brazjinfectdis2019;23(2):130–133
w w w . e l s e v ie r . c o m / l o c a t e / b j i d
The
Brazilian
Journal
of
INFECTIOUS
DISEASES
Brief
communication
Concentrations
of
rifampicin
in
pre-dose
samples
in
patients
with
pulmonary
tuberculosis
Breno
Kristoffer
Beleza
Uchoa,
Carlos
Augusto
Abreu
Albério,
Ana
Carla
Godinho
Pinto,
Stefania
de
Medeiros
Araujo
Lucena,
José
Luiz
Fernandes
Vieira
∗UniversidadeFederaldoPará,FaculdadedeFarmácia,LaboratóriodeToxicologia,Belém,PA,Brazil
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Articlehistory:
Received27January2019 Accepted2May2019 Availableonline22May2019
Keywords: Infectiousdisease Tuberculosis Rifampicin
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Rifampicinisusedinbothphasesoftreatmentfortuberculosis.Inchronicuse,theshort half-lifeandtheself-inductionofmetabolismcandecreasethelevelsofthedrugbelowthe minimalinhibitoryconcentration.Theaimofthestudywastoinvestigatewhetherplasma concentrationsofrifampicinaresustainedabove0.5g/mLinpatientswithtuberculosis using600mg/day.Rifampicinwasmeasuredinplasmabyhigh-performanceliquid chro-matographyandasputumsmearmicroscopywasperformedinalldaysofthestudy.Atotal of44malepatientscompletedthestudy.Ondays31,61and91,themeanplasma concen-trationsofrifampicinwere0.6(0.5)g/mL,0.55(0.5)g/mLand0.46(0.4)g/mL.Therewas ahighvariationofrifampicinlevelsleadingtoahighpercentageofsampleswith concen-trationsbelow0.5g/mL.Therewasnosignificantassociationbetweenthefrequencyof sampleswithdruglevelsbelow0.5g/mLwiththeconversionofthesputummicroscopy. Thesedatasuggestthatpre-dosessamplesofferlimitedinformationontheexposureofM. tuberculosistorifampicin.
©2019PublishedbyElsevierEspa ˜na,S.L.U.onbehalfofSociedadeBrasileirade Infectologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).
Tuberculosisis arelevanthealthissuein Brazilwithabout 70,000newcasesdiagnosedeachyear.Thetreatment com-prises a fixed-dose combination of rifampicin, isoniazid, pyrazinamide,andethambutol(RHZE)intheintensivephase andrifampicinwithisoniazid(RH)inthecontinuationphase. RifampicinisahydrazoneofarifamycinBderivativewith N-amino-N-methylpiperazineapprovedbytheFoodandDrug Administrationfortreatmentofthediseasesince1971.1–3
ThetimeofexposureofM.tuberculosistorifampicin con-centrationsabove the MIC (0.25–0.5g/mLfor wild-type of
∗ Correspondingauthor.
E-mailaddress:jvieira@ufpa.br(J.L.Vieira).
Mycobacterium)isthebestdeterminantofpatientoutcome.4,5
However, there is a high variation in rifampicin plasma concentrations after therapeutic doses, which is related to the patients (age, sex, weight, ethnicity, malabsorption, comorbidity, compliance with prescribed regimen, genetic polymorphism of drug metabolizing enzymes and trans-porters),aswellastothedrugadministered(qualityofthe drugdispensedanddrugformulation).Asaresult,adequate exposureofM.tuberculosistothedrugpromotingdetrimental impactonoutcomecanbeimpaired,suchastreatmentfailure, relapseofinfectionandemergenceofresistance.3,6–8
Chronicuseofrifampicinincreasestherateof disappear-anceofthedrugfrombloodintheearlyphaseofthetreatment
https://doi.org/10.1016/j.bjid.2019.05.001
1413-8670/©2019PublishedbyElsevierEspa ˜na,S.L.U.onbehalfofSociedadeBrasileiradeInfectologia.Thisisanopenaccessarticle undertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
brazj infect dis.2019;23(2):130–133
131
with a consequent reduction of its half-life as well as of drugexposure,whichisrelatedtoitsshorthalf-lifeand self-inductionofmetabolism.3,9Theobjectiveofthecurrentstudy
wastoinvestigatewhethertheconcentrationsofrifampicin inplasmaaresustainedabovetheMICinpre-dosesamples collected inbothphases oftreatment inBrazilianpatients withpulmonarytuberculosisonchronicuseofdailydosesof 600mgofthedrug.
This was a prospective study carried out between Jan-uary2017and July2018incasesofpulmonarytuberculosis receiving care at the Health Unit of Guama District, City ofBelem,PA,Brazil.Theinclusioncriteriawere adultmale patientswithclinical,laboratoryandradiologicaldiagnosisof pulmonarytuberculosis.Exclusion criteriawereuseof anti-tuberculosisdrugsinthelast30days,casesofretreatment, children, and those coinfected with HIV, hepatitis A, B, C orEviruses, drugaddictionincluding ethanolandtobacco, diabetes mellitus,hepatic or renal diseases, or those with ahistoryofallergy toanti-tuberculosisdrugs.Eachpatient receivedadailytotaldose ofrifampicin (600mg),isoniazid (300mg) pyrazinamide(1600mg) and ethambutol (1100mg) for two months (intensive phase), followed by rifampicin (600mg)plusisoniazid(300mg)forfourmonths(continuation phase).10Intheintensivephase,thedrugsweredispensedas
fixed-dosecombinationcontainingrifampicin(150mg), isoni-azid(75mg),pyrazinamide(400mg),andethambutol(275mg). In the continuation phase, the drugs were dispensed as fixed-dosecombination containingrifampicin (300mg) and isoniazid (150mg). Both formulations were from the same batchand were provided and analyzed byFarmanguinhos (Fiocruz,RiodeJaneiro,Brazil).Theclinicalstaffofthe tuber-culosisprogramfromthebasichealthunitwasresponsiblefor prescribinganddispensingthedrugs.Thepatientsandtheir relativesreceivedspecificinstructionsaboutthe administra-tiononeachdayandwerestronglyrecommendedtocomplete thecourseoftreatment.Patientswererequestedtoreturnfor follow-upmonthlyontwooccasions: inthefirst,theywere clinicallyevaluated,receivedthemonthlydosesofthedrugs andtheresearchteamsupervisedtheadministrationofthe firstmonthlydose.Inasecondoccasion,thepatientswere requestedtoreturntothehealthunit24hafterthedirectly observeddoseand beforethenextdoseforbloodsampling andsputumsmearformicroscopyondays31,61and91.
Rifampicin was measured by high-performance liquid chromatographyusingaFlexar®system(PerkinElmer),after liquid–liquid extraction from plasma, following the proce-dureproposedbyZhouetal.(2010)withmodifications.11The
mobile-phasewasacetonitrile:phosphatebufferpH3.0(40:60 v/v) at a flow of 1mL/min and the column was an RP18, 150mm×4.5mm(PerkinElmer)at30◦C.Theeluentwas mon-itoredat254nm.Thelimitofdetectionwas0.01g/mLandthe limitofquantificationwas0.02g/mL.Themethodwaslinear from0.02g/mLto2g/mL.Thewithinandthebetweendays variabilitywere12%and16%andthemeanrecoverywas90%. Qualitative data are presented as frequencies of occur-renceandtheconcentrationsofrifampicininplasmaasmean with95%confidenceinterval.Categoricalvariableswere com-paredbychi-squaredtest.One-wayanalysisofvariancewas usedtocomparetheconcentrationsofrifampicininplasma amongdaysofbloodsampling.DatawereanalyzedusingSPSS
3 2 1 0 31 61 91 Day Rif ampicin ( µ g/mL)
Fig.1–Plasmarifampicinconcentrationsinpatients (n=44)withpulmonarytuberculosisusing600mg/day,24h afterasuperviseddose.Thehorizontallineinlefty-axis correspondstoMICof0.5g/mL. 100 80 60 40 20 0 31 61 91 P ercentage (%) Days
Fig.2–Percentageofpatientswithresidualrifampicin concentrationsbelow0.5g/mL()and0.25g/mL( )in thedaysofbloodsampling.
software,release 21(IBMInc,Chicago,IL,EUA).The signifi-cancelevelwas5%.
ThestudyprotocolwasrevisedandapprovedbytheEthics Committee of the Nucleo de Medicina Tropical da Univer-sidade FederaldoPará(Brazil),undernumber1.591.019.All patientsgavewrittenconsentbeforeinclusioninthestudy.
Forty-fourmalepatientscompletedthestudy.Themean age was 28±12 years (range, 21–45 years), and the mean weight was 68.2±19.7kg (range 60–96kg). Sputum smear microscopywasnegativeinall patientsaftercompletionof theintensivephaseandremainednegativeuntilcompletion of treatment. The mean dose of rifampicin administered was9.37mg/kg/day(range8.4–11.8mg/kg/day).Atadmission, there were no measurable concentrations of rifampicin in allbloodsamples.Inthecourseofthetreatment,themean levelsofrifampicinwere0.6g/mL(95%CI=0.43–0.78g/mL), 0.55g/mL (95%CI=0.34–0.75g/mL) and 0.46g/mL (95%CI=0.32–0.60g/mL) on days 31, 61 (phase 1) and 91 (phase 2), respectively (F=0.8409; p=0.4346) (Fig. 1). There wasa23%decreaseinmeanrifampicinlevelsinthecourse oftreatment.Next,rifampicinlevelswereallocatedasbelow orabovetheMIC.Ondays31,61and91,52.2%(n=23),54.5% (n=24),and59%(n=26)ofpatientsshowedplasmalevelsof rifampicinbelow0.5g/mL(X2=0.192;p=0.9086),respectively
(Fig.2).Ofthose,38%(n=17),44%(n=19),and42%(n=18)had concentrations of rifampicin below 0.25g/mL (X2=0.111;
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braz j infect dis.2019;23(2):130–133sputumsmearsonday31was70%(n=31),and 55%(n=17) had rifampicin plasma levels below 0.5g/mL (X2=0.129;
p=0.7194). On day 61, all patients showed conversion of sputumsmears.
Time of exposure is more effective than the amount of absorbed drug to assess efficacy of rifampicin.3,8,12 In
70s, the ratio of pre-dose concentration to MIC was the mostrelevantpharmacodynamicindextoassessrifampicin exposure.12 Thereafter, numerous ways to estimate
expo-sure of M. tuberculosis to the drug were reported, such as the measurement of plasma concentration at 2h (Cmax) and6hafterdrugadministrationortheratioof0–24harea undertheconcentration-timecurve(AUC) tothe minimum inhibitoryconcentration(AUC/MIC).3,8,13–15However,thereare
limitationswithbothprocedures,ascollectionofserialblood samplesisalaboriousandexpensiveprocess,andisgenerally notfeasibleinclinicalpractice.
Inthestudy,thepre-dosesampleswerechosentoassess drugexposurebasedonthe followingassertions:(a) thera-peuticdosesshould ensureeffectiveplasma levelsfor24h afterrifampicinintake;and(b)thedrugisactivewhenblood concentrationsareabovetheMIC.12,15Furthermore,the
sam-plingschedulewasbasedonreportsshowingtheabilityof rifampicintoinduceCYPisoformsismostevidentintheearly phaseofthetreatment.3,6,7,12
All plasma samples collected on D0 were negative for rifampicin,confirmingthatthe drughadnotbeen recently usedbythepatientsenrolledinthestudy.Themeanlevelsof rifampicinwereabovetheMICondays31and61,butahigh percentageofsamplespresenteddruglevelsbelow0.5g/mL. Thisfindingcanbeduetoboththeshorthalf-lifeofthedrug aswell astothe normalvariationofthe residuallevels of rifampicin.3,6,7,12
Theconcentrations of rifampicin were similar through-outthestudy,withanon-significantdecreaseof23%inthe courseofthetreatment,whichcouldbeduetothecapacity ofrifampicintoinduceseveralCYPisoformsandtransporters asMDR1andMDR2.Suchinductionbringsdrug concentra-tion to belowthe MIC and increases the range ofresidual levelsofthedrug.3,16,17 Furthermore,severalfactorsrelated
tothepatients,tothedrug,andtothepolicyofdiagnosisand treatmentofthediseasealsoinfluencetheconcentrationsof rifampicin.3,6,7,13,14 Therefore,rifampicin levelsinpre-doses
samplesofferlimitedinformationontheexposureofM. tuber-culosis.
Thefrequencyofsampleswithdruglevelsbelow0.5g/mL wasnotassociatedwithconversionofsputummicroscopy, whichcorroboratesthelimitedinformationofdrugexposure inpre-dosessamplesaswellasthedifficultytointerpret clini-calandbacteriologicaloutcomesofasingledruginafour-drug regimen.Furthermore,variablesofM.tuberculosis,asthe var-iousgrowth ratesinvivo,makeitdifficulttocorrelatedrug efficacywithtimeofconcentrationabovetheMIC.3,5,8,12
Inconclusion,thelevelsofrifampicinwerebelowtheMIC inmostofthesamplesinbothphasesoftreatment,andthere was no significant association between frequency of sam-pleswithdruglevelsbelow0.5g/mLwithconversionofthe sputumsmears.Thesedatasuggestthatpre-dosessamples
offerlimitedinformationontheexposureofM.tuberculosisto rifampicin.
Funding
Thereisnofundingsourcetodeclare.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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