINETICS HEMODYNAMIC CHANGES DURING DIALYSIS USE OF KINETIC METHODS FOR ANALYSIS PATHOPHYSIOLOGIC CONSEQUENCES

5 IMPACT OF CL D

6 RENKIN DIALYSIS EQUATION* * From Renkin EM. Tr Am Soc Artific Organs 1956;2:102-5

7 EFFECT OF MOLECULAR WEIGHT (M) ON SOLUTE DIFFUSIVITY (D)* * From Henderson LW: In: Brenner BM, Rector FC Jr. The kidney. 1976, p INULIN

8 DIALYZER PERMEABILITY VS. FREE WATER DIFFUSION COEFFICIENTS * From Gibson TP et al. Clin Pharmacol Ther 1976;20: RATIO OF DIALYZER PERMEABILITY COEFFICIENTS*1.29  0.22 RATIO OF FREE WATER DIFFUSION COEFFICIENTS1.23

9 DIALYSIS CLEARANCE VS. DIALYZER BLOOD FLOW* * From Renkin EM. Tr Am Soc Artific Organs 1956;2:102-5

10 FICK EQUATION Q = DIALYZER BLOOD FLOW A = CONCENTRATION IN BLOOD COMING TO DIALYZER V = CONCENTRATION IN BLOOD LEAVING DIALYZER E = EXTRACTION RATIO

11 FICK EQUATION

12 CALCULATION OF RECOVERY CLEARANCE U = DIALYSATE CONCENTRATION V = DIALYSATE VOLUME t = DIALYSIS TIME P = MEAN PLASMA CONCENTRATION

13 PLASMA VS. BLOOD CLEARANCE

14 GOALS OF DIALYSIS DISCUSSION DISCUSSION OF DIALYSIS CLEARANCE MECHANISTIC - RENKIN APPROACH EMPIRICAL FICK EQUATION RECOVERY CLEARANCE EFFECTS OF DIALYSIS ON PHARMACOKINETICS HEMODYNAMIC CHANGES DURING DIALYSIS USE OF KINETIC METHODS FOR ANALYSIS PATHOPHYSIOLOGIC CONSEQUENCES

15 DATA SOURCES FOR PK ANALYSIS

16 KINETIC MODEL USED TO ANALYZE HEMODIALYSIS DATA* * From Stec GP, et al. Clin Pharmacol Ther 1979;26:

17 KINETIC MODEL USED TO ANALYZE HEMODIALYSIS DATA* * From Stec GP, et al. Clin Pharmacol Ther 1979;26:

18 FICK CLEARANCE EQUATION

19 NAPA IN RBC IS DIALYZED * Q EFF = [ (1 - Hct) + (RBC/P) (HCT) ] Q MEAS

20 TWO PROBLEMS WITH FIXED- PARAMETER MODEL* * From Stec GP, et al. Clin Pharmacol Ther 1979;26: DURING DIALYSIS [A] AND [V] DROP MORE THAN EXPECTED FROM DRUG RECOVERY 2. AFTER DIALYSIS CONCENTRATION REBOUND IS LESS THAN EXPECTED

21 KINETIC MODEL USED TO ANALYZE HEMODIALYSIS DATA* * From Stec GP, et al. Clin Pharmacol Ther 1979;26: Cl S G

22 REDUCTION IN CL S DURING AND AFTER HEMODIALYSIS* * From Stec GP, et al. Clin Pharmacol Ther 1979;26:

23 GOALS OF DIALYSIS DISCUSSION DISCUSSION OF DIALYSIS CLEARANCE MECHANISTIC - RENKIN APPROACH EMPIRICAL FICK EQUATION RECOVERY CLEARANCE EFFECTS OF DIALYSIS ON PHARMACOKINETICS HEMODYNAMIC CHANGES DURING DIALYSIS USE OF KINETIC METHODS FOR ANALYSIS PATHOPHYSIOLOGIC CONSEQUENCES

24 MULTICOMPARTMENTAL MODEL OF INULIN AND UREA KINETICS* * From Atkinson AJ Jr, et al. Trends Pharmacol Sci 1991;12:

25 UREA (  ) AND INULIN (  ) KINETICS DURING AND AFTER HEMODIALYSIS* * From Bowsher DJ, et al. J Lab Clin Med 1985;105: INULIN UREA INULIN

26 RENKIN EQUATION* * From Renkin EM. Am J Physiol 1953;183: Q = capillary blood flow P = capillary permeability coefficient-surface area product (sometimes denoted PS).

27 RELATIONSHIP BETWEEN BLOOD FLOW (Q) AND CL I * * From Bowsher DJ, et al. J Lab Clin Med 1985;105:

28 UREA AND INULIN KINETICS DURING AND AFTER HEMODIALYSIS * ESTIMATED AS C.O. - Q S

29 RENIN-ANGIOTENSIN SYSTEM ACTIVATION DURING AND AFTER HEMODIALYSIS* * From Bowsher DJ, et al. J Lab Clin Med 1985;105:

30 DIFFERENT MICROCIRCULATORY ACTIONS OF ANGIOTENSIN II AND AVP* * From Atkinson AJ Jr: The Pharmacologist 1989;31:

31 EFFECT OF AVP ON P  S* * From Atkinson AJ Jr: The Pharmacologist 1989;31:

32 CLINICAL CONSEQUENCES OF DIALYSIS- ASSOCIATED HEMODYNAMIC CHANGES PATHOGENEIC ROLE IN DIALYSIS- ASSOCIATED SKELETAL MUSCLE CRAMPS IMPACT ON HEMODIALYSIS THERAPY OF DRUG TOXICITY

33 PATHOGENESIS OF DIALYSIS-ASSOCIATED SKELETAL MUSCLE CRAMPS HEMODIALYSIS PLASMA VOLUME CONTRACTION UNMODULATED SYMPATHETIC ACTIVATION PERIPHERAL VASOCONSTRICTION DERECRUITMENT OF MUSCLE CAPILLARIES IMPAIRED MUSCLE OXYGENATION SKELETAL MUSCLE CRAMPS X  NaCl, MANNITOL X  PRAZOSIN ACE INHIBITOR  +

34 ACTIONS OF ANGIOTENSIN II & SYMPATHETIC NERVOUS SYSTEM SYMPATHETIC NERVOUS SYSTEM SYMPATHETIC NERVES

35 ONLY SOME PATIENTS HAVE DIALYSIS- ASSOCIATED SKELETAL MUSCLE CRAMPS* * Sidhom OA, et al. Clin Pharmacol Ther 1994;56:445-51

36 CLINICAL CONSEQUENCES OF DIALYSIS- ASSOCIATED HEMODYNAMIC CHANGES PATHOGENEIC ROLE IN DIALYSIS- ASSOCIATED SKELETAL MUSCLE CRAMPS IMPACT ON HEMODIALYSIS THERAPY OF DRUG TOXICITY

37 DIALYSIS CASE HISTORY A 67 year-old woman became lethargic and confused and developed hypotension, renal insufficiency, junctional tachycardia and intraventricular conduction delay after ingesting an estimated 7gm of procainamide (PA). Plasma PA and NAPA concentrations were 57 μg/mL and 55 μg/mL, respectively.

38 DIALYSIS CASE HISTORY (cont.) Hemodialysis was performed for 4 hr. By the end of the second hour BP was maintained in the range of 110/80 mm Hg without vasopressor therapy. At the end of dialysis, the patient was alert and oriented although only 340 mg of PA and 470 mg of NAPA had been removed by this procedure.

39 DIALYSIS CASE HISTORY (cont.) Fifteen hours after dialysis, PA and NAPA levels were 9.2 μg/mL and 33 μg/mL, respectively. The patient had returned to normal sinus rhythm with QRS = 0.12 sec.

40 KINETIC ANALYSIS OF HEMODIALYSIS FOR PROCAINAMIDE TOXICITY* * From: Atkinson AJ Jr, et al. Clin Pharmacol Ther 1976;20:

41 KINETIC ANALYSIS OF HEMODIALYSIS FOR PROCAINAMIDE TOXICITY* 50.4 L GUT 60.4 L 340 mg470 mg DIALYSIS * From: Atkinson AJ Jr, et al. Clin Pharmacol Ther 1976;20: PANAPA Clearances in mL/min

42 WAS DIALYSIS EFFICACIOUS? DIALYSIS INCREASED DRUG CLEARANCE PA – TWO FOLD NAPA – 3.8 FOLD BUT 4 hr OF DIALYSIS REMOVED ONLY 340 mg PA 470 mg NAPA HOWEVER, BLOOD LEVELS FELL SUBSTANTIALLY PA: 25.7 µg/mL 15.5 µg/mL NAPA: 47.0 µg/mL35.5 µg/mL AND PATIENT’S CONDITION STABILIZED

43 PA & NAPA KINETICS IN TOXIC PATIENT NORMALPATIENT PANAPAPANAPA t 1/2 (hr) V dβ (L/kg) CL E (mL/min) CL D (mL/min)

44 ESTIMATION OF V d Question: Why did the patient appear to respond to hemodialysis when so little PA and NAPA were removed by this procedure?

45 SEQUESTRATION OF DRUG IN SOMATIC TISSUES 83L CL F 14L CL S 7L CL E BIOPHASE CL D DIALYSIS

46 EFFICACY OF EXTRACORPOREAL TREATMENT OF DRUG TOXICITY EFFICIENCY OF DRUG REMOVAL SOMETIMES SUFFICES TO AMELIORATE DRUG TOXICITY. ↓ INTERCOMPARTMENTAL CLEARANCE FROM SOMATIC TISSUES CAN CONTRIBUTE TO BENEFICIAL CLINICAL RESPONSE > EXTENT OF DRUG REMOVAL.


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