Major biotransformation routes of some allylamine antimycotics


Battig, F.A.; Nefzger, M.; Schulz, G.

Recent trends in the discovery, development and evaluation of antifungal agents: 479-495

1987


The biological fate of 5 radiolabelled allylamine antimycotics, including naftifine and terbinafine, was investigated in man, rat, dog, guinea pig and rabbit. Absorption, distribution, elimination and biotransformation routes were studied. Major biotransformation routes were N-dealkylation; oxidation at aliphatic and aromatic carbon atoms; conjugation with glucuronic acid and glycine and rupture of the carbon-silicon bond in 1 drug; all were based on the structures of identified metabolites.

Recent
Trends
in
the
Discovery,
Development
and
Evaluation
of
Antifungal
Agents.
R.A.
Fromtling
(Ed.)
Copyright
©
1987,
J.R.
Prous
Science
Publishers,
S.A.
MA
OR
BIOTRANSF
ORIVIA
I
(O
ROUTES
OF
SOME
ALLYIIAM
NE
ANTIMYCOTICS
Frank
A.
Battig,
Marijke
Nefzger
and
Gerhard
Schulz
Sandoz
Forschungsinstitut,
Vienna,
Austria
ABSTRACT
The
biological
fate
of
five
radiolabelled
allylamine
antimycotics
has
been
investigated
in
various
laboratory
animals
and,
in
two
cases,
also
in
volunteers.
Described
in
this
paper
are
the
presently
known
biotransfor-
mation
routes
of
these
compounds
based
on
the
structures
of
identified
metabolites.
Major
biotransformation
routes
are
a)
N-dealkylation,
b)
ox-
idation
at
aliphatic
and
aromatic
carbon
atoms,
c)
conjugation
with
glucuronic
acid
and
glycine,
and
d)
rupture
of
the
carbon-silicon
bond
in
the
sila-drug
86-362.
Of
the
investigated
animal
species,
i.e.,
rats,
dogs,
mice,
rabbits
and
guinea
pigs,
the
rabbit
resembles
man
most
closely
both
with
respect
to
the
rate
of
excretion
and
to
the
overall
biotransformation
pattern.
KEY
WORDS:
Allylamine
-
Antimycotic
-
Biotransformation
-
Rat
-
Dog
-
Mouse
-
Guinea
pig
-
Man
-
Rabbit
-
Terbinafine
-
Naftifine
INTRODUCTION
The
allylamine
derivatives
are
a
new
class
of
synthetic
antifungal
agents
(10).
A
large
number
of
compounds
exhibiting
considerable
antimycotic
activity
has
recently
been
synthesized
at
the
Sandoz
Forschungsinstitut
(SFI)
in
Vienna
(14-16).
In
this
paper,
the
presently
known
biotransformation
pathways
of
five
selected
allylamine
antimycotics
are
described
and
discussed.
One
of
them,
naftifine
(Fig.
3)
has
already
been
introduced
into
the
market
as
a
topical
Address
all
correspondence
to:
Dr.
Frank
A.
Battig,
Sandoz
Forschungsinstitut,
Brunner
Strasse
59,
A-1235
Vienna,
Austria.
479
480
F.A.
BATTIG,
M.
NEFZGER
AND
G.
SCHULZ
antifungal
drug.
Terbinafine
3
(Fig.
),
the
successor
compound,
at
pre-
sent
is
undergoing
advanced
clinical
investigation
both
for
oral
and
topical
administration.
The
biological
fate
of
naftifine
and
terbinafine
has
been
extensively
investigated
in
several
animal
species
used
in
toxicity
and
ef-
ficacy
testing,
and
in
volunteers
and
patients
(2,
12,
13).
The
other
com-
pounds
so
far
have
only
been
investigated
in
1-3
animal
species.
MATERIALS
AND
METHODS
Synthesis
of
Radiolabelled
Test
Drugs
All
radiolabelled
synthetic intermediates
and
metabolites
7
(Fig.
3
)
(naphthoic
acid)
and
15
(Fig.
3)
(desmethyl-naftifine)
were
prepared
by
H.
Andres
and
R.
Voges
in
the
Synthetic
Tracer
Laboratories
of
the
Biophar-
maceutical
Department
at
Sandoz,
Basle
(Switzerland).
From
these,
the
final
test
compounds
were
synthesized
either
at
the
Synthetic
Tracer
Laboratories
or
at
the
Radiobiology
Unit
of
the
Biochemistry
Department
at
the
San-
doz
Forschungsinstitut
(SFI)
in
Vienna
by
one
of
the
authors
(F.A.B.)
in
collaboration
with
A.
Stuetz.
Dose
Regimens
and
Radiochemical
Purities
In
the
animal
experiments,
dose
regimens
were
generally
used
for
the
biotransformation
studies
that
had
before
been
used
in
the
relevant
tox-
icological
studies.
In
summary,
the
drugs
were
administered
either
as
solu-
tions
of
the
drug
bases
in
oil
or
in
polyethyleneglycol/water
mixtures,
or
as
solutions
or
suspensions,
in
aqueous
solvents,
of
the
corresponding
hydrochlorides.
Single
doses
were
administered
via
the
oral,
intravenous
or
topical
(rabbit
only)
route.
Multiple
oral
doses
were
administered
at
a
frequency
of
one
dose
per
day
over
a
maximum
of
seven
consecutive
days.
Oral
and
topical
doses
ranged
from
30
to
300
mg/kg
b.w.,
while
intravenous
doses
were
restricted
to
1
to
5
mg/kg
b.w.
The
radiochemical
purity
of
the
administered
test
drugs
was
normally
better
than
97%.
In
studies
on
the
biological
fate
of
radiolabelled
naftifine
and
terbinafine
in
volunteers,
therapeutically
relevant
doses
and
routes
of
administration
were
employed.
The
radiochemical
purity
was
always
better
than
98%.
Summarized
in
Table
1
are
the
structures
of
all
the
radiolabelled
allylamine
antimycotics
and
the
species
so
far
investigated
with
respect
to
major
biotransformation
routes
and/or
absorption,
distribution
and
ex-
cretion
(ADE)
of
total
radioactivity.
Note:
Throughout
the
text,
numbers
in
italics
(e.g.,
1,
3)
refer
to
chemical
structures
that
may
be
found
in
the
Figures;
BIOTRANSFORMATION
OF
ALLYLAMINES
481
Analysis
of
Metabolic
Patterns
The
qualitative
and
quantitative
distribution
of
radiolabelled
metabolites
in
biological
samples
was
determined
by
means
of
analytical
reverse
phase
HPLC
with
either
on-line
radioactivity
measurement
using
a
flow-through
radioactivity
detector,
or
off-line
by
counting
eluent
fractions
in
a
stationary
liquid
scintillation
counter.
A
computer
program
optimized
by
F.
Schmook
and
T.
Gramanitsch
allowed
automatic
transformation
of
retention
times
and
0
7o
proportions
of
individual
metabolites
on
total
sample
radioactivity
into
complete
on-line
(Fig.
1)
or
«synthetic»
off-line
(Fig.
2)
radio-
chromatograms.
1
0
0
c4
ri
r
I
(
R=g
lu
curon
ic
•c
i
d)
40
Rat
plasma
(at
2h)
Parent
Drug
(3)
Rat
urine
(0-48h)
40
Ls
ti
48
Parent
Drug
(3)
Rat
bile
(0-48h)
0 )
)
j
Parent
Drug
(9)
14
`
•"
"
•4"."
0/44.446.444
4044
A--
,
Chromatographic
Retention
--v.
Figure
1
Typical
'on-line'
metabolic
patterns
in
plasma,
urine
and
bile
of
rats
after
oral
administration
of
("C)
Terbinafine.
482
F.A.
BATTIG,
M.
NEFZGER
AND
0.
SCHULZ
Time
after
dosing
:
lh
+>
0
0
0
11
1
111.1.
ego
.1
s
1
.1.
..111.1
.11.0.1111s.
4h
11.11111111..1111,111111..
.1..1111.
36h
1
1,1111.111
1.
.1.1
...lull
11.111.,a,
11411
11
Is
21
l•
,1•
11
11
Fraction
Number
Figure
2
Typical
'synthetic
off-line'
metabolic
patterns
in
plasma
samples
of
a
male
volunteer
after
oral
administration
of
250
mg
(
14
C)
Terbinafine.
Isolation
and
Purification
of
Metabolites
Normally,
metabolites
were
isolated
from
urine.
In
some
cases
bile
was,
however,
additionally
used
as
a
suitable
source
of
metabolites
not
present
in
urine
in
sufficient
amounts.
Metabolites
were
concentrated
and
purified
using
one,
or
combinations
of
two,
of
the
following
procedures:
—Solvent
extractions
into
butylacetate
at
acidic
pH,
followed
by
back-
extraction
into
aqueous
buffers
at
alkaline
pH.
BIOTRANSFORMATION
OF
ALLYLAMINES
483
—Adsorption
onto
Amberlite
XAD-
2
resin
followed
by
semi-fractioned
desorption
using
step-gradients
of
aqueous
buffers
containing
increasing
proportions
of
methanol.
—Absorption
onto
and
fractionated
elution
from Lobar
RP-8
reverse
phase
columns
of
43
to
60µm
particle
diameter
(Merck,
Darmstadt)
using
gradients
from
aqueous
buffers
to
unbuffered
methanol.
Final
purification
was
usually
achieved
by
means
of
preparative
HPLC
using
C-8
or
C-18
reverse
phase
materials
of
10
or
7µm
particle
diameter.
Elucidation
of
Metabolic
Structures
This
was
based
on
the
combined
information
obtained
from
instrumental
analysis,
retention
behavior
on
HPLC
columns,
results
of
selective
enzymatic
deconjugation
experiments
and
on
the
knowledge
of
the
various
biotransfor-
mation
reactions
described
in
the
literature.
Proton
(sometimes
also
Carbon
13)
nuclear
magnetic
resonance
spectra
were
recorded
on
90
or
250
MHz
spectrometers
(Bruker).
Mass
spectra
were
recorded
and
partly
interpreted
by
A.
Nikiforov
(University
of
Vienna/In-
stitute
for
Analytical
Chemistry)
using
a
MAT
311
instrument
and
either
fast
atom
bombardment,
field
desorption
or
electron
impact
techniques.
UV-spectra
were
recorded
with
the
mod.
1040A
diode
array
UV-detector
(Hewlett-Packard).
RESULTS
AND
DISCUSSION
The
major
routes
of
biotransformation
of
five
radiolabelled
allylamine
an-
timycotics
have
been
elucidated
in
up
to
seven
mammalian
species
including
man.
Summarized
in
Table
1
are
the
structures
of
these
compounds
and
the
positions
of
their
radiolabels,
together
with
the
species
so
far
investigated
with
respect
to
major
biotransformation
pathways
and/or
absorption,
distribution
and
excretion.
Absorption
Allylamines
1-5
(Figs.
3-7)
are
all
well
absorbed,
as
measured
by
the
amounts
of
total
radioactivity
excreted
in
urine
and
bile
(bile
in
rats
only)
and
by
comparison
with
data
obtained
after
i.v.
injection.
A
large
variability
in
the
degree
of
absorption
(20-100%)
was
seen
only
in
the
dog
after
oral
ad-
ministration.
This
phenomenon
was,
however,
most
probably
due
to
non-
optimal
galenic
formulation.
Comparison
of
the
degree
of
absorption
of
these
drugs
between
intact
and
bile
duct
cannulated
rats
indicates
the
im-
portance
of
a
normal
bile
flux
for
their
absorption.
BIOTRANSFORMATION
OF
ALLYLAMINES
485
intervals
after
dosing,
liver
was
invariably
found
to
contain
the
highest
levels.
With
increasing
lipophilicity
of
the
parent
drugs,
both
the
relative
and
the
absolute
amounts
of
radioactivity
in
adipose
tissue
increase.
In
the
case
of
terbinafine
and
compound
5
(Fig.
7),
radioactivity
levels
in
adipose
tissue
become
higher
than
those
in
liver
at
and
after
24
hr.
Radioactivity
levels
in
skin
also
increase
with
increasing
parent
drug
lipophilicity
and
are
also
higher
than
in
liver
at
later
time
points
after
oral
administration
of
com-
pound
5
(Fig.
7).
A
high
proportion
of
total
radioactivity
in
organs
and
tissues
is
made
up
of
parent
drug
and
of
still
highly
lipophilic
metabolites
(5).
As
will
be
shown
later,
radioactivity
in
plasma
is
primarily
due
to
the
presence
of
more
polar,
almost
antimycotically
inactive
metabolites
already
at
the
time
of
peak
plasma
levels
of
total
radioactivity,
which
are
normally
reached
between
two
and
eight
hr
after
oral
administration.
Elimination
Extensive
biotransformation
is
required
in
order
to
render
these
lipophilic
drugs
sufficiently
polar
for
subsequent
excretion.
This
is
clearly
demonstrated
by
the
fact
that
parent
drug
and
the
most
lipophilic
metabolites
found
in
the
tissues
are
hardly
found
in
the
blood
and
that
the
more
polar
metabolites
predominant
in
blood
are
not
predominant
in
the
excreta.
For
the
more
extensively
investigated
compounds
1,
3
and
5
(Figs.
3
,
5
and
7,
respectively)
biliary
excretion
clearly
dominates
in
rats
and
dogs,
where
80%
of
the
absorbed
dose
is
eliminated
via
this
route.
In
intact
rats,
10
(compounds
1
and
3)
to
30
(compound
5)
percent
of
the
metabolites
initially
eliminated
with
the
bile
undergo
enterohepatic
recycling
and
are
subsequently
excreted
with
urine.
In
guinea
pigs,
a
study
on
the
degree
of
absorption
and
routes
of
elimination
of
orally
administered
naftifine
in-
dicated
quantitative
absorption
and
a
one
to
one
ratio
of
renal
and
biliary
excretion.
In
rabbits
and
in
humans,
urine
is
the
main
route
of
excretion.
In
these
species,
the
extent
of
enterohepatic
recycling
is
yet
unknown.
For
all
compounds,
the
bulk
of
administered
radioactivity
is
excreted
within
two
days.
The
remainder
is
eliminated
slowly
and
was
clearly
cor-
related,
in
rats,
with
the
decrease
in
the
radioactivity
levels
in
adipose
tissue
and
in
the
skin.
Biotransformation
Routes
In
case
of
the
extensively
investigated
compounds
naftifine
1
(Fig.
3)
and
terbinafine
3
(Fig.
5)
and
also
of
87-469
5
(Fig.
7),
eighty
or
more
percent
of
the
radioactive
materials
in
these
samples
could
be
correlated
with
struc-
486
F.A.
BATTIG,
M.
NEFZGER
AND
G.
SCHULZ
turally
known
metabolites.
These
were
usually
isolated
from
urine,
and
oc-
casionally
from
bile,
in
the
most
appropriate
species.
The
metabolic
pattern
in
the
various
samples
were
analyzed
by
means
of
reverse
phase
HPLC
with
on-line
or
off-line
radioactivity
measurement.
Figure
1
shows
typical
on-line
radiochromatograms
of
terbinafine
in
plasma,
urine
and
bile
of
rats.
Figure
2
shows
a
typical
«synthetic»
radiochromatogram
resulting
from
off-line
radioactivity
measurement
of
a
plasma
sample
from
a
male
volunteer
who
had
received
an
oral
dose
of
radiolabelled
terbinafine.
In
the
subsequent
description,
routes,
by
which
approximately
5-10%
or
more
of
the
absorbed
dose
were
metabolized,
are
arbitrarily
designated
«major
routes»
and
all
others
«minor
routes».
OXIDATIVE
N-DEALKYLATION
Oxidative
N-dealkylation
is
one
of
the
major
biotransformation
routes
for
all
of
these
allylamine
antimycotics
and
oc-
curs
randomly
at
each
of
the
three
carbon
atoms
attached
to
the
nitrogen
atom.
N-DEMETHYLATION
All
investigated
compounds
are
tertiary
methylamines.
From
a
quantitative
point
of
view,
N-demethylation
is
the
most
important
N-dealkylation
route.
Demethylated
parent
drugs
are
frequently
detected
in
plasma,
but
have
so
far
not
been
found
in
the
excreta,
evidently
due
to
their
still
high
lipophilicity.
Most
of
the
formaldehyde,
which
is
the
other
primary
product
of
N-demethylation,
is
further
oxidized
to
formic
acid
and
finally
to
carbon
dioxide,
whereas
minor
fractions
of
formaldehyde
and
formic
acid
may
be
incorporated
into
the
endogenous
C-1
pool
(9).
N-DEALKYLATION
AT
THE
ALLYLIC
POSITION
The
primary
products
of
this
N-dealkylation
route
are
shown,
in
brackets,
in
the
biotransformation
schemes
illustrated
in
Figs.
3-7.
Since
no
primary
or
secondary
amine
metabolites
of
this
type
have
been
detected,
they
are
evidently
subjected
to
further
N-dealkylation.
The
bulk
of
the
allylic
aldehyde
primary
products
11,
24,
33
and
49
is
oxidized
to
the
carboxylic
acids
(e.g.,
metabolites
12
and
34).
Reduction
of
these
aldehyde
intermediates
to
alcohols
has
so
far
not
been
observed,
in
contrast
to
the
aromatic
aldehyde
intermediates
discussed
below.
So
far,
we
have
only
been
able
to
quantify
exactly
the
metabolites
of
the
allylic
chain
of
compounds
3
and
5,
which
carry
the
radiolabel
in
the
appropriate
position
(Table
1).
In
these
two
compounds,
it
seems
to
be
the
quantitatively
least
important
N-dealkylation
route.
BIOTRANSFORMATION
OF
ALLYLAMINES
487
N-DEAumAnoN
ALPHA
TO
THE
AROMATIC
RING
SYSTEM
The
primary
intermediates
of
this
N-dealkylation
route
are
also
shown
in
brackets,
in
the
schemes
illustrated
in
Figs.
3-7.
In
this
case,
small
amounts
of
amine-
type
metabolites
are
detectable,
e.g.,
metabolites
36
and
37
both
with
ter-
binafine
and
with
87-469.
The
bulk
of
the
aromatic
aldehyde
intermediates
is
oxidized
to
the
car-
boxylic
acid
metabolites
7
and
57,
and
a
small
fraction
is
reduced
to
the
alcohol
metabolites
8
and
58.
These
alcohols
are
normally
conjugated
and
excreted,
whereas
a
significant
portion
of
the
carboxylic
acids
is
excreted
in
the
unconjugated
state.
Since
these
acids
and
alcohols
plus
their
con-
jugates
are
almost
exclusively
eliminated
with
urine,
and
since
their
molar
extinction
coefficients
allow
for
sensitive
UV-detection,
they
are
the
prefer-
red
«marker
substances»
to
follow
the
biodegradation
of
unlabelled
allylamine
antimycotics
in
volunteers
and
test
animals.
This
N-dealkylation
route
does
not
only
apply
to
parent
drug
and
tert.
amine-type
metabolites,
but
also
to
the
secondary
and
even
primary
amine-
type
intermediates
resulting
from
the
other
two
N-dealkylation
routes.
It,
therefore,
is
a
very
important
biotransformation
pathway
for
allylamine
antimycotics.
ALIPHATIC
OXIDATION
The
products
resulting
from
aliphatic
oxidation
at
the
carbon
atoms
adjacent
to
nitrogen
have
been
discussed
in
the
previous
chapter.
Naftifine
1
does
not
contain
another
aliphatic
carbon
atom
(Table
1,
Fig.
3).
Whether
and
to
which
extent
methyl
groups
of
the
trimethylsilyl
moiety
of
compound
4
(Table
1,
Fig.
6)
are
oxidatively
attacked
is
unknown
for
the
reasons
discussed
in
the
section
of
this
paper
entitled,
«special
or
minor
biotransformation
pathways.»
The
allylic
chain
of
compound
2
(Fig.
4)
contains
a
n-butyl
group,
which
is
oxidatively
attacked
at
two
different
positions:
a)
The
terminal
methyl
group
is
hydroxylated
resulting
in
the
formation
of
a
primary
alcohol
group,
which
is
extensively
further
oxidized
to
the
carboxylic
acid
level.
This
is
concluded
from
the
fact
that
no
such
primary
alcohol
metabolites
or
conjugates
thereof
were
isolated
from
urine,
but
only
the
five
carboxylic
acid
metabolites
26
and
28-31.
b)
The
methylene
group
in
alpha
position
to
the
acetylene
function
is
also
hydroxylated
leading
to
metabolites
26
and
31.
Quantitatively,
oxidative
attack
at
the
terminal
methylene
group
seems
to
be
more
important.
Compounds
3
(Fig.
5)
and
5
(Fig.
7)
contain
a
tertiary
butyl
group
in
the
allylic
chain.
One
of
its
three
methyl
groups
is
readily
hydroxylated,
again
leading
to
formation
of
a
primary
alcohol
group
which,
however,
488
F.A.
BATTIG,
M.
NEFZGER
AND
G.
SCHULZ
is
not
to
the
same
extent
further
oxidized
to
the
carboxylic
acid
level
as
was
found
in
the
case
of
compound
2
(Fig.
4).
Three
alternative
pathways
of
further
biotransformation
can
be
deduced
from
the
structures
of
the
metabolites
shown
in
Figs.
5
and
7:
a)
Further
oxidation
to
the
carboxylic
acid
level
(metabolites
36, 37,
39,
40-42,
46, 47,
61
and
63);
b)
Combination
with
N-dealkylation
and/or
aromatic
oxidation
(metabolites
34,
35, 39,
44
and
45);
and
c)
Conjugation
and
excretion
(metabolites
43
and
62).
Quantitatively,
a)
is
most
important,
b)
also
occurs
to
a
considerable
ex-
tent,
while
c)
is
but
a
minor
route
for
this
primary
alcohol
type
metabolite.
AROMATIC
OXIDATION
Aromatic
oxidation
is
a
major
biotransformation
pathway
for
compounds
1-4.
Their
naphthalene
ring
system
is
oxidatively
attacked
in
alternative
positions
of
both
rings
to
yield
epoxide
intermediates.
These
are
evidently
excellent
substrates
for
epoxide
hydrolase(s),
since
on-
ly
the
corresponding
dihydrodiols
(metabolites
13,
14,
16
and
correspon-
ding
metabolites
of
compounds
2-4),
but
no
naphthols,
mercapturic
acids
or
other
products
have
so
far
been
identified.
In
contrast
to
the
arene
oxide
intermediates
of
the
naphthalene
ring
system
finally
leading
to
dihydrodiols,
the
major
products
of
aromatic
oxidation
in
the
phenyl
group
of
naftifine
1
are
phenol-type
metabolites
with
the
hydroxy
group
in
para
position
(metabolites
18-20
and
22).
These
are
nor-
mally
conjugated
and
directly
excreted.
In
a
preliminary
study
on
the
biological
fate
of
compound
5
in
rabbits,
no
products
of
aromatic
oxidation
have
been
detected
so
far,
although
most
of
the
major
metabolites
in
plasma
and
urine
have
been
identified.
This
indicates
higher
stability
of
the
3-chlorobenzothiophene
group
against
arene
oxide
formation,
as
compared
to
the
napthalene
ring
system
in
compounds
1-4.
CONJUGATION
REACTIONS
For
the
primary
alcohol-,
dihydrodiol-
and
phenol-type
metabolites,
glucuronidation
is
the
dominating
route
of
con-
jugation.
The
only
exception
to
this
is
the
dihydrodiol-type
metabolite
54
of
compound
4,
which
was
shown
to
be
a
sulfate
conjugate.
The
aromatic
carboxylic
acid
type
metabolites
(e.g.,
7)
are
excreted
either
unconjugated,
or
conjugated
to
roughly
equal
portions
with
glucuronic
acid
or
glycine.
The
aliphatic
carboxylic
acid
type
metabolites
(e.g.,
40
and
46)
were
normally
excreted
unconjugated.
N-Acetylation
was
found
to
occur
in
the
case
of
metabolite
37
(Figs.
5
and
7).
Here
the
corresponding
primary
amine
resulting
from
double
N-
dealkylation
of
the
allylic
group
of
compounds
3
and
5
is
the
substrate.
BIOTRANSFORMATION
OF
ALLYLAMINES
489
This
conjugation
reaction
was
found
to
occur
at
least
in
rabbits
and
rats.
The
situation
in
other
species
has
not
yet
been
fully
clarified.
A
similar
example
of
N-acetylation
of
a
primary
aliphatic
amine
metabolite
resulting
from
double
N-demethylation
of
the
tertiary
amine
drug
(
+
)-methadone
has
been
described
in
the
literature
(17).
Special
or
Minor
Biotransformation
Pathways
CLEAVAGE
OF
THE
ACETYLENIC
CARBON-SILICON
BOND
The
trimethylsilyl
group
of
compound
4
is
quantitatively
split
off
in
vivo
as
can
be
deduced
from
the
structure
of
metabolites
51-54
in
Figure
6.
The
exact
mechanism
of
this
enzymatic(?)
biodegradation
is,
at
present,
unknown.
REDUCTION
OF
THE
OLEFINIC
DOUBLE
BOND
As
part
of
the
overall
biotransformation
of
compounds
3
and
5,
the
olefinic
double
bond
of
metabolite
34
is
reduced
to
give
metabolite
35
(Figs.
5
and
7).
Since
this
bioreductive
step
has
not
been
observed
in
any
metabolites
with
the
allylic
group
still
attached
to
the
nitrogen
atom,
it
is
concluded
that
the
metabolical-
ly
introduced
carboxylic
group
adjacent
to
the
olefinic
double
bond
exerts
an
activating
effect
on
this
rather
unusual
biotransformation
reaction.
Rare
cases
of
such
bioreductions
have
recently
been
published
(6-8,
11).
ALDEHYDE
REDUCTION
Normally
less
than
10%
of
the
aldehyde
primary
products
resulting
from
the
various
N-dealkylation
routes
are
reduced
to
the
corresponding
alcohols
that
are
subsequently
conjugated
and
excreted.
Aldehyde
reduction,
thus,
seems
to
be
but
a
minor
pathway
in
the
biotransformation
of
compounds
1-5.
It
can,
however,
not
be
ruled
out
that
also
the
aldehyde
intermediates
formed
upon
further
oxidation
of
the
primary
alcohol
metabolites
of
compounds
3
and
5
to
the
carboxylic
acid
level
might
be
partly
reduced
back
to
the
alcohol
level.
OTHER
MINOR
REACTIONS
The
phenyl
group
of
naftifine
1
was
found
to
yield
small
amounts
of
phenol
metabolites
with
the
hydroxy
group
in
methaposition
(metabolite
21).
Trace
amounts
of
catechol-type
metabolites
were
also
found
(metabolite
19)
and
another
minor
metabolite
(metabolite
22)
points
to
additional
0-methylation
(1,
3).
ACKNOWLEDGEMENTS
The
animal
experiments
were
primarily
carried
out
by
K.
Kritzinger,
N.
Teherani
and
Ch.
Zima.
D.
Jobstmann
and
R.
Plot
isolated
and
purified
most
of
the
approximately
40
different
fully
identified
metabolites.
Together
with
B.
Rizovski
they
also
analyzed
most
of
the
metabolic
patterns.
T.
Gramanitsch
contributed
important
information
on
specific
structural
490
F.A.
BATTIG,
M.
NEFZGER
AND
G.
SCHULZ
CID
/ \
-
R
H
or
co
ni
ug
a
te
Fig
ure
3
Bio
tran
s
fo
rma
t
ion
sc
he
me
o
f
na
ft
ifine
(
1).
\ /
-z
\
/ \
\
/
8
O
/
/ \
\ / \
/
23
B
I
O
T
RANSF
O
R
M
ATIO
N
O
F
AL
L
YL
AM
INES
COOR
OR
H
4
CH
2
O
25
_J
OR
H
N
om/
COOK
26
I
R
=
H
or
coniugale
CHO
1
Nw-"'"'""N-COOR
OR
30
Figure
4
Biorransformation
scheme
of
85-533
al.
27
RO
29
I
28
''OR
L'Hc
24
+
I
H
)
<
COOR
e).,kCOOR
40.
RO
41
39
OR
4
OR
2
38
CH,0
)<
3
t
l
j <
COOR
tril
"...."
%,""
36
)(COOR
37
0
1
,Jc"
,
oR
OHC
-
ROOV
k.."
3
4
e)
C'OR
OR
ROOC'
"•'"
35
COOK
OR
0*
CHO
0*
*
32
tN)
ElI
IHDS
'0
CIN
V
1130
Z
AHN
'I
N
`9
11.
1.
Vk1
'V
*3
'
OR
43
RO
-
45
on
44
OR
1„.001:111
I
CCOR
R.
H
or
coniugale
46
RO
47
Figure
5
Biotransformation
scheme
of
terbinafine
(3).
4
COOR
OR
H
I
+
CH
2
O
50
H
51
H
N
NW
CHO
48
NW
''OR
OR
52
R.H
or
conjugate
53
RO
54
OR
Figure
6
Biotransformation
scheme
of
86-362
(4).
57
„irE
tl,
.,,
..„1/4
37cooR
o
)<COOR
36_
56
H
32
-
"‘"kb"
--
55
OHC
33
1
)OR
---
HOOV
4
k."
35
34
OR
1
CI
58
CI
s
+
CH
2
0
OR
,
59
CI
L
CI
CI
t
I
Nei
I
60
,
62
CI
CI
i
-COOK
COOR
COOK
CHO
61
63
CI
CI
F
.A
.
BATT
IG
,
M
.
NEFZGE
R
AND
G
.
SC
HULZ
H
or
conjugate
Figure
7
Biotranslormation
scheme
of
87.469
BIOTRANSFORMATION
OF
ALLYLAMINES
495
features
of
hitherto
unknown
metabolites
by
on-line
spectral
analysis
with
the
diode
array
UV-detector.
He
also
planned
and
supervised
the
experimen-
tal
work
of
L.
Dor
and
A.
Tuschil,
who
investigated
the
biotransforma-
tion
of
compound
5.
A.
Stuetz,
I.
Schuster
and
N.
Ryder
helped
in
prepar-
ing
this
manuscript.
We
also
wish
to
especially
thank
R.
Czok,
who
essen-
tially
planned
the
animal
and
clinical
studies,
for
constant
encouragement
of
our
work
and
for
many
fruitful
discussions
and
suggestions.
References
1.
Bakke,
O.M.
0-Methylation
of
simple
phenols
in
the
rat.
Acta
Pharmacol
Toxicol
1970;
28:
28-38.
2.
Battig,
F.A.,
Nefzger,
M.,
Czok,
R.
11.
SF-86-327:
Pharmacokinetics
and
biotransfor-
mation
of
the
14C-labelled
drug
in
laboratory
animals
and
man.
13th
Intl
Cong
Chemother
(August
28-September
2,
1983,
Vienna),
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12.
PS4.8/4-10.
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Glazko,
A.J.
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Grimus,
R.C.,
Schuster,
I.
The
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the
13.
lymphatic
transport
in
the
enteral
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naftifine
by
the
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1984;
14:
287-294.
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Grimus,
R.C.,
Schuster,
I.
SF
86-327:
Uptake,
distribution
and
metabolism
in
the
rat.
A
com-
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of
in
vitro
and
in
vivo
data.
13th
Intl
14.
Cong
Chemother
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1983,
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IS.
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Lindstrom,
T.D.,
Whitaker,
G.W.
Saturation
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A
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1984;
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Lindstrom,
T.D.,
Whitaker,
G.W.
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1984;
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Mashford,
P.M.,
Jones,
A.R.
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17.
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A
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Petranyi,
G.,
Ryder,
N.S.,
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A.
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New
class
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antifungal
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R.H.,
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T.A.,
Monis",
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from
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in
humans.
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F.,
Haberl,
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D.,
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G.,
Nefzger,
M.,
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R.,
Nikiforov,
A.
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nal-
One
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I.
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ler-
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in
liver
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In:
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Stuetz,
A.,
Georgopoulos,
A.,
Granitzer,
W.,
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G.,
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D.
Synthesis
and
structure-activity
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of
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related
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J
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A.,
Petranyi,
G.
Synthesis
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an-
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of
(E)-N-(6,6-dimethy1-2-
hepten-4-yny1)-N-methyl-1-naphthalenemetha-
namine
(SF
86-327)
and
related
allylamine
derivatives
with
enhanced
oral
activity.
J
Med
Chem
1984;
27:
1539.1543.
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A.
Allylamines
-
a
new
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of
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in
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R.E.
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