lab monitoring

8/6/2019 Lab Monitoring

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Copyright 2010 by Therapeutic Research CenterPharmacists Letter / Prescribers Letter ~ P.O. Box 8190, Stockton, CA 95208 ~ Phone: 209-472-2240 ~ Fax: 209-472-2

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Drug Test Frequency or Indication for Test Rationale CommentsACEI or ARB Potassium

and serumcreatinine

Check potassium and SCr within 1 to 2weeks of initiation (within 1 week in elderly)and after dosage increases, then in 3 to 4weeks if stable. 1,6,8,37 If SCr increased, check again in 2 to 3 weeks, and again in 3 to 4weeks. 6 Then check once or twice yearly, and when patient condition or medicationschange. 6-8 Low-risk patients (see comments) withserum potassium 4.5 mEq/L or less couldwait 3 to 4 weeks before initial assessment. 9 Product labeling generally recommendsmonitoring potassium frequently if co-administered with potassium or potassium-sparing diuretics. Routinely monitor renal function andelectrolytes when used with aliskiren(Tekturna [U.S.], Rasilez [Canada]) inpatients with diabetes. 98

Kidney perfusionin some patients ishighly dependenton angiotensin 6,8

Disco Disco>30% wdespite Risk diabetediureticfemale,60 mL/low albhypo- o No evACEI.

Antiarrhythmics Liverfunctiontests

Amiodarone: Baseline and every sixmonths 30

Hepatotoxic Amiobe asymcontinuto hepa AmioULN, obaselindiscont

Potassiumlevel

Flecainide ( Tambocor ): baseline 35 Potassiumdisturbances mayalter drug effects

Correadmini


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Drug Test Frequency or Indication for Test Rationale CommentsAntiarrhythmicscontinued

Thyroidfunctiontests

Amiodarone: Baseline and every sixmonths 30

Can causehypothyroidismorhyperthyroidism

Incidhigh as Incidhigh as Manadisconthypothyantithyrhyperth

Antiarrhyth-mic level

Flecainide ( Tambocor ):35,38 routine care (checking trough

periodically may be useful) heart failure (goal trough < 0.7 to 1

mcg/mL recommended) liver impairment (early and frequent

monitoring required to guide dose) severe renal impairment (CrCl 35mL/min/1.73m 2 or lower) (frequentmonitoring [daily trough, perCanadian labelling] required to guidedose)

moderate renal impairment (may behelpful during dosage adjustment)

use with amiodarone (stronglyrecommended to guide dose)

use in elderly (daily troughrecommended during dose

adjustment, per Canadian labelling) Mexiletine: in the event of potential druginteractions (phenytoin, rifampin,phenobarbital, cimetidine) 36

Narrowtherapeutic indexdrug

Fleca1 mcg/m Increstate acrenal an Mexi

mcg/mLpost-docentral concern(arrhyth


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Drug Test Frequency or Indication for Test Rationale CommentsAnticonvulsants,continued

Completeblood count

Carbamazepine: baseline, monthly for 2 or3 months, then at least every-other-year 17

Felbamate: baseline, frequently duringtherapy, and for a significant time afterdiscontinuation 28

Can causebone marrowsuppression

Renalfunction

Carbamazepine: baseline and periodicurinalysis and BUN 18

Zonisamide ( Zonegran ): periodically 27

Can cause renaldysfunction

Most anadjustmimpairm

HLA-B*1502genotyping

Carbamazepine: baseline in high-risk patients (i.e., those of Asian ancestry) 18

HLA-B*1502allele associatedwith serious skinreactions

High preThailandPhilippiChina (4

South A4%, but Plateletcount,coagulationtests

Valproate a: check platelet count andcoagulation tests baseline, periodically, priorto planned surgery. 19,20 Monitor clottingparameters in pregnancy. 19,20

Can causethrombocytopenia

Ammonialevel

Valproate a: in event of lethargy, vomiting,mental status change, hypothermia 19,20

Topiramate ( Topamax ): if encephalopathicsymptoms occur 24

Can causehyperammonemia

Concomincrease

Bicarbonate Topiramate ( Topamax ): baseline andperiodically 24 Zonisamide ( Zonegran ): baseline andperiodically 27

Can causemetabolic acidosis


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Drug Test Frequency or Indication for Test Rationale CommentsAntipsychotics,Atypical (cont.)

paliperidone[ Invega ],

quetiapine[Seroquel ],risperidone[ Risperdal ],ziprasidone[Geodon (U.S.),

Zeldox (Canada)])

Lipids Baseline, at 12 weeks, then every two toevery five years if normal. 52,53 Check morefrequently if clinically indicated. Someclinicians check every three months to yearly.

Checking every three months during the firstyear has been suggested. 52

Can increase totalcholesterol, LDL,and triglycerides 52

White bloodcell count,absolute,neutrophilcount

Clozaril (clozapine): See product labelingfor schedule.

Can causeagranulocytosis 55

Some adjustmimpairm Diabe

among a Antipsycsubscrib

Digoxin (e.g., Lanoxin )

Digoxinlevel

Reasons to check digoxin level:

Suspected toxicity 32,33

Confirm level is therapeutic 33

Suspected non-adherence 32

Diseases or physiologic changes (e.g., renalimpairment, thyroid disease) 32,34

Starting or stopping an interacting drug 32,34

Change in dose: check after 5 to 7 days(steady-state) 32


Therape heart f atrial f Check May tain severe


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Drug Test Frequency or Indication for Test Rationale CommentsLithium,continued

Serumlithiumlevel

Twice per week until serum concentrationsand clinical condition have stabilized, then atleast every two months and if symptomatic. 95,97 Check more frequently if used withACEI/ARB or diuretic (avoid concomitant useif possible). 95,100

Monitor closely if used with metronidazoleof fluoxetine. 95

Check when patients initiate or discontinueNSAIDs. 95


Pregnancytest

In women of childbearing potential, atbaseline and if suspected. 97

May beteratogenic duringfirst trimester 97

Renal

function

Serum creatinine, BUN, urinalysis, and urine

specific gravity or osmolality baseline, yearly,and if symptoms arise. 96,97

Renal function can

affect lithiumlevels; lithium canaffect renalfunction 97

Metformin Hemo-globin,hematocrit,red bloodcell indices

Baseline and at least annually 58 Metformin cancause B12deficiency andmegaloblasticanemia

Serum

creatinine

Baseline and at least annually; [Canadian

labelling recommends every six months]58,59

Renal impairment

can causemetforminaccumulation andlactic acidosis

Contraincreatininin men o[Canadicreatininumol/L mL/min


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Drug Test Frequency or Indication for Test Rationale CommentsNiacin ( Niaspan[U.S.], Niaspan

FCT [Canada], Niacor [U.S.])

Liverfunctiontests (AST,ALT)

Baseline, then every six to 12 weeks for ayear, then periodically (e.g., every sixmonths) 60,61

Dose-dependenthepatotoxicity 60

Discontiat 3 timenausea,

Uric acid Baseline, 6 to 8 weeks later, then annually, oras clinically indicated 60

Dose-dependentrisk of hyperuricemia 60

Use withgout. 61,6

Glucose,fasting

Baseline, 6 to 8 weeks later, then annually, oras clinically indicated 60

Dose-dependentimpaired glucosetolerance 60

Patients should hduring thdosage i

Creatinekinase

Periodically [U.S. labeling specifies in theevent of muscle pain, tenderness, orweakness] 61,63

Risk of rhabdo-myolysis 61

Risk facin the elfailure, ohypokal

Potassium Periodically [U.S. labeling specifies in theevent of muscle pain, tenderness, orweakness] 61,63

Risk of rhabdo-myolysis 61

Hypokaand rhab

Phosphorus Periodically in patients at risk of hypophosphatemia 61

Dose-dependentrisk of decrease inphosphorus level 61

Usually

Nonsteroidal anti-inflammatorydrugs (NSAIDs)

Serumcreatinine

Periodically. 65 High-risk patients (seecomments): check weekly for the first severalweeks. 66

Prostaglandininhibition reducesrenal blood flow;other renal injury 65

Discon

consiste High rimpairmACEI/Acomorbidepletio


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Drug Test Frequency or Indication for Test Rationale CommentsNonsteroidal anti-inflammatorydrugs (NSAIDs),continued

Serumcreatinine,continued

Some Ndiclofenketorolanaproxeimpairm Also, m

Pennsaidlabeling

Completeblood count

Periodically 65 Check hemoglobin or hematocrit in thecase of signs or symptoms of anemia. 65

Can cause anemiaand rarely bonemarrowsuppression

NSAIDfluid reterythrop Also m

Pennsaidlabeling

Liver

functiontests (ALT )

Periodically in all patients 65

Check within four to eight weeks of initiation in patients taking diclofenac. 82

Check within eight weeks of initiation inpatients with pre-existing liver disease. 66

Also see our chart , Liver Function Test Scheduling

NSAIDs carry

varying risks of rare hepatotoxicity

Discon

with liveliver tes Severeinclude CanadiNSAIDs Also m

Pennsaidlabeling

Psoriasismedications

Calcium Calcipotriol ( Dovonex , Dovobet ): baselineand regularly [Canada]. 71 Dovobet labellingspecifies monitoring in patients receiving

>100 g weekly [Canada].76

In clinical trials of Taclonex (betamethasone/calcipotriene),calcium was checked at week four of treatment. 72

Vitamin D analog;can increasecalcium levels

If calciuse and Monitocoverag


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Drug Test Frequency or Indication for Test Rationale CommentsPsoriasismedications,continued

Liverfunctiontests (AST,ALT, LDH)

Acitretin ( Soriatane ): baseline, every one totwo weeks until stable, and thereafter asclinically indicated. 73 [Canadian labellingrecommends baseline, every one to two weeksfor two months, then every three months. If abnormal, check weekly.] 74

Hepatotoxic 73 Discontinormalizsevere li

Lipids Acitretin ( Soriatane ): Every one to twoweeks until stable (usually within four to eightweeks). Continue close monitoring in patientswith diabetes, obesity, alcohol use, personalor family history of lipid metabolismdisorder. 73

May increase LDLand triglycerides,and decreaseHDL 73,75

Contrai

Glucose Acitretin ( Soriatane ): Monitor carefully inpatients with diabetes 73

May increase ordecrease bloodglucose 73

Acitretof glibenbeen rep Monitstages o

Retinoids Lipids Isotretinoin: baseline, then until stable(usually by four weeks). Continue frequentmonitoring in patients with diabetes, obesity,alcohol use, personal or family history of lipidmetabolism disorder. 99

Acitretin: See psoriasis medications, above.

May increasetriglycerides andLDL cholesteroland decrease HDLcholesterol 99

LFTs See our chart , Liver Function Test Scheduling and psoriasis medications,above.

Hepatotoxic


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Drug Test Frequency or Indication for Test Rationale CommentsRetinoids,continued

Glucose Isotretinoin: check glucose more frequentlyin patients with diabetes. 99

Acitretin: See psoriasis medications, above

May cause new orworseningdiabetes 99

Educateonset diaincrease

Rheumatoidarthritismedications

Various See our document , Rheumatoid arthritis:the Role of DMARDs and chart, Liver

Function Test Scheduling

Most agents havepotential forserious toxicity

Covers mnonbiolodrugs.

Statins Liverfunctiontests (e.g.,ALT)

See our chart, Characteristics of the VariousStatins

May cause dose-dependent,asymptomatictransaminaseelevations

Creatinekinase

Baseline and when muscle symptoms (e.g.,pain, weakness) occur 77

Can causemyositis andrhabdomyolysis

Risk fasize, higdiabetesinteracti Renal dstatins. Various

Lipids Check lipids six to eight weeks after initiatingor increasing dose. 78

To assess efficacy Assumingoccur w

Thyroidstimulatinghormone

If muscle symptoms occur 77 Hypothyroidismpredisposes tomyopathy 77

Theophylline Theophyl-line level

Check when initiating therapy, before andafter increasing dose, when toxicity suspected(e.g., tachycardia, nervousness, tremor, GIeffects, headache), in the event of new orworsening illness predisposing to toxicity (seecomments), after smoking cessation, after

Narrowtherapeutic indexdrug withinterindividualdifferences inmetabolism

Therap Check hours on Peak foone to twhours po


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Drug Test Frequency or Indication for Test Rationale CommentsTheophylline,continued

Theophyl-line level,continued

adding/stopping an interacting drug (seecomments), and at least annually 80,81

once-da Risk faimpairmseptic sh[39 oC] fhypothyciprofloxor CYP1 Charbrprotein dwort, rifdecrease See ou

Interactiinteracti

ThyroidReplacement

SensitiveTSH

TSH at baseline, every six to eight weeksuntil normal, then every six to 12 months 86,87

TSH six weeks to three months (eight to 12weeks, per labeling) after change in dose orproduct 86,87

Also check if clinically indicated, or if thereis a change in patient health 87

Patients over 50 years of age with cardiacdisease: monitoring interval four to sixweeks 88

Adults


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Drug Test Frequency or Indication for Test Rationale CommentsWarfarin International

NormalizedRatio (INR )

Daily during initiation, until stable in thetherapeutic range, weekly for several weeksonce therapeutic, then every 1 to 4 weeksonce stable 90,91 CHF patients may require more frequentmonitoring due to greater sensitivity 90 Increase frequency after any dose adjustmentuntil stable 90 Increase monitoring after hospital discharge;if interacting drug or natural medicine isadded, discontinued, or taken sporadically; orif brand is changed. 90

Narrowtherapeutic indexdrug withinterindividualdifferences inmetabolism

See our Interacti Drug Intand docuSupplemwarfarinidentifyiinteracti

CYP2C9andVKORC1genotype

Baseline 90 Those with geneticvariations mayneed lower doseand more frequentmonitoring

See our on Clopinforma

a. Valproate refers to products containing divalproex (sodium valproate and valproic acid, e.g., Depakoteacid (e.g., Depakene ).

Users of this document are cautioned to use their own professional judgment and consult any other necessary or appropriate source judgments based on the content of this document. Our editors have researched the information with input from experts, governmorganizations. Information and Internet links in this article were current as of the date of publication.


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(Detail-Document #260704: Page 17 of 19)

More. . .Copyright 2010 by Therapeutic Research Center

Pharmacists Letter / Prescribers Letter ~ P.O. Box 8190, Stockton, CA 95208 ~ Phone: 209-472-2240 ~ Fax: 209-472-2249www.pharmacistsletter.com ~ www.prescribersletter.com

Project Leader in preparation of this Detail- Document: Melanie Cupp, Pharm.D., BCPS

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Cite this Detail-Document as follows: Recommended lab monitoring for common medications. Pharmacists Letter/Prescribers Letter 2010;26(7):260704.

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