Europ. J.clin.Pharmacol. 9, 397-403 (1976) © by Springer-Verlag 1976
Comparative Clinical Pharmacology of Intravenous Cefoxitin and Cephalothin P. F. Sonneville, R. R. Kartodirdjo, H. Skeggs, A. E. Till and C. M. Martin St. Anna Hospital, Venray, Holland, West Point, Pennsylvania, U.S.A.
Received:
July
11,
1975, accepted:
and Merck Sharp and Dohme Research Laboratories,
October
2, 1975
Intravenous doses of 0.5, I, and 2 g cephalothin and cefoxitin, a semisynthetic cephamycin antibiotic highly resistant to bacterial cephalosporinase, were infused over a period of 3 minutes into 18 normal adult males by a randomized, crossover design. Serum and urine data on cefoxitin best fit a two-compartment open model. Serum concentrations following cefoxitin were higher and more prolonged and urine recoveries higher than those following equal doses of cephalothin. The terminal serum half-life of cefoxitin was longer at all dose levels. Renal clearance of cephalothin-like activity exceeded that of cefoxitin, which may possess dosedependent kinetics. Whereas cephalothin has been reported to metabolize by >35% to the less active desacetyl form, cefoxitin was metabolized by O.1 to 6% to the descarbamyl form in individual subjects. Summary.
Key words: Cefoxitin, cephalothin, desacetylcephalothin.
cephamycin,
Cefoxitin is a new semi-synthetic cephamycin antibiotic. Its structure closely resembles that of the cephalosporin antibiotic cephalothin (Fig. I), with two significant differences: a methoxy group (rather than a hydrogen atom) in the 7-a position, and a carbamoyloxy (rather than acetoxy) substituent at the C3-methyl position. Possession of the 7-~-methoxy substituent confers upon cefoxitin a high degree of resistance to inactivation by bacterial cephalosporinases (1,2), the class of beta-lactamases which constitutes a major m e c h a n i s m of bacterial resistance to the cephalosporin antibiotics (3). As a result, the antibacterial spectrum of cefoxitin is considerably broader than that of currently available cephalosporins (4, 5). Active against virtually all strains of bacterial species which are sensitive to the cephalosporins (6), cefoxitin is also highly active against bacterial species which, by virtue of cephalosporinase production, have characteristically been cephalosporin-resistant--
cephalosporinase,
descarbamylcefoxitin,
Serratia marcescens, i n d o l e - p o s i t i v e Proteus, Pro~dencia, and anaerobic gram-negative
rods such as Bacteroides fra~lis (I, 6). Moreover, cefoxitin is active against the large majority of cephalosporinaseproducing, cephalosporin-resistant
0
OCH3
COOH CEFOXITIN
c.2 NH
sh L__',
0//
0
i I
"~".....~
fl CH 2 - O- C- C H ~,
COOH CEPHALOTHIN
Fig. 1. C h e m i c a l cephalothin
structures
of c e f o x i t i n
a n d of
398
strains of common p a t h o g e n i c species of g r a m - n e g a t i v e rods--Escherichia coli, Klebsiella, and i n d o l e - n e g a t i v e Proteus (57)--the p r e v a l e n c e of w h i c h has been steadily rising in the p a s t decade (8). This study was d e s i g n e d to d e t e r m i n e the clinical p h a r m a c o l o g i c p r o p e r t i e s of intravenous c e f o x i t i n and to compare them with those of intravenous cephalothin.
MATERIAL
AND M E T H O D S
Collection of Specimens for Antibiotic Assay
Specimens of blood were o b t a i n e d before and at intervals after each infusion. Urine o u t p u t was m e a s u r e d and samples taken hourly up to 4 hours, and then the sample p a s s e d up to 12 hours after the i n f u s i o n was collected. The blood was a l l o w e d to clot at room temperature; the serum was r e m o v e d s t e r i l e l y and, w i t h aliquots of the urine samples, was stored at -2OOC until just prior to assay. A n t i b i o t i c assays were p e r f o r m e d at the M e r c k Sharp and Dohme R e s e a r c h L a b o r a t o r i e s , W e s t Point, Pa.
Study Drugs
S o d i u m c e f o x i t i n for i n j e c t i o n was supplied in vials c o n t a i n i n g the e q u i v a l e n t of I g of cefoxitin. Immed i a t e l y b e f o r e i n j e c t i o n each vial was r e c o n s t i t u t e d w i t h 10 ml sterile d i s t i l l e d water. Vials of c e p h a l o t h i n sodium (Keflin, Eli Lilly Co.), containing the e q u i v a l e n t of I g of cephalothin, were s i m i l a r l y r e c o n s t i tuted. Volunteer Subjects
E i g h t e e n normal adult males, either students or h o s p i t a l employees, participated in the study. None r e v e a l e d c l i n i c a l or l a b o r a t o r y e v i d e n c e of renal, hepatic, cardiac, p u l m o n a r y , hematologic, or i n f e c t i o u s diseases. The 18 v o l u n t e e r s were listed in order of weight, and using a system of r a n d o m p e r m u t a t i o n in sets of two, were assigned to receive either c e f o x i t i n or cephalothin. The m e a n w e i g h t of those r e c e i v i n g c e f o x i t i n was 72.4 kg, and of those r e c e i v i n g cephalothin, 74.7 kg. The m e m b e r s of each g r o u p r e c e i v e d their a s s i g n e d a n t i b i o t i c i n t r a v e n o u s l y in the f a s t i n g state in doses of 0.5, I, and 2 g at w e e k l y i n t e r v a l s for three weeks. A n t i b i o t i c was a d m i n i s t e r ed over a p e r i o d of three minutes; the order of dosage a d m i n i s t r a t i o n s was r a n d o m i z e d and balanced. I m m e d i a t e l y prior to each dose of a n t i b i o t i c and two days afterward, blood and urine samples were taken for safety studies in H o l l a n d and in the U.S.A. Urine specimens were e x a m i n e d for the p r e s e n c e of leucocytes, erythrocytes, casts, protein, and glucose, and their pH and specific g r a v i t y determined. The following h e m a t o l o g i c a l and b i o c h e m i c a l p a r a m e t e r s were determined: hematocrit, hemoglobin, e r y t h r o c y t e m o r p h o l o g y , platelets, n u m b e r s and dist r i b u t i o n of b l o o d leucocytes, serum creatinine, blood urea nitrogen, SGOT, SGPT, a l k a l i n e phophatase, total bilirubin, and LDH.
Antibiotic Assay
Cefoxitin cup plate
a c t i v i t y was m e a s u r e d by the d i f f u s i o n t e c h n i q u e (9) using Staphylococcus aureus MB 2876 as the test organism. N u t r i e n t agar I s u p p l e m e n t e d w i t h 0.2% yeast e x t r a c t 2 was used for both the 15 ml base and 4 ml seed layers. The r e f e r e n c e standard was at a c o n c e n t r a t i o n of 5 ~g/ml. In the assays of serum, p o o l e d human serum was used to dilute b o t h standards and samples. In urine assays, standards and samples w e r e d i l u t e d w i t h pH 6.0 p h o s p h a t e buffer. A m o d i f i e d Shaw cup d i s p e n s e r was used to drop 6 e v e n l y spaced c y l i n d e r s on each assay plate. Seeded, cupped plates were r e f r i g e r a t e d until samples w e r e i n t r o d u c e d into cups. Three cups on d u p l i c a t e plates were filled alternately with each sample d i l u t i o n and r e f e r e n c e standard. After i n c u b a t i o n of the plates at 37Oc for 18 hours, the cups were removed, and the plates kept r e f r i g e r a t e d until m e a s u r e m e n t of the d i a m e t e r of the zones of i n h i b i t i o n was m a d e using a F i s h e r - L i l l y a n t i b i o t i c zone reader. A c t i v i t y of the samples was c a l c u l a t e d in terms of the standard activity. C e p h a l o t h i n samples were a s s a y e d in a similar m a n n e r except that the test o r g a n i s m was Staphylococcus aureus ATCC 6538P. The r e f e r e n c e standard for serum was 2 ~g/ml and for urine, I ~g/ml. Assay of Urinary Metabolites 3
S e l e c t e d specimens of urine were assayed for c e f o x i t i n and its d e a c y l a t e d metabolite, d e s c a r b a m y l cefoxitin, by an anion e x c h a n g e liquid c h r o m a t o g r a p h y t e c h n i q u e (10) at pH 5 to 6 on DuPont
i Difco Laboratories, Detroit, Michigan, U.S.A. 2 General Biochemlcals, Chagrin Falls, Ohio, U.S.A. 3 Kindly performed by Dr. F.J. Wolf and coworkers, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey, U.S.A.
399
SAX resin using a UV monitor and high performance conditions. Quantitation was achieved by reference to a curve prepared with the use of appropriate standard solutions. The method reliably detects concentrations of cefoxitin between 20 and 500 pg/ml. The lower limit of sensitivity for detection of descarbamyl cefoxitin is either 20 ~g/ml or 0.15% of the concentration of concurrently present cefoxitin, whichever is higher. Serum levels of descarbamyl cefoxitin could not be detected by this method.
.~00 ~.00!
= Cefoxitm 0 . - - - - 0 = Cephatolhin
I00
5O
RESULTS I0 Serum
Concentrations
After an infusion of 0.5 g during 3 minutes (Fig. 2) the mean (and range) of peak concentrations 4 of cefoxitin were 47 pg/ml (25-69 pg/ml), and of cephalothin-like antibacterial activity, 37 ~g/ml (29-58 pg/ml) 5. After similar infusions of I g (Fig. 3) the mean (and range) of peak concentrations of cefoxitin were 110 pg/ml (82-131 pg/ml), and of cephalothin-like activity, 72 ug/ml (54-96 pg/ml) 5 Following similar infusions of 2 g (Fig. 4) the mean (and range) of peak
5
I
I ................ 60
I t20
,, •
1 t80
MINUTES AFTER START OF INFUSION Fig. 2. S e r u m c o n c e n t r a t i o n s of c e f o x i t i n -.a n d c e p h a l o t h i n ~o- (mean of 9 v o l u n t e e r s ) following 0.5 g of each intravenously over 3 minutes
300[ 2O0
I ]
=
~, = Cefoxitin
I00
olothin
5O
~ = Cefo~it,n
300 l,l~rl.
=
200
(3-----.-0 = Cepholothin
100
5O
~0
z ~0
5
1
..............
I 60
.....
\
~ ...... 180
~ 120
MINUTES AFTER START OF INFUSION
Fig. 3. S e r u m c o n c e n t r a t i o n s of c e f o x i t i n --a n d e e p h a l o t h i n - o - (mean of 9 v o l u n t e e r s ) following I g of each intravenously over 3 minutes
4 Five
minutes
after
the
start
of i n f u s i o n
0
60
tao
18o
MINUTES AFTER START OF INFUSION Fig. 4. S e r u m c o n c e n t r a t i o n s o f c e f o x i t i n -.a n d c e p h a l o t h i n -o- (mean of 9 v o l u n t e e r s ) f o l l o w i n g 2 g of e a c h i n t r a v e n o u s l y over 3 minutes
400
Table i, Terminal serum h a l f - l i v e s of antibacterial activity (minutes) following 0.5, i, and 2 g intravenous doses of c e f o x i t i n a n d of cephalothin, g i v e n over 3 m i n u t e s
Table 3. R e n a l clearance of a n t i b a c t e r i a l a c t i v i t y following i n t r a v e n o u s c e f o x i t i n and c e p h a l o t h i n (ml/minute/l.73 m2) d Cefoxitin
Cefoxitin Volunteer No.
Cephalothin
Dose, g 0.5
1.0
Volunteer No.
2.0
Dose,
g
0.5
i .O
2.0
Dose, g 0.5 i.O 2.0
5
474.1 375.1 349.3
1
421.2 362.0 262.1
O.5 1 .O 2.0
6
301.1 277.9 211.4
2
3O5.O 325.4 325.0
8
288.0 215.2 214.3
iO
5
53
50
50
i
28
42
70
6
38
61
48
2
48
40
35
8
40
40
70
3a
--
32
iO
55
60
70
4
30
42, 37 a 25
40
12
41
68
60
7
30
45
35
13
45
45
45
9
28
46
45
O.5 1.O 2.0
14
28
50
44
Ii
33
45
40
0.5
15
35
78
65
16
45
38
35
i .O 2.0
18
41
60
55
17
60
26
38
Harmonic Mean
Harmonic 42
59
56
Mean
a V o l u n t e e r No. 3 received, of i g c e p h a l o t h i n
33
by error,
38
40
2 doses
Table 2. P h a r m a c o k i n e t i c p a r a m e t e r s (mean ± standard error) for cefoxitin at 3 dose levels a Tissue Distribution Rate Constants
Elimination Rate Constant
Volume of Distribution
Dose, k12
k21
k13
V1
g
(min-I)
(min-I)
(min-I )
(L)
0.5
.0280±.0029
.O314±.0027
.0526±.0037
7.7±1.0
1.0
.0223±.0018
.0199±.0014
.0520±.0031
6,8±0.4
2.0
.0148±.OO15
.0199±.0016
.0397±.0020
8.0±O.8
a
kl3
3c
404.6,291.6 c 332.0
249.0 150.6 181.4
4
285.7 237.6 333.0
0.5 i.O 2.0
12
313.5 264.8 328.9
7
349.0 450.3 375.0
0.5 i.O 2.0
13
450.4 465.0 297.8
9
432.2 412.O 365.8
0.5 I.O 2.0
14
355.1 235.3 247.0
Ii
104.9 318.4 355.4
0.5 i.O 2.0
15
265.2 300.9 209.9
16
392.6 367.0 293.7
0.5 i.O 2.0
18
290.9 327.7 191.4
17
458.7 540.1 301.3
0.5 i.O 2.0
Mean
331.9 290.3 247.7
Mean
343.7 370.9 327.0
a F i r s t 2 hr after iv infusion b F i r s t hr after iv infusion
Two-compartment model :
[CentralVlCompar=entj I
Cephalothin
VolunRenal VolunRenal teer No. C l e a r a n c e a teer No. C l e a r a n c e b
I Peripheral q-
Compartment
c V o l u n t e e r No. 3 received, of eephalothin, i g
d ~Ulr = [U(t2)_U(tl)]/ ~ 2
by error,
cdt
2 doses
401 Table 4. Mean urinary recovery of cefoxitin and of cephalothin-like antibacterial activity (% of dose) following intravenous infusions of O.5, I, and 2 g of each over 3 minutes HOURS After Start of
Cefoxitin,
Infusion
0.5
i
o-i
53.6
57.1 5 0 . 3
3 9 . 1 42.5
45.2
0-2
71.3
68.2
68.6
42.9
47.0
5o.1
g
Cephalothin,
2
0.5
1
g
2
activity, 44%, 49%, and 52%, r e s p e c tively (Table 4). B e c a u s e of both the higher u r i n a r y r e c o v e r y and the slower rate of u r i n a r y r e c o v e r y of cefoxitin, c o m p a r e d to that of c e p h a l o t h i n (Table 4), s i g n i f i c a n t a n t i b a c t e r i a l concentrations p e r s i s t e d in the urine for longer periods after cefoxitin; with a I g dose, for example, a n t i b i o t i c conc e n t r a t i o n s in the urine s p e c i m e n s 4-12 hours after the dose w e r e > 1 0 ~ g / m l in 0/9 subjects after cephalothin, but in 8/9 after cefoxitin.
0-3
75.0
73.8
73.3
43.6
48.0
51.7
0-4
76.7
75.6
75.5
43.9
48.6
52.0
Urinary Metabolites
o-12
78.1
7 7 . 1 77.6
44.2
48.9
52.3
Studies of selected urine samples suggested that c e f o x i t i n was d e a c y l a t e d to d e s c a r b a m y l c e f o x i t i n p r i n c i p a l l y in the later hours after the dose; in the urines studied the m e a n degree of deac y l a t i o n in the first four hours after a d m i n i s t r a t i o n ranged from 1.6% of a 2 g dose to 4.5% of a 0.5 g dose (Table 5). T r e a t m e n t of selected urine samples with g l u c u r o n i d a s e - s u l f a t a s e failed to reveal e v i d e n c e of m e t a b o l i t e s of c e f o x i t i n e x i s t i n g as g l u c u r o n i d e s or sulfates. Similarly, i n f r a - r e d and u l t r a - v i o l e t a b s o r p t i o n studies of m u l t i p l e urine specimens failed to reveal evidence of c e f o x i t i n fragments with a r u p t u r e d S-lactam ring.
c o n c e n t r a t i o n s of c e f o x i t i n were 221 ~g/ml (119-318 ~g/ml), and of cephalothin-like activity, 164 ~g/ml (128-202 ~g/ml) 5 • T e r m i n a l serum h a l f - l i v e s of cefoxitin and of c e p h a l o t h i n - l i k e activity in each v o l u n t e e r under the three dose c o n d i t i o n s are shown in Table I. M e a n t e r m i n a l serum h a l f - l i v e s of c e f o x i t i n after the 0.5, I, and 2 g doses were, r e s p e c t i v e l y , 42, 59, and 56 minutes, and of c e p h a l o t h i n - l i k e a n t i b a c t e r i a l activity, 33, 38, and 40 minutes, r e s p e c t i v e l y . Serum c o n c e n t r a t i o n s of c e f o x i t i n were best fitted by a t w o - c o m p a r t m e n t open model. P h a r m a c o k i n e t i c p a r a m e t e r s were o b t a i n e d g r a p h i c a l l y from the serum data and the v a l i d i t y of the m o d e l v e r i f i e d by the p r o c e d u r e of Kwan et al. (11). Mean p h a r m a c o k i n e t i c p a r a m e t e r s for each dose of c e f o x i t i n are shown in Table 2. B e c a u s e it is not known w h i c h f r a c t i o n of the c e p h a l o t h i n - l i k e a c t i v i t y observed in specimens of serum and urine o b t a i n e d f o l l o w i n g c e p h a l o t h i n administ r a t i o n r e p r e s e n t s u n c h a n g e d drug and which fraction represents metabolite, p h a r m a c o k i n e t i c m o d e l i n g of c e p h a l o t h i n was not attempted.
volunteer Tolerance
N e i t h e r c e f o x i t i n nor c e p h a l o t h i n p r o d u c e d l a b o r a t o r y e v i d e n c e of a d v e r s e renal, hepatic, o r h e m a t o l o g i c effects. A r e l a t i v e l y high f r e q u e n c y of d e v e l o p m e n t of e l e v a t e d serum lactic dehydrogenase values f o l l o w i n g both c e f o x i t i n (5/20) and c e p h a l o t h i n (5/21) was shown to be a spurious finding, r e l a t e d to v a r i a t i o n in p e r f o r m a n c e of the test. All v o l u n t e e r s were c a r e f u l l y o b s e r v e d for systemic symptoms of h y p o t e n s i o n or feelings of weakness, but none was observed during or after the infusions. The veins used for the infusions showed no signs of phlebitis.
urinary Excretion
Renal c l e a r a n c e of a n t i b a c t e r i a l activity f o l l o w i n g a d m i n i s t r a t i o n of each dose of c e f o x i t i n and of c e p h a l o t h i n is shown in Table 3. A l t h o u g h the m e a n renal c l e a r a n c e of c e f o x i t i n - l i k e antib a c t e r i a l a c t i v i t y a p p e a r e d to fall with i n c r e a s i n g dose, these d i f f e r e n c e s were not s t a t i s t i c a l l y significant. Mean u r i n a r y r e c o v e r i e s of c e f o x i t i n like a c t i v i t y were 78%, 77%, and 78%, r e s p e c t i v e l y , f o l l o w i n g the 0.5, I, and 2 g infusions; and of c e p h a l o t h i n - l i k e
The data in this study show that intravenous doses of c e f o x i t i n p r o d u c e h i g h e r and m o r e p r o l o n g e d serum c o n c e n t r a t i o n s than do equal doses of cephalothin. Since c e f o x i t i n and c e p h a l o t h i n bind e q u a l l y to human p l a s m a p r o t e i n s (50 - 60%)6, this d i f f e r e n c e in serum levels is p r o b a b l y due p r i m a r i l y to the rapid and e x t e n s i v e (>35%) m e t a b o -
5 Data available from authors
6 Miller, A.K.
DISCUSSION
Personal communication
402
Table 5. Cefoxitin and descarbamyl cefoxitin in urine specimens of four subjects. Expressed as per cent of an intravenous dose given over a 3-minute period. Results of liquid chromatographic analysis Subject No. 5
Dose g
Compound O-I
Hours after Dose i-2 2-3 3-4
4-12
Total Recovered 0-4 h O-12 h
0.5
CFX DCFX
66 0.4
15.2 i .I
3.9 i .2
2.5 i .4
N.D. N.D.
87.6 4.1
8
0.5
CFX DCFX
12.5
Comparative Clinical Pharmacology of Intravenous Cefoxitin and Cephalothin P. F. Sonneville, R. R. Kartodirdjo, H. Skeggs, A. E. Till and C. M. Martin St. Anna Hospital, Venray, Holland, West Point, Pennsylvania, U.S.A.
Received:
July
11,
1975, accepted:
and Merck Sharp and Dohme Research Laboratories,
October
2, 1975
Intravenous doses of 0.5, I, and 2 g cephalothin and cefoxitin, a semisynthetic cephamycin antibiotic highly resistant to bacterial cephalosporinase, were infused over a period of 3 minutes into 18 normal adult males by a randomized, crossover design. Serum and urine data on cefoxitin best fit a two-compartment open model. Serum concentrations following cefoxitin were higher and more prolonged and urine recoveries higher than those following equal doses of cephalothin. The terminal serum half-life of cefoxitin was longer at all dose levels. Renal clearance of cephalothin-like activity exceeded that of cefoxitin, which may possess dosedependent kinetics. Whereas cephalothin has been reported to metabolize by >35% to the less active desacetyl form, cefoxitin was metabolized by O.1 to 6% to the descarbamyl form in individual subjects. Summary.
Key words: Cefoxitin, cephalothin, desacetylcephalothin.
cephamycin,
Cefoxitin is a new semi-synthetic cephamycin antibiotic. Its structure closely resembles that of the cephalosporin antibiotic cephalothin (Fig. I), with two significant differences: a methoxy group (rather than a hydrogen atom) in the 7-a position, and a carbamoyloxy (rather than acetoxy) substituent at the C3-methyl position. Possession of the 7-~-methoxy substituent confers upon cefoxitin a high degree of resistance to inactivation by bacterial cephalosporinases (1,2), the class of beta-lactamases which constitutes a major m e c h a n i s m of bacterial resistance to the cephalosporin antibiotics (3). As a result, the antibacterial spectrum of cefoxitin is considerably broader than that of currently available cephalosporins (4, 5). Active against virtually all strains of bacterial species which are sensitive to the cephalosporins (6), cefoxitin is also highly active against bacterial species which, by virtue of cephalosporinase production, have characteristically been cephalosporin-resistant--
cephalosporinase,
descarbamylcefoxitin,
Serratia marcescens, i n d o l e - p o s i t i v e Proteus, Pro~dencia, and anaerobic gram-negative
rods such as Bacteroides fra~lis (I, 6). Moreover, cefoxitin is active against the large majority of cephalosporinaseproducing, cephalosporin-resistant
0
OCH3
COOH CEFOXITIN
c.2 NH
sh L__',
0//
0
i I
"~".....~
fl CH 2 - O- C- C H ~,
COOH CEPHALOTHIN
Fig. 1. C h e m i c a l cephalothin
structures
of c e f o x i t i n
a n d of
398
strains of common p a t h o g e n i c species of g r a m - n e g a t i v e rods--Escherichia coli, Klebsiella, and i n d o l e - n e g a t i v e Proteus (57)--the p r e v a l e n c e of w h i c h has been steadily rising in the p a s t decade (8). This study was d e s i g n e d to d e t e r m i n e the clinical p h a r m a c o l o g i c p r o p e r t i e s of intravenous c e f o x i t i n and to compare them with those of intravenous cephalothin.
MATERIAL
AND M E T H O D S
Collection of Specimens for Antibiotic Assay
Specimens of blood were o b t a i n e d before and at intervals after each infusion. Urine o u t p u t was m e a s u r e d and samples taken hourly up to 4 hours, and then the sample p a s s e d up to 12 hours after the i n f u s i o n was collected. The blood was a l l o w e d to clot at room temperature; the serum was r e m o v e d s t e r i l e l y and, w i t h aliquots of the urine samples, was stored at -2OOC until just prior to assay. A n t i b i o t i c assays were p e r f o r m e d at the M e r c k Sharp and Dohme R e s e a r c h L a b o r a t o r i e s , W e s t Point, Pa.
Study Drugs
S o d i u m c e f o x i t i n for i n j e c t i o n was supplied in vials c o n t a i n i n g the e q u i v a l e n t of I g of cefoxitin. Immed i a t e l y b e f o r e i n j e c t i o n each vial was r e c o n s t i t u t e d w i t h 10 ml sterile d i s t i l l e d water. Vials of c e p h a l o t h i n sodium (Keflin, Eli Lilly Co.), containing the e q u i v a l e n t of I g of cephalothin, were s i m i l a r l y r e c o n s t i tuted. Volunteer Subjects
E i g h t e e n normal adult males, either students or h o s p i t a l employees, participated in the study. None r e v e a l e d c l i n i c a l or l a b o r a t o r y e v i d e n c e of renal, hepatic, cardiac, p u l m o n a r y , hematologic, or i n f e c t i o u s diseases. The 18 v o l u n t e e r s were listed in order of weight, and using a system of r a n d o m p e r m u t a t i o n in sets of two, were assigned to receive either c e f o x i t i n or cephalothin. The m e a n w e i g h t of those r e c e i v i n g c e f o x i t i n was 72.4 kg, and of those r e c e i v i n g cephalothin, 74.7 kg. The m e m b e r s of each g r o u p r e c e i v e d their a s s i g n e d a n t i b i o t i c i n t r a v e n o u s l y in the f a s t i n g state in doses of 0.5, I, and 2 g at w e e k l y i n t e r v a l s for three weeks. A n t i b i o t i c was a d m i n i s t e r ed over a p e r i o d of three minutes; the order of dosage a d m i n i s t r a t i o n s was r a n d o m i z e d and balanced. I m m e d i a t e l y prior to each dose of a n t i b i o t i c and two days afterward, blood and urine samples were taken for safety studies in H o l l a n d and in the U.S.A. Urine specimens were e x a m i n e d for the p r e s e n c e of leucocytes, erythrocytes, casts, protein, and glucose, and their pH and specific g r a v i t y determined. The following h e m a t o l o g i c a l and b i o c h e m i c a l p a r a m e t e r s were determined: hematocrit, hemoglobin, e r y t h r o c y t e m o r p h o l o g y , platelets, n u m b e r s and dist r i b u t i o n of b l o o d leucocytes, serum creatinine, blood urea nitrogen, SGOT, SGPT, a l k a l i n e phophatase, total bilirubin, and LDH.
Antibiotic Assay
Cefoxitin cup plate
a c t i v i t y was m e a s u r e d by the d i f f u s i o n t e c h n i q u e (9) using Staphylococcus aureus MB 2876 as the test organism. N u t r i e n t agar I s u p p l e m e n t e d w i t h 0.2% yeast e x t r a c t 2 was used for both the 15 ml base and 4 ml seed layers. The r e f e r e n c e standard was at a c o n c e n t r a t i o n of 5 ~g/ml. In the assays of serum, p o o l e d human serum was used to dilute b o t h standards and samples. In urine assays, standards and samples w e r e d i l u t e d w i t h pH 6.0 p h o s p h a t e buffer. A m o d i f i e d Shaw cup d i s p e n s e r was used to drop 6 e v e n l y spaced c y l i n d e r s on each assay plate. Seeded, cupped plates were r e f r i g e r a t e d until samples w e r e i n t r o d u c e d into cups. Three cups on d u p l i c a t e plates were filled alternately with each sample d i l u t i o n and r e f e r e n c e standard. After i n c u b a t i o n of the plates at 37Oc for 18 hours, the cups were removed, and the plates kept r e f r i g e r a t e d until m e a s u r e m e n t of the d i a m e t e r of the zones of i n h i b i t i o n was m a d e using a F i s h e r - L i l l y a n t i b i o t i c zone reader. A c t i v i t y of the samples was c a l c u l a t e d in terms of the standard activity. C e p h a l o t h i n samples were a s s a y e d in a similar m a n n e r except that the test o r g a n i s m was Staphylococcus aureus ATCC 6538P. The r e f e r e n c e standard for serum was 2 ~g/ml and for urine, I ~g/ml. Assay of Urinary Metabolites 3
S e l e c t e d specimens of urine were assayed for c e f o x i t i n and its d e a c y l a t e d metabolite, d e s c a r b a m y l cefoxitin, by an anion e x c h a n g e liquid c h r o m a t o g r a p h y t e c h n i q u e (10) at pH 5 to 6 on DuPont
i Difco Laboratories, Detroit, Michigan, U.S.A. 2 General Biochemlcals, Chagrin Falls, Ohio, U.S.A. 3 Kindly performed by Dr. F.J. Wolf and coworkers, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey, U.S.A.
399
SAX resin using a UV monitor and high performance conditions. Quantitation was achieved by reference to a curve prepared with the use of appropriate standard solutions. The method reliably detects concentrations of cefoxitin between 20 and 500 pg/ml. The lower limit of sensitivity for detection of descarbamyl cefoxitin is either 20 ~g/ml or 0.15% of the concentration of concurrently present cefoxitin, whichever is higher. Serum levels of descarbamyl cefoxitin could not be detected by this method.
.~00 ~.00!
= Cefoxitm 0 . - - - - 0 = Cephatolhin
I00
5O
RESULTS I0 Serum
Concentrations
After an infusion of 0.5 g during 3 minutes (Fig. 2) the mean (and range) of peak concentrations 4 of cefoxitin were 47 pg/ml (25-69 pg/ml), and of cephalothin-like antibacterial activity, 37 ~g/ml (29-58 pg/ml) 5. After similar infusions of I g (Fig. 3) the mean (and range) of peak concentrations of cefoxitin were 110 pg/ml (82-131 pg/ml), and of cephalothin-like activity, 72 ug/ml (54-96 pg/ml) 5 Following similar infusions of 2 g (Fig. 4) the mean (and range) of peak
5
I
I ................ 60
I t20
,, •
1 t80
MINUTES AFTER START OF INFUSION Fig. 2. S e r u m c o n c e n t r a t i o n s of c e f o x i t i n -.a n d c e p h a l o t h i n ~o- (mean of 9 v o l u n t e e r s ) following 0.5 g of each intravenously over 3 minutes
300[ 2O0
I ]
=
~, = Cefoxitin
I00
olothin
5O
~ = Cefo~it,n
300 l,l~rl.
=
200
(3-----.-0 = Cepholothin
100
5O
~0
z ~0
5
1
..............
I 60
.....
\
~ ...... 180
~ 120
MINUTES AFTER START OF INFUSION
Fig. 3. S e r u m c o n c e n t r a t i o n s of c e f o x i t i n --a n d e e p h a l o t h i n - o - (mean of 9 v o l u n t e e r s ) following I g of each intravenously over 3 minutes
4 Five
minutes
after
the
start
of i n f u s i o n
0
60
tao
18o
MINUTES AFTER START OF INFUSION Fig. 4. S e r u m c o n c e n t r a t i o n s o f c e f o x i t i n -.a n d c e p h a l o t h i n -o- (mean of 9 v o l u n t e e r s ) f o l l o w i n g 2 g of e a c h i n t r a v e n o u s l y over 3 minutes
400
Table i, Terminal serum h a l f - l i v e s of antibacterial activity (minutes) following 0.5, i, and 2 g intravenous doses of c e f o x i t i n a n d of cephalothin, g i v e n over 3 m i n u t e s
Table 3. R e n a l clearance of a n t i b a c t e r i a l a c t i v i t y following i n t r a v e n o u s c e f o x i t i n and c e p h a l o t h i n (ml/minute/l.73 m2) d Cefoxitin
Cefoxitin Volunteer No.
Cephalothin
Dose, g 0.5
1.0
Volunteer No.
2.0
Dose,
g
0.5
i .O
2.0
Dose, g 0.5 i.O 2.0
5
474.1 375.1 349.3
1
421.2 362.0 262.1
O.5 1 .O 2.0
6
301.1 277.9 211.4
2
3O5.O 325.4 325.0
8
288.0 215.2 214.3
iO
5
53
50
50
i
28
42
70
6
38
61
48
2
48
40
35
8
40
40
70
3a
--
32
iO
55
60
70
4
30
42, 37 a 25
40
12
41
68
60
7
30
45
35
13
45
45
45
9
28
46
45
O.5 1.O 2.0
14
28
50
44
Ii
33
45
40
0.5
15
35
78
65
16
45
38
35
i .O 2.0
18
41
60
55
17
60
26
38
Harmonic Mean
Harmonic 42
59
56
Mean
a V o l u n t e e r No. 3 received, of i g c e p h a l o t h i n
33
by error,
38
40
2 doses
Table 2. P h a r m a c o k i n e t i c p a r a m e t e r s (mean ± standard error) for cefoxitin at 3 dose levels a Tissue Distribution Rate Constants
Elimination Rate Constant
Volume of Distribution
Dose, k12
k21
k13
V1
g
(min-I)
(min-I)
(min-I )
(L)
0.5
.0280±.0029
.O314±.0027
.0526±.0037
7.7±1.0
1.0
.0223±.0018
.0199±.0014
.0520±.0031
6,8±0.4
2.0
.0148±.OO15
.0199±.0016
.0397±.0020
8.0±O.8
a
kl3
3c
404.6,291.6 c 332.0
249.0 150.6 181.4
4
285.7 237.6 333.0
0.5 i.O 2.0
12
313.5 264.8 328.9
7
349.0 450.3 375.0
0.5 i.O 2.0
13
450.4 465.0 297.8
9
432.2 412.O 365.8
0.5 I.O 2.0
14
355.1 235.3 247.0
Ii
104.9 318.4 355.4
0.5 i.O 2.0
15
265.2 300.9 209.9
16
392.6 367.0 293.7
0.5 i.O 2.0
18
290.9 327.7 191.4
17
458.7 540.1 301.3
0.5 i.O 2.0
Mean
331.9 290.3 247.7
Mean
343.7 370.9 327.0
a F i r s t 2 hr after iv infusion b F i r s t hr after iv infusion
Two-compartment model :
[CentralVlCompar=entj I
Cephalothin
VolunRenal VolunRenal teer No. C l e a r a n c e a teer No. C l e a r a n c e b
I Peripheral q-
Compartment
c V o l u n t e e r No. 3 received, of eephalothin, i g
d ~Ulr = [U(t2)_U(tl)]/ ~ 2
by error,
cdt
2 doses
401 Table 4. Mean urinary recovery of cefoxitin and of cephalothin-like antibacterial activity (% of dose) following intravenous infusions of O.5, I, and 2 g of each over 3 minutes HOURS After Start of
Cefoxitin,
Infusion
0.5
i
o-i
53.6
57.1 5 0 . 3
3 9 . 1 42.5
45.2
0-2
71.3
68.2
68.6
42.9
47.0
5o.1
g
Cephalothin,
2
0.5
1
g
2
activity, 44%, 49%, and 52%, r e s p e c tively (Table 4). B e c a u s e of both the higher u r i n a r y r e c o v e r y and the slower rate of u r i n a r y r e c o v e r y of cefoxitin, c o m p a r e d to that of c e p h a l o t h i n (Table 4), s i g n i f i c a n t a n t i b a c t e r i a l concentrations p e r s i s t e d in the urine for longer periods after cefoxitin; with a I g dose, for example, a n t i b i o t i c conc e n t r a t i o n s in the urine s p e c i m e n s 4-12 hours after the dose w e r e > 1 0 ~ g / m l in 0/9 subjects after cephalothin, but in 8/9 after cefoxitin.
0-3
75.0
73.8
73.3
43.6
48.0
51.7
0-4
76.7
75.6
75.5
43.9
48.6
52.0
Urinary Metabolites
o-12
78.1
7 7 . 1 77.6
44.2
48.9
52.3
Studies of selected urine samples suggested that c e f o x i t i n was d e a c y l a t e d to d e s c a r b a m y l c e f o x i t i n p r i n c i p a l l y in the later hours after the dose; in the urines studied the m e a n degree of deac y l a t i o n in the first four hours after a d m i n i s t r a t i o n ranged from 1.6% of a 2 g dose to 4.5% of a 0.5 g dose (Table 5). T r e a t m e n t of selected urine samples with g l u c u r o n i d a s e - s u l f a t a s e failed to reveal e v i d e n c e of m e t a b o l i t e s of c e f o x i t i n e x i s t i n g as g l u c u r o n i d e s or sulfates. Similarly, i n f r a - r e d and u l t r a - v i o l e t a b s o r p t i o n studies of m u l t i p l e urine specimens failed to reveal evidence of c e f o x i t i n fragments with a r u p t u r e d S-lactam ring.
c o n c e n t r a t i o n s of c e f o x i t i n were 221 ~g/ml (119-318 ~g/ml), and of cephalothin-like activity, 164 ~g/ml (128-202 ~g/ml) 5 • T e r m i n a l serum h a l f - l i v e s of cefoxitin and of c e p h a l o t h i n - l i k e activity in each v o l u n t e e r under the three dose c o n d i t i o n s are shown in Table I. M e a n t e r m i n a l serum h a l f - l i v e s of c e f o x i t i n after the 0.5, I, and 2 g doses were, r e s p e c t i v e l y , 42, 59, and 56 minutes, and of c e p h a l o t h i n - l i k e a n t i b a c t e r i a l activity, 33, 38, and 40 minutes, r e s p e c t i v e l y . Serum c o n c e n t r a t i o n s of c e f o x i t i n were best fitted by a t w o - c o m p a r t m e n t open model. P h a r m a c o k i n e t i c p a r a m e t e r s were o b t a i n e d g r a p h i c a l l y from the serum data and the v a l i d i t y of the m o d e l v e r i f i e d by the p r o c e d u r e of Kwan et al. (11). Mean p h a r m a c o k i n e t i c p a r a m e t e r s for each dose of c e f o x i t i n are shown in Table 2. B e c a u s e it is not known w h i c h f r a c t i o n of the c e p h a l o t h i n - l i k e a c t i v i t y observed in specimens of serum and urine o b t a i n e d f o l l o w i n g c e p h a l o t h i n administ r a t i o n r e p r e s e n t s u n c h a n g e d drug and which fraction represents metabolite, p h a r m a c o k i n e t i c m o d e l i n g of c e p h a l o t h i n was not attempted.
volunteer Tolerance
N e i t h e r c e f o x i t i n nor c e p h a l o t h i n p r o d u c e d l a b o r a t o r y e v i d e n c e of a d v e r s e renal, hepatic, o r h e m a t o l o g i c effects. A r e l a t i v e l y high f r e q u e n c y of d e v e l o p m e n t of e l e v a t e d serum lactic dehydrogenase values f o l l o w i n g both c e f o x i t i n (5/20) and c e p h a l o t h i n (5/21) was shown to be a spurious finding, r e l a t e d to v a r i a t i o n in p e r f o r m a n c e of the test. All v o l u n t e e r s were c a r e f u l l y o b s e r v e d for systemic symptoms of h y p o t e n s i o n or feelings of weakness, but none was observed during or after the infusions. The veins used for the infusions showed no signs of phlebitis.
urinary Excretion
Renal c l e a r a n c e of a n t i b a c t e r i a l activity f o l l o w i n g a d m i n i s t r a t i o n of each dose of c e f o x i t i n and of c e p h a l o t h i n is shown in Table 3. A l t h o u g h the m e a n renal c l e a r a n c e of c e f o x i t i n - l i k e antib a c t e r i a l a c t i v i t y a p p e a r e d to fall with i n c r e a s i n g dose, these d i f f e r e n c e s were not s t a t i s t i c a l l y significant. Mean u r i n a r y r e c o v e r i e s of c e f o x i t i n like a c t i v i t y were 78%, 77%, and 78%, r e s p e c t i v e l y , f o l l o w i n g the 0.5, I, and 2 g infusions; and of c e p h a l o t h i n - l i k e
The data in this study show that intravenous doses of c e f o x i t i n p r o d u c e h i g h e r and m o r e p r o l o n g e d serum c o n c e n t r a t i o n s than do equal doses of cephalothin. Since c e f o x i t i n and c e p h a l o t h i n bind e q u a l l y to human p l a s m a p r o t e i n s (50 - 60%)6, this d i f f e r e n c e in serum levels is p r o b a b l y due p r i m a r i l y to the rapid and e x t e n s i v e (>35%) m e t a b o -
5 Data available from authors
6 Miller, A.K.
DISCUSSION
Personal communication
402
Table 5. Cefoxitin and descarbamyl cefoxitin in urine specimens of four subjects. Expressed as per cent of an intravenous dose given over a 3-minute period. Results of liquid chromatographic analysis Subject No. 5
Dose g
Compound O-I
Hours after Dose i-2 2-3 3-4
4-12
Total Recovered 0-4 h O-12 h
0.5
CFX DCFX
66 0.4
15.2 i .I
3.9 i .2
2.5 i .4
N.D. N.D.
87.6 4.1
8
0.5
CFX DCFX
12.5
