CH3

CH

`CH3

NH

Volume 55, Number IPrinted in the U.S.A.

INTERNATIONAL JOURNAL OF LEPROSY

Pharmacokinetics of Clofazimine inHealthy Volunteers'

Zuzana Schaad-Lanyi, Walter Dieterle, Jean-Pierre Dubois,Walter Theobald, and Wolfgang Vischer2

Clofazimine, 3-(p-chloroanilino)-10-(p-chloropheny1)-2,10-di-hydro-2-(isopropyl-imino)phenazine (Fig. 1), is active againstMycobacterium leprae in experimental an-imals and in man (4, ". 12). In the form ofLamprene ®, it is in use for the treatment ofleprosy (2-5' 10' 13). Although clofazimine wasintroduced into leprosy treatment in the1960s, only a few studies on its disposition,either in humans or in animals, have beenreported (1. 8' 9' 14). Information on the phar-macokinetics of clofazimine in man is stilllacking.

The present paper describes the results ofinvestigations on the pharmacokinetics ofclofazimine after single and multiple oraladministration to healthy volunteers.

SUBJECTS AND METHODSSubjects. Twelve healthy male volunteers

between 30 and 60 years of age (mean = 42years) and weighing 64-92 kg (mean = 74kg) participated in this study, and gave theirinformed consent after the properties of thedrug and the aims of the study had beenexplained to them. They remained undermedical supervision throughout the study.The volunteers were asked to take no med-ication for at least 2 weeks before the study,and no other drugs except clofazimine dur-ing the study.

Dosing and collection of samples. Thestudy was carried out in three experiments.In the first experiment, three subjects re-ceived single oral doses of 200 mg of clo-fazimine (four capsules of Lamprene ®, each

' Received for publication on 7 July 1986; acceptedfor publication on 4 September 1986.

= Z. Schaad-Lanyi, Dr.phil.II; W. Dieterle, Dr.rer.nat.;W. Vischer, Dr.med., Pharma Research and Devel-opment, R-1005.6.23, CIBA-GEIGY Limited, CH-4002Basle, Switzerland. J.-P. Dubois, Dr.phil.II, Biophar-maceutical Research Center, Laboratoires CIBA-GEI-GY SA, Rueil Malmaison, France. W. Theobald,Dr.med., Medical Experimental Pharmacokinetics,CIBA-GEIGY Limited, Basle, Switzerland.

containing 50 mg of clofazimine) on twooccasions in random sequence separated by4 weeks. On one of these occasions, clofazi-mine was administered on an empty stom-ach after an overnight fast. The subjectscontinued to fast for another 2 hr. Then astandardized breakfast, consisting of tworolls with jam and decaffeinated black cof-fee, was served to them. On the other oc-casion, clofazimine was administered 10min after a breakfast containing fat andproteins (two rolls with butter and jam, cof-fee with milk).

In the second experiment, a single oraldose of 200 mg of clofazimine was given tosix subjects 10 min after a breakfast con-taining fat and proteins.

In the third, multiple-dose experiment,three subjects received 50-mg oral doses ofclofazimine in the morning 10 min afterbreakfast for 8 consecutive days.

Blood samples were withdrawn into hep-arinized venojects before and 1, 2, 4, 8, 12,24, 48, 96, 168, (192), 216, (240), and 264

C l

FIG. I. Clofazimine, molecular weight = 473.4.

9

1500

)

1 000a.

o 5000

10^ International Journal of Leprosy^ 1987

hr after administration of the single dose.During repeated administration, bloodsamples were withdrawn immediately be-fore administration of the daily dose on days1, 3, 5, and 8, as well as 1, 2, 4, 8, 12, 24,48, 96, 168, 216, and 264 hr after the lastdose (day 8). The blood samples were cen-trifuged as soon as possible, and the plasmasamples were stored at —20°C until ana-lyzed.

Analysis. The concentrations of clofazi-mine in plasma were measured by the thin-layer chromatographic method publishedpreviously (7), using a sample volume of 1ml for analysis. The method was validatedon a daily basis by analyzing plasma sam-ples spiked with clofazimine.

Pharmacokinetic analysis. The area un-der the plasma concentration-time curve(AUC) was calculated by the trapezoidalrule. The elimination half-life of clofazi-mine was determined from the log-linearplot of the terminal phase of the concentra-tion-time curve.

To predict the plasma concentrations fol-lowing multiple dosing, the mean experi-

mental plasma concentration-time curve ofclofazimine C(t) was fitted by a sum of threeexponential terms,

C(t) = Ae1t + A,e-x2t + A7e-A3tin which A1, A„ and X, are the slopes andA,, A„ and A, are the zero-time interceptsof the three segments, into which the log-linear plot of the concentration-time curvewas resolved.

RESULTSSingle-dose experiments. The plasma

concentration-time curves of clofazimineobtained in six volunteers after administra-tion of a single oral dose of 200 mg of clo-fazimine 10 min after breakfast are shownin Figure 2. The corresponding areas underthe concentration-time curve in plasma(AUC, 0-264 hr), the maximum concentra-tions (Cmax), the times to peak (Tmax), andthe elimination half-lives (t50) are listed inTable 1.

Maximum concentrations of clofaziminein plasma of the six subjects were observedbetween 4 and 8 hr after dosing. The re-

0^48^96^144^192^240

Time [hours]FIG. 2. Plasma concentrations of clofazimine in six healthy volunteers following single oral doses of 200 mg

(4 x 50 mg) of clofazimine with breakfast.

288

800 -

600 -Ea

400 -

200 -

0

55, 1^Schaad-Lanyi, et al.: Pharmacokinetics of Clofazimine^11

24^48^96^144^192^240^288Time after administration [h i

FIG. 3. Mean plasma concentrations of clofazimine after a single 200-mg dose (4 x 50 mg) in healthyvolunteers. (HI) = fasted volunteers (N = 3); (0-111) = 10 min after breakfast (N = 3).

spective concentrations ranged from 567 to1372 pmol/g, with a mean ± S.D. of 861 ±289 pmol/g. The mean AUC value ± S.D.was 33.9 ± 8.4 nmol.h/g.

Table 2 summarizes the AUC values (0—264 hr), the Cmax values, and the peak timesdetermined in the three subjects dosed with200 mg of clofazimine in the fasting stateor immediately after a breakfast. Themean ± S.D. plasma concentration-timecurves with and without breakfast are shownin Figure 3.

Figure 4 illustrates an individual plasmaconcentration profile of one of the subjectsdosed after breakfast in a linear (A) andsemi-logarithmic (B) plot. After both modesof administration, Cmax of clofazimine wasreached within 8-12 hr. Its mean values(±S.D., N = 3) were 604 ± 175 and 469 ±102 pmol/g with and without food, respec-tively. Correspondingly, the mean AUCvalues were different, i.e., 29.1 ± 8.7 nmol.hr/g with breakfast and 18.0 ± 4.5 nmol.hr/g without breakfast.

TABLE 1. Descriptive pharmacokinetic parameters obtained after administration of asingle oral dose Of 200 mg (4 X 50 mg) of clqfazitnine with breakfast in six healthyvolt iii

Subject no. AUC (0-264 hr)(nmol-hr/g)

Cmax(pmol/g)

Tmax(hr)

t,„(days)

1 34.1 968 4 11.830.7 792 8 9.5

3 37.6 832 8 13.84 26.0 567 4 16.05 48.6 1372 86 26.6 633 8 6.4

Mean ± S.D. 33.9 ± 8.4 861 ± 289 8' 10.6 ± 4.0

" Median.

0

1")^ International Journal of Leprosy^ 1987

700 -

600

500 -

400

300

a,

200

100

0

48^96^144^192^240

Time after administration 191

288^ 0^48^96^144^192^240^288

Time after administration Eh)

0^48^96^144^192

Time after administration

FIG. 4. Plasma concentrations of clofazimine in ahealthy volunteer following a single oral dose of 200mg (4 x 50 mg) after breakfast plotted versus time inlinear plot (A) and semi-logarithmic plot (B).

The mean concentration—time curve ob-tained after the single dose with breakfast(Fig. 3) was fitted by a sum of three expo-nential functions, and the correspondenceof the fitted curve with the experimentalvalues is shown in Figure 5. This functionwas used to predict the trough concentra-tions as well as the plasma concentration

FIG. 5. Mean plasma concentrations of clofaziminefollowing a single oral dose of 200 mg in healthy vol-unteers simulated by a triexponential function. (•) =mean experimental values (N = 3); (—) = triexpo-nential equation: C(t) =^+^+ A3eA, = –1700 pmol/g, X, = 0.3 hr '; A. = 1325 pmol/g, X, = 0.09 hr '; A, = 106 pmol/g, X, = 0.00275 hr.

profile after the last daily dose of multipledosing.

Multiple-dose experiment. The concen-trations of clofazimine in plasma were mea-sured during repeated oral administrationof 50 mg of clofazimine per day for 8 days.In Figure 6 are shown the mean concentra-tions from three subjects measured just be-fore ingestion of the daily dose on days 1,3, 5, and 8 as well as the entire profile afterthe last dose (day 8). The predicted curveusing the fitted sum of three exponentialsobtained from the single-dose experimentis also depicted in Figure 6. There is verygood agreement of the simulated curve withthe trough concentrations on days 3, 5, and8 on one side and with the elimination phaseon days 9 through 19 on the other side.

TABLE 2. Descriptive pharmacokinetic parameters obtained after administration of asingle oral dose of 200 mg (4 X 50 mg) of clofazimine with and without breakfast in threehealthy volunteers.

Subject no.

Clofazimine in plasma

With breakfast Fasted

AUC(0-264 hr)(nmol.hr/g)

Cmax(pmol/g)

Tmax(hr)

AUC(0-264 hr)(nmol hr/g)

Cmax(pmol/g)

Tmax(hr)

1

3Mean ± S.D.

38.521.427.3

29.1 ± 8.7

594434783

604 ± 175

12888'

17.422.713.8

18.0 ± 4.5

421400586

469 ± 102

812

12'

Median.

h0

a

AUCAccumulation factor R =^ss _

4.85

AUC 1

55, 1^Schaad-Lanyi, et al.: Pharmacokinetics of Clofazindne^13

0^3^6^9^12^15^

18

Time^[days]

FIG. 6. Comparison between the observed meanplasma clofazimine concentrations after 50 mg once a

day for 8 days in healthy volunteers and the predictedconcentrations based on single-dose pharmacokinetic

values. (6) = mean experimental values (N = 3).

DISCUSSIONThe kinetics of clofazimine in plasma fol-

lowing a single oral dose of 200 mg of clo-fazimine was similar to that reported pre-viously (Fig. 2) (7). After reaching the peakat 8-12 hr, the plasma concentrations de-clined biexponentially. This suggests a dis-tribution of clofazimine from the centralcompartment to a peripheral compartment,followed by a slow re-equilibration to thecentral compartment from where the drugis eliminated (Fig. 4). The correspondingmean elimination half-life was 10.6 ± 4.0days (±S.D., N = 6). The dotted line inFigure 4B extrapolated to time zero inter-sects the concentration—time curve, thusshowing that absorption is faster than dis-tribution of clofazimine.

Administration of clofazimine to healthyvolunteers together with food containing fatand proteins resulted in a 62% higher bio-availability compared to administration tothe fasted volunteers (Fig. 3). Also, the peakplasma concentrations were higher, and thetime to reach the peak was shorter when thedose was given concomitantly with food.

The plasma concentrations of clofazi-mine measured immediately before admin-istering the 50-mg dose on days 3, 5, and 8of repeated dosing indicate that on day 8the steady-state level had not yet beenreached (Fig. 6). This finding is consistentwith the long elimination half-life of about10 days estimated from the single-dose ex-periments. Thus, plasma concentrationsfollowing multiple dosing are predictable inhealthy volunteers from single-dose kinet-ics, provided that the pharmacokinetics ofclofazimine is linear. An indication of thelinearity of the kinetics of clofazimine canbe obtained from the multiple-dose exper-iment and from the apparent dose—AUC re-lationship observed in a previous study (()•In fact, there is good agreement of the pre-dicted multiple-dose curve, which has beencalculated on the basis of parameters fromthe single-dose experiment (Fig. 5), with thetrough concentrations on days 3, 5, and 8,as well as with the elimination phase ondays 9 through 19 (Fig. 6). It is only thepeak concentration on day 8 which has notbeen adequately predicted. This may be due

0^10^20^30^40^

50^

60Duration of treatment [days]

FIG. 7. Predicted clofazimine plasma concentrations following single daily oral doses of 50 mg.

600

400

200

0

14^ International Journal qf Leprosy^ 1987

to the inter-individual variation in the rateof absorption of clofazimine.

The terminal elimination half-life of clo-fazimine, calculated after the last 50-mg doseof repeated administration, was 8.8 ± 1.0days (mean ± S.D., N = 3), i.e., similar tothat determined after the single 200-mg dose.The half-life obtained from the fitted meanmultiple-dose profile was 10.5 days.

The slow elimination of clofazimine hasits implications for the treatment regimenin patients. When an oral dose of 50 mg ofclofazimine is given daily, it is only after 30days that the concentrations of clofaziminein plasma will come close to steady-statevalues (Fig. 7). The ratio AUC„:AUC, =4.85 may be used to express accumulation(( and Fig. 7). This slow accumulation to-ward the steady state could only be avoidedby giving higher loading doses at the begin-ning of treatment followed by daily admin-istration of the maintenance dose.

SUMMARYThe pharmacokinetics of clofazimine was

evaluated in 12 healthy male volunteers fol-lowing single and multiple oral doses of clo-fazimine. Six volunteers received a singledose of 200 mg together with food. A 200-mg dose was administered to three volun-teers either with or without food. In a mul-tiple-dose experiment, three volunteers wererepeatedly dosed with 50 mg per day to-gether with food for 8 days.

Following a single oral dose of 200 mg,the mean peak plasma concentration of clo-fazimine was 861 ± 289 pmol/g (±S.D.,N = 6) after 8 hr (median). The mean ter-minal half-life was 10.6 ± 4.0 days. Com-parison of the bioavailability of clofazimineadministered with or without food revealeda 60% higher mean area under the curve(AUC) value and a 30% higher mean max-imum concentration (Cmax) value with food(N = 3). The median of times to peak (Tmax)was 8 hr with food and 12 hr without food.

In the multiple-dose study, good agree-ment was found between the mean experi-mental plasma concentration values and theplasma concentration profile predicted fromthe single-dose pharmacokinetics. Theelimination half-life calculated from the ter-minal phase of the individual profiles afterthe last dose was 8.8 ± 1.0 days (±S.D.,

N = 3).The half-life obtained from the fittedmean multiple-dose profile was 10.5 days.

The slow elimination of clofazimine hasits implications for the treatment regimenin patients. To avoid the long-lasting ac-cumulation toward the steady state, higherdaily loading doses are recommended at thebeginning of therapy followed by a dailymaintenance dose.

RESUMENSc valor° la farmacocinetica de la clolazimina en 12

voluntarios sanos que recibieron una o multiples dosis°rules de la droga. Seis voluntarios recibieron una soladosis de 200 mg junto con comida. Tres voluntariosrecibieron una dosis de 200 mg con o sin comida. Enun experiment° con dosis multiples, 3 voluntarios re-cibicron 50 mg por dia junto con comida durante 8dias.

Despues de una sola dosis oral de 200 mg, la con-centraciOn maxima promedio de clofazimina en plas-ma fue de 861 ± 289 pmol/g (±D.E., N = 6) a las 8horas. La vida media terminal de la droga fue de 10.6 ±4.0 dias. La comparaciOn de la bioaccesibilidad de laclofazimina administrada con o sin aliment° revel° unarea media bajo la curva 60% menor y una concentra-ciOn media 30% mayor, cuando la droga se administr°con aliment° (N = 3). La mediana del tiempo de ma-xima concentraciOn (Tmax) fue de 8 horas con comiday de 12 horas sin ella.

En el estudio con dosis multiples, Sc encontr° buenaconcordancia entre los valores medios de la concen-traciOn plasmatica experimental y los valores de con-centraciOn calculados de la farmacocinetica con dosisUnicas. El tiempo de eliminaciOn media calculado dela lase terminal después de la Ultima dosis fue de 8.8 ±1.0 dias (±D.S., N = 3); el tiempo obtenido a partirdel perlil de eliminaciOn promedio administrando do-sis mUltiples rue de 10.5 dias.

Debido a la lenta eliminaciOn de la clofazimina, paraevitar la acumulaciOn prolongada de la droga durantela etapa de mantenimiento se recomienda administrardosis altas al principio de la terapia y despues las dosisdiarias de mantenimiento.

RÈSUMÈ

Chez 12 volontaires masculins en bonne sante., on aevalue la pharmacocinetique de la clofazimine a la suitede doses simples ou multiples de clofazimine, admi-nistrees par voie oralc. Six volontaires ont recu unedose unique de 200 mg dans les aliments. Une dosede 200 mg a ete administthe a trois volontaires, avecou sans aliments. Dans un essai de posologie repetee,trois volontaires ont recu 50 mg par jour, dans lesaliments, pendant 8 jours.

A la suite d'une dose orale unique de 200 mg, lavaleur maximale moyenne des concentrations plas-

55, 1^Schaad-Lanyi, et al.: Pharmacokinetics of Clofazimine^15

matiques de clofazimine a ete de 861 ± 289 pmol/g(±S.D., N = 6) apres 8 heures (mediane). La demi-periode terminale moyenne etait de 10,6 ± 4,0 jours.Une comparaison de la biodisponibilite de la clofazi-mine administree avec ou sans aliments a montre unesurface moyenne de 60% plus etendue sous la courbedes valeurs (AUC), ct unc concentration maximalemoyenne plus &Icy& de 30% (Cmax) avec aliments(N = 3). La mediane des periodes necessaires pour at-teindre la concentration maximale (Tmax) etait de 8heures avec aliments et de 12 heures sans aliments.

Dans l'étude =nee avec des doses repetees, on aobserve une concordance satisfaisante entre les valeursmoyennes de concentration plasmatique experimen-tale, et les profils de concentration plasmatique preditsa la suite d'experiences de pharmacocinetique meneesavec une dose unique. La demi-periodecalculee ft partir de la phase terminale des profils in-dividuels apres la derniere dose, etait de 8,8 ± 1,0jours (± S.D., N = 3). La demi-periode obtenue ft partirdes profits moyens ajustés lors de doses multiples lissesetait de 10,5 jours.

L'elimination lente de la clofazimine a des impli-cations pour la posologie therapeutique a utiliser chezles =lades. En vue d'eviter unc accumulation prolon-g& qui aboutirait a un plateau, on recommande d'ad-ministrer des doses quotidiennes plus elevees au debutde la therapeutique, ces doses devant etre cnsuite sui-vies par une dose de maintien quotidienne.

Acknowledgments. We thank Miss J. Burger for skill-ful technical assistance, and Mr. R. Ackermann forassistance in computing. Parts of this paper were pre-sented at the XII International Leprosy Congress, NewDelhi, India, 1984.

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