Development of Patch and Spray Formulations for
Enhancing Topical Delivery of Sinomenine Hydrochloride

XINRU LI,

1

XIAOYAN LI,

1

YANXIA ZHOU,

1

YAN LIU,

1

MING GUO,

2

QINGFEN ZHU,

2

YUANCHAO XIE,

2

ZHIYUN FAN

2

1

Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China

2

Shandong Institute for Drug Control, Jinan 250012, China

Received 7 December 2008; accepted 16 August 2009

Published online 22 September 2009 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jps.21947

ABSTRACT: The purpose of this work was to investigate feasibility of a promising
topical drug delivery system (TDDS) for sinomenine hydrochloride (SMH), extracted
from the Chinese medicinal plant sinomenine acutum and currently used for the
treatment of rheumatoid arthritis. It was found that SMH was a weak base (p

K

a

,

7.98

0.04) with pH-dependent solubility and partition coefficient. The result of in vitro

permeation studies demonstrated that the permeation enhancer azone was the most
effective. In contrast, spray had higher accumulative permeated amounts of SMH than
patch, but permeated duration of spray was shorter than that of patch. The efficacy on
Freund’s complete adjuvant-induced arthritis suggested that there was near arthritis
index for SMH spray with medium dose (i.e., 15 mg/rat) and oral solution at a dose of
12 mg/rat, indicating that topical SMH delivery system could achieve the similar anti-
inflammatory efficacy with oral administration. Pharmacokinetic parameters including
C

max

and AUC for both topical preparations were lower than those for oral preparation,

which hinted that systemic side effect could be ignored. Therefore, the spray and patch
were promising formulations for successful topical delivery of SMH through the skin
instead of oral administration with side effects.

ß

2009 Wiley-Liss, Inc. and the American

Pharmacists Association J Pharm Sci 99:1790–1799, 2010

Keywords:

sinomenine hydrochloride; percutaneous; pharmacokinetics; log

P; spray;

patch; pharmacodynamics; physicochemical properties

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic auto-
immune disease characterized by inflammation of
the joints, with proliferation of the synovium and
progressive erosion of cartilage and bone. Extra-
articular immunologic abnormalities may extend
to involve other organ systems as well.

1

It can

result in significant pain, fatigue, disability,

functional loss, and enormous psychological and
social expense.

2–5

Topical drug delivery systems (TDDS), in com-

parison to conventional pharmaceutical dosage
forms such as oral preparation and injection, have
many advantages including improving systemic
bioavailability of active pharmaceutical ingre-
dients, avoiding hepatic first pass metabolism,
fewer administration frequency, longer duration
of therapeutic action, reduction of side effects,
steady drug delivery profile, excellent patient
compliance and so on.

6,7

Besides, TDDS were

especially fit for anti-inflammation, abirritation,
and soft tissue injuries such as myositis, tendi-
nitis, synovitis, etc., because of avoiding side

Correspondence to: Yan Liu (Telephone: [phone];

Fax: [phone]; E-mail: [e-mail])

Journal of Pharmaceutical Sciences, Vol. 99, 1790–1799 (2010)
ß

2009 Wiley-Liss, Inc. and the American Pharmacists Association

1790

JOURNAL OF PHARMACEUTICAL SCIENCES, VOL. 99, NO. 4, APRIL 2010

effects of gastrointestinal tract (GI) after adminis-
trated systemically. The common dosage forms
of TDDS comprise patch, topical solution, gel,
ointment, and so on.

Sinomenine is extracted from the Chinese

medicinal plant

sinomenine acutum. Chemically,

sinomenine hydrochloride (SMH) is 7,8-didehy-
dro- 4-hydroxy-3,7-dimethoxy-17-methyl-(9a,13a,
14a)-morphinan-6-one (Fig. 1) which has a
molecular weight of 401.89. As a potent nonster-
oidal

anti-inflammatory

drug

(NSAID)

and

immunosuppressive agent, SMH has a wide
range of actions including anti-inflammatory,

8

anti-rheumatic,

9

analgesic,

10

immunosuppressive

effects,

11–14

and protection against hepatitis

induced by endotoxin.

15

However, like other

NSAIDs, SMH may cause gastric intestine and
kidney damage, and besides may affect liver and
heart after long-term treatment,

16–20

which

makes the topical dosage forms of SMH an
attractive alternative delivery route to avoid the
oral side effects and provide relatively consistent
drug levels at the application site for prolonged
periods. Preliminary studies about TDDS of SMH
including patch, microemulsion, and liposome
were previously reported.

21–24

The results of

in vitro permeation experiments indicated that
SMH might permeate rat’s skin successfully.
However, there were no

in vivo evaluation reports

to show that these TDDS of SMH were effective
in vivo. Furthermore, differences of permeated
capacity between different TDDS of SMH were not
investigated in detail. Therefore, it is necessary to
develop a satisfied TDDS for SMH via compre-
hensive consideration and evaluation.

The aim of this study was to prepare two TDDS

such as patch and spray. First of all, it was
very necessary for above goal that physicochemi-
cal parameters of SMH were determined. The

quality, high therapeutic efficacy, and safety via
detailed studies included

in vitro permeation,

pharmacokinetics, pharmacological activity in
rats, and topical skin irritation were studied to
assess their potential for TDDS.

MATERIALS AND METHODS

Materials

SMH was obtained from Xi’an Lijun Pharmaceu-
tical Co., Ltd (Xi’an; China). Eudragit

1

E PO was

a gift from Degussa Chemical (Shanghai, China);
diethyl sebacate, succinic acid, azone (1-dodecyl-
hexahydro-2H-azepin-2-one) were obtained from
Sigma (Beijing, China). All other adjunctive
materials and reagents with analytical grade
were purchased from commercial sources.

Healthy male Wistar rats and male Sprague–

Dawley rats were supplied by the Experimental
Animal Breading Center of Shandong University.
Healthy male New Zealand rabbits were obtained
from institute of prologue, Shandong academy of
agricultural science. All animal experiments were
conducted in accordance with the rules set forth in
the NHI Guide for the Care and Use of Laboratory
Animals, and were approved by the ethics
committee of Peking University Health Science
Center.

Methods

Determination of Physicochemical Parameters
for SMH

Ionization Constant. Ionization constant (

K

a

)

of SMH was determined by potentiometry. Aqu-
eous solutions of SMH were prepared over a
concentration interval from 2.0 to 12 mmol/L in
triplicate, which was titrated by 0.1 mol/L purified
carbonate-free sodium hydroxide solution at
32

18C. The titration volume of sodium hydro-

xide and the pH value were recorded, and p

K

a

was

calculated.

Solubility. To determine the saturation solubi-
lity of SMH, excess drug was added to normal
saline in iodine flask. The mixtures were shaken
at 32

18C for more than 48 h, and then filtrated

with a 0.22 mm pore-sized filtration membrane
(Millex-GV, Millipore Co., Bedford, MA). Filtrates
were diluted and analyzed by HPLC. The experi-
ments were done in triplicate.

Figure 1. Chemical structure of SMH.

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DEVELOPMENT OF PATCH AND SPRAY FORMULATIONS

1791

Partition Coefficient. Octanol/water partition
coefficient (

P) of SMH was determined by shake-

flask method that was based on thorough mixing
of the two phases to reach the equilibrium.

25,26

Stock solutions of SMH were made in aqueous
solution with pH of 2, 3, 4, 5, 6, 7, 8, 9, 10 adjusted
with hydrochloride solution or sodium hydroxide
solution, and presaturated with the analytic
grade

n-octanol. Ten milliliters of stock solutions

were merged with 10 mL of

n-octanol phase

presaturated with water, and the phases of the
solvent system were mutually saturated by
shaking for 24 h on a mechanical shaker at the
target temperature of 328C. After centrifugation
at 4000 rpm for 20 min, the SMH concentrations
in each phase were determined by HPLC. Three
independent measurements were conducted with
all solutions. Apparent partition coefficient

P

app

and

P were calculated according to the litera-

ture.

27

Preparation of Topical SMH Delivery Systems

Preparation of SMH Spray. SMH spray was
prepared by dissolving SMH in water at concen-
trations of 1–5% (w/v), and then appropriate
stabilization agent was added. The spray was
sprayed with a mechanical pump which allowed
one to dispense a prefixed amount, corresponding
to the desired dose. To enhance permeation of
drug, permeation enhancers such as azone, oleic
acid, and alcohol, were used.

Preparation of SMH Patch. The polymeric
solution was prepared by dissolving 70% (w/w)
of Eudragit

1

E PO, along with 24% (w/w) of

succinic acid (crosslinker), and 6% (w/w) of diethyl
sebacate (plasticiser) based on total excipient
weight in alcohol/water (1:1, v/v) mixtures. A
certain amount of SMH and 5% (w/v) of azone
(penetration enhancer) were added. The solution
was spread on paper coated by polyester as release
liner (which could be removed before application
of the patch on the skin). The solvents were
allowed to evaporate at 608C for 2 h. Aluminium
coated by polyester foil was used as backing foil.
The patches were cut into a rectangular shape
with the size of 10 cm

6 cm and stored in air tight

container at ambient conditions prior to use.

In Vitro Permeation Studies

Franz-type diffusion cells with a permeation
surface area of 1.76 cm

2

were used to study the

permeability of SMH. Skin samples were obtained
from male Wistar rats weighing 180–220 g. After
hair was shaven using a mechanical hair clipper,
without damaging skin, a 3 cm

3 cm patch of

skin was excised from the abdominal region of
each sacrificed rat and the adhering fat and other
visceral tissue was removed carefully. The excised
rat skin was stored at

208C and used within

1 week after harvesting. They were then placed
between the donor and receptor compartments of
the cells, with the dermal side in direct contact
with the receptor medium. Approximately 13 mL
of phosphate buffer (PBS, pH 7.4) was placed in
the receptor compartment. The temperature was
maintained at 32

0.58C using a thermostatic

water bath, and the rotation speed was set at
100 rpm during the experiment. The donor
compartment contained 1.5 mL of solution of
spray or 1 cm

2

of patch. One milliliter of the

receptor medium were withdrawn and replaced
with an equal volume of freshly prepared medium
at predetermined time intervals. The amounts of
SMH permeated through skin into the receptor
medium were determined using a validated
HPLC at the wavelength of 265 nm, 20 mL of
receptor medium was injected into HPLC system
(Shimadzu, Japan) equipped with a UV detector
and ODS C

18

column at room temperature.

The mobile phase was methanol/0.1% (v/v) ethyl
diamine solution (1:2, v/v) adjusted to pH 7.0 with
hydrochloride solution. The flow rate of the mobile
phase was 0.8 mL/min. Three replicates of each
experiment were performed. The accumulative
amount (mg/cm

2

) of SMH permeated through the

rat’s skin was plotted as a function of time (

T, h).

Freund’s Complete Adjuvant-Induced Arthritis
in Rats

Male Wistar rats weighing about 200 g were
randomly classified into ten groups (

n

¼ 10) to

perform the following experiment. Saline was
administered topically in model group 1. The
animals were applied to the 15 cm

2

skin area with

blank patch in model group 2. Intra-gastric
perfusion of prednisone at a dose of 6 mg/kg
(1.5 mg/mL, 4 mL/kg) was the positive group one
and another positive group was intra-gastric
perfusion of SMH solution at a dose of 6 mg/kg
(15 mg/mL, 0.4 mL/kg). There were two sets of test
groups in total. One was administrated with
topical SMH spray at doses of 5, 15, 25 mg/rat (1%,
3%, and 5%, w/v, i.e., 0.5 mL/rat) and the other

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DOI 10.1002/jps

1792

LI ET AL.

was administrated to the same area at doses of
1.83, 3.0, 3.69 mg/rat of topical SMH patch. In
above groups animals were administrated once
per day for 22 successive days. Each animal was
given endermic injection of 0.1 mL of Freund’s
complete adjuvant [FCA, 2:1 liquid paraffin/
lanolin were heated to melt at 708C. After
autoclaving, the fusion was mixed with Bacille
Calmette Guerin (1 mL:10 mg) and emulsified
thoroughly] into the site of the right hind digiti
pedis after 1 h of first delivery. Ankle circumfer-
ence was measured for both paws with a flexible
strip at different intervals. The swelling degree
was calculated by the difference of ankle circum-
ference of the right hind digiti pedis in each rat
between different time after administration and
0 day. Arthritis index was calculated by summing
the scores recorded for each paw according to
previous report.

28

Pharmacokinetics Evaluation

Eighteen Male Sprague–Dawley rats weighing
150–180 g were enrolled in the study, and were
randomly separated into three groups. One group
was administered orally with 0.3 mL of 3% (w/v)
SMH aqueous solution. The other two groups were
given at the same dose by topical preparations
including 3% (w/v) SMH sprays and 0.2 mg/cm

2

SMH patches with a 4.5 cm

2

area, respectively.

The topical preparations were administrated on
the rat’s back. No food was allowed 12 h before
experiments to be finished. At each time point of
0.25, 0.5, 0.75, 1, 2, 4, 6, 9, 12, 18, 24 h, the rats
were anesthetized with ether, and 0.8 mL of total
blood was withdrawn from retroorbital plexus.
The collected blood samples were immediately
transferred into polypropylene tubes containing a
small amount of heparin sodium and centrifuged
at 7,000 rpm for 10 min to obtain plasma.
The plasma was stored at

208C before HPLC

analysis.

Four hundred fifty microliters of the plasma

were mixed with 25 mL of 20 mg/mL chloramphe-
nicol solution as internal standard and 3 mL of
ether as extraction solvent. The mixture was
shaken for 3 min and the extracts were centri-
fuged at 4,000 rpm for 5 min. After evaporation
under a stream of nitrogen at 408C, residues were
reconstituted in 100 mL of mobile phase. The
concentration of SMH in plasma was measured by
HPLC at the wavelength of 265 nm. Twenty
microliters of aliquot was injected into the HPLC

system (Agilent Co., Wilmington, DE) equipped
with a UV detector and ODS C

18

column at 358C.

The mobile phase was acetonitrile/0.01 mol/L
sodium phosphate monobasic solution/

N,N,N

0

,

N

0

-

tetramethlenediamine (46:54:0.22,v/v) adjusted
to pH 6.9 with phosphoric acid. The flow rate of
the mobile phase was 0.8 mL/min. The pharma-
cokinetic parameters were obtained using the
noncompartment method of analysis. The area
under the plasma concentration versus time curve
(AUC) was calculated by trapezoidal rule. Time to
reach the maximum drug plasma concentration
(

T

max

) and the peak plasma concentration (

C

max

)

were obtained by direct observation of the
concentration–time plots. The relative bioavail-
ability of topical preparations such as spray and
patch, compared to oral preparation (oral solu-
tion), was calculated according to the formula:

Relative bioavailability

ð%Þ ¼

½AUC

T

100%

½AUC

R

(1)

where [AUC]

T

is the area under the curve of

topical preparations including spray or patch and
[AUC]

R

is the area under the curve of SMH oral

solution.

Assessment of Skin Irritation

Six New Zealand rabbits weighing 2.1–2.6 kg were
divided into two groups randomly with three in
each group, including integrated skin group and
dilapidation group in which skin was lacerated
with 16

#

pinhead. A 60 cm

2

area of fur on the back

was depilated with 8% (w/v) sodium sulfide
solution. The SMH patches at a dose of 12 mg
and blank patches were applied to the above group
animals, once per day. After 23 h of per delivery,
patches were removed. After 1 h of removal, the
skin was observed whether there were erythema
(redness) and oedema (swelling) at the site of
delivery or not. The patches mentioned above at
the same dose were administrated once more.
After 24 h patches were removed and residue was
purged of by warm water. The skin was observed
whether there were erythema (redness) and
oedema (swelling) after 1, 24, 48, and 72 h.
Another six New Zealand rabbits were used
similarly for SMH spray. The experiment method
was similar to that of patch described above except
dose schedule in which SMH spray at a dose of
30 mg/rabbit (3%, w/v, i.e., 1 mL/rabbit) and saline
were applied as test group and model group,
respectively.

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DEVELOPMENT OF PATCH AND SPRAY FORMULATIONS

1793

The site of patch/spray application was visually

examined for cutaneous irritation including
erythema and oedema. The scoring was recorded
according to the method used by Vlasses et al.

29

Statistical Analysis

Results were expressed as the means

SD.

Statistical differences were determined by Stu-
dent’s

t-test. The level of significance was taken as

p < 0.05.

RESULTS AND DISCUSSION

Physicochemical Properties

It is well known that a drug with the lipophilic
free acid or free base form has higher skin
permeability than that with the corresponding
hydrophilic salt form. Therefore, physicochemical
properties such as the diffusion behavior of the
drug molecule are the most important factors
influencing prescription and technology study
when investigating the feasibility of a topical
delivery system for a drug.

The

determination

of

ionization

constant

declared that SMH was a weak base with p

K

a

of

7.98

0.04. The degree of dissociation increased

with the increase of acidity of the solution owing
to protonation of tertiary amine group in drug
molecule (Fig. 1), which purported that water
solubility increased with the decrease of pH of
solution for SMH with alkaloid character.

The partition coefficient,

P, was defined as the

ratio of the concentration of the compound in two
immiscible liquid phases such as

n-octanol and

water. As shown in Figure 2a, with an increase
in pH of aqueous solution, concentration of SMH
in aqueous solution decreased, but concentration
of SMH in

n-octanol increased. Therefore, appar-

ent partition coefficient (

P

app

) increased gradually

(Fig. 2b), which was similar to other weak base
compounds such as benztropine and some local
anesthetic such as lidocaine, procaine, dibucaine,
and so on.

30–32

In term of Henderson–Hasselbalch

equation:

1

P

app

¼

1

P

þ

½H

þ

K

a

P

(2)

P

obtained

from

reciprocal

of

intercept,

was 22.22

0.36. For practical purposes, the

logarithm of the partition coefficient has been
widely used for predicting some physicochemical
properties such as membrane transport and water
solubility. By comparison, log

P (1.34) was slightly

lower than the specified scope, that is, 2–3, which
was considered to be optimal for a drug to
permeate through the skin.

33,34

The possible

reason was that SMH in molecule form had
considerably higher water solubility (10.5

1.8 mg/mL, Tab. 1), and moreover, salt effect of
all sorts of ion in the aqueous solution on
increasing water solubility of SMH should not
be ignored. Of course, relative high apparent
partition coefficient was acquired by adjusting
appropriate pH of the solution in order to increase
the permeation ability of drug.

The solubility of SMH in water and ethanol

were 118.8

4.2 and 11.4 1.1 mg/mL, respec-

tively, which demonstrated that SMH dissolved
easily in water or ethanol. The results were
consistent with solubility parameter (d

T

) calcu-

lated by the method from the literature.

35

The

solubility parameter of SMH (24.42 Mpa

1/2

) was

Figure 2. Effect of pH on (a) SMH concentrations in
aqueous phase (black diamonds) and

n-octanol phase

(open squares) and (b) apparent partition coefficients of
SMH.

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1794

LI ET AL.

close to that of ethanol (25.93 Mpa

1/2

), which

hinted that ethanol could be used as a solvent or
adjuvant for TDDS for SMH.

In summary, SMH had a potential of permeat-

ing through the skin to the target, however, some
additives such as permeation enhancer should be
used in order to achieve the best permeation.

In Vitro Permeation Studies

The plots of the accumulative amounts of drug
permeated through rat skin as a function of
time were shown for SMH spray with different
permeation enhancer in Figure 3a. The data
revealed that the permeated amount of SMH in
water was 0.5 mg/cm

2

at 12 h, which indicated

that SMH had an excellent permeated capability.
The result accorded with the prediction in term of
physicochemical parameters of SMH as described
in above section. Incorporation of 80% (v/v)
alcohol led to a remarkable increase in permea-
tion, and the accumulative amounts (0.663

0.036 mg/cm

2

) were higher than those in water

(0.497

0.039 mg/cm

2

) at 12 h (

p < 0.01), which

was attributed that lower molecular weight
alkanols such as alcohol were thought to act as
solvents enhancing the solubility of drugs in the
matrix of the stratum corneum.

36

Furthermore,

disruption of the stratum corneum integrity
through extraction of biochemicals by the more
hydrophobic alcohols also contributed to enhance
mass transfer through the tissue.

37

Incorporation of azone or oleic acid as permea-

tion enhancers into the spray formulation based
on 80% alcohol solution enhanced the delivery of
SMH through the rat’s skin, and the accumulative
permeated

amounts

of

SMH

were

0.700

0.027 mg/cm

2

and

0.668

0.040 mg/cm

2

after

12 h, respectively. Among the formulations exam-
ined, azone had the highest enhancing effect on
the permeation rate for SMH through the skin,
followed by oleic acid and alcohol. There were

remarkable differences for skin permeation-
enhancing effect between 80% alcohol with 1%
azone and 80% alcohol with 4% oleic acid
(

p < 0.05). As a result, the formulation containing

80% alcohol with 1% azone was selected for SMH
spray.

Similarly, addition of azone in patch also

promoted permeation of drug through skin in
rat. As shown in Figure 3b, with the increase of
azone concentration from 1% to 5% (w/v), accu-
mulative permeated amount of drug increased,
but decreased when azone concentration changed
from 5% to 10% (w/v), indicating that there existed

Table 1. Physicochemical Properties of SMH

Properties

Results

p

K

a

7.98

0.04

P

22.22

0.36

Water solubility (mg/mL)

118.8

4.2

Nonionic solubility (mg/mL)

10.5

1.8

Alcohol solubility (mg/mL)

11.4

1.1

Solubility parameter (MPa

1/2

)

24.42

Figure 3.

Cumulative precutaneous amount versus

time profiles of (a) SMH sprays and (b) SMH patches
in vitro (n

¼ 3). The solvents were water (black dia-

monds); 80% alcohol (open squares); 80% alcohol with
1% azone (black circles); and 80% alcohol with 4% oleic
acid (open diamonds). The concentration of azone was
1% azone (open diamonds); 2% azone (open squares);
5% azone (black triangles); 10% azone (multiplication
sign).

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DEVELOPMENT OF PATCH AND SPRAY FORMULATIONS

1795

optimum concentration for azone to achieve the
best permeation-enhancing effect. Therefore, the
optimized patch formulation contained 5% azone.
In addition, it was shown from Figure 3 that
accumulative permeated amount of drug reached
almost maximum platform at 6 h for SMH spray,
but increased constantly till 24 h for SMH
patch, which resulted from consecutive release
of SMH from patch because patch matrix impeded
the release of drug. It was concluded that SMH
patch showed clear characteristic of sustained
release.

Freund’s Complete Adjuvant-Induced
Arthritis in Rats

Freund’s adjuvant-induced arthritis was widely
used as a model of inflammation in rats. Injection
of FCA into rats resulted in some pathological
features such as lassitude, activity-lessening,
response torpor, forced foot, arthritis nodule in
trail, nasal part tumefaction, etc. The results
showed that the swelling degree of rats adminis-
tered two SMH formulations was lower than that
of the respective model groups as shown in
Figure 4, respectively, and furthermore, the
pathological symptom was alleviated as compared
with the model group. Similarly, arthritis index of
two SMH formulations also decreased (

p < 0.05)

as compared with the model group described in
Table 2. In addition, it could also be seen that
there was relative relationship between the dose
of SMH formulations and inhibitory effect, that is,
arthritis index. Therefore, topical delivery of
SMH spray and patch could inhibit effect of
FCA-induced primary foot swelling and secondary
arthritis.

Arthritis index of positive group (prednisone,

6 mg/kg) was close to that of SMH spray with high
dose, which demonstrated that the pharmacolo-
gical action of SMH was as better as prednisone.
However, the disadvantage of prednisone, the
same as those of steroidal hormone medicine was
the rebounding phenomena, inducing palindro-
mia and aggravation of protopathy commonly
presented after topping medication. And besides,
long-term taking the drug probably induced
syndrome of hyperfunctioning, duodenal ulcer,
asept necr fem head, etc.

38

In conclusion, TDDS of

SMH would be a prospective delivery manner for
anti-inflammation thereby substituted hormone
therapy.

Moreover, it was found that arthritis index of

SMH spray (medium dose, i.e., 15 mg/rat) was
similar to that of SMH through oral delivery
(12 mg/rat) (

p > 0.05) (Tab. 2), indicating that the

inhibition effect of 3% (w/v) SMH spray was close
to that of oral route which has been used in
clinic in China for many years and caused
some potential side effects.

19,20

On the basis of

these results, the finding that TDDS was
more suitable administration style for SMH as
compared with oral delivery could have important
clinical implications.

Figure 4. Mean swelling degree of (a) SMH sprays
and (b) SMH patches at different time.

p < 0.05 versus

model group;

p < 0.01 versus model group. Key: model

group—open diamonds; oral group—open squares; test
group (low dose)—open triangles; test group (medium
dose)—multiplication sign; test group (high dose)—
black circles; positive group—black diamonds.

Table 2. Arthritis Index of SMH Formulations

Spray

Patch

Model group

5.8

1.7

5.8

0.9

Test group (low dose)

4.7

1.8

5.2

0.8

Test group (medium dose)

4.0

2.4

a

4.5

1.4

a

Test group (high dose)

3.0

1.9

b

4.3

1.3

a

Oral group

3.9

2.4

Positive group

3.1

1.2

a

p < 0.05 versus model group.

b

p < 0.001 versus model group.

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By comparison, there was no significant dif-

ference in arthritis index between SMH spray (low
dose, i.e., 5 mg/rat) and SMH patch (medium dose,
i.e., 3 mg/rat) (

p > 0.05). This might attribute to

the consecutive release of drug from patch matrix
and the permeated drug concentrated in inflam-
mation focus. Thus, it was clear that pharmaco-
dynamic effect was taken efficiently for SMH
patch with nearly equivalent dose. In brief, it was
concluded that two formulations of SMH were of
noticeable anti-inflammatory activity and the
patch exhibited better efficacy at the lower dose.

Pharmacokinetic Profiles

Figure 5 shows the average concentration–time
profiles for SMH formulations after oral and
topical administration in rats. The

T

max

and

C

max

of

oral

administration

were

45 min

and 5.73 mg/mL (Tab. 3), respectively, which
indicated that SMH was adsorbed easily by oral
administration. In order to maintain the steady
drug plasma concentration, it was necessary to
delivery drug twice to thrice a day because of short
half life (

t

1/2

¼ 1.49 h). As compared, drug concen-

tration in rat plasma

C

max

and AUC of both topical

fomulations for SMH were obviously lower than
those of oral administration, and the relative
bioavailability (

F) of spray was only 28.6%.

For spray, from start to 2 h after topical adminis-
tration, only a little SMH was absorbed into
systemic circulation, and then drug concentration
decreased quickly owing to clearing and metabo-
lism action. For patch, little SMH was detected
in

plasma

throughout

the

pharmacokinetic

experiments (Fig. 5).

In addition, there was no relationship between

drug concentration in plasma and pharmaco-
logical effect. The reason could be that more
permeated SMH through the skin got to focus of
inflammation, and meanwhile only small amounts
of drug went into systemic circulation, which
confirmed the advantages of TDDS for SMH used
for topical treatment. The result was consistent
with the pharmacodynamic assessment, that is,
the patch exhibited the same anti-inflammatory
efficacy under the lower dose compared with the
spray. Furthermore, the systemic toxicity and side
effects of the topical formulations of SMH would
be neglected in comparison to oral preparation
(Fig. 5). Indeed, more detailed work is stilled
need for drug accumulation and concentration
variation with time in focus.

Skin Irritation

Usually, irritation potential of drugs seems to be
directly related to the concentration and contact
period of the irritant at the skin surface.

39,40

The

results of skin irritation in rabbits showed that for
both SMH spray and patch preparations no
irritation symptoms such as erythema (redness)
and oedema (swelling) was observed within 72 h
after administration and all the score were zero
(data not shown). The other symptoms about
pigmentation, bleeding point and pachulosis did
not appear either. It was concluded that the
irritation was not triggered off for the two
preparations with high concentration of SMH

Figure 5. Plasma

concentration–time

profiles

of

SMH following the topical application of both SMH
spray (open squares) and patch (open triangles), and
the oral application (black diamonds) to rats at a dose of
9 mg. Each time point represents means

SD (n ¼ 6).

Table 3. Pharmacokinetic Parameters of SMH Formulations According to Noncompartment Analysis Method

Formulation

T

max

(h)

C

max

(mg/mL)

t

1/2

(h)

AUC

0–24

(h mg/mL)

F (%)

Oral

0.75

5.73

2.10

1.49

0.48

11.25

3.41

100.0

Spray

1.0

1.11

0.38

2.64

1.60

3.22

0.95

28.6

Patch

0.75

0.34

0.52

—

a

0.09

0.13

<1.0

a

It was obtained impossibly because of ultra-low drug plasma concentration for patch.

DOI 10.1002/jps

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DEVELOPMENT OF PATCH AND SPRAY FORMULATIONS

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and the additives such as alcohol, Eudragit

1

E

PO, diethyl sebacate, succinic acid, azone, and so
on, even though drug concentration and rate of
permeation were considerably high. In conclusion,
SMH spray and patch were safe for skin in rabbit
and they were all well tolerated by the subjects.

CONCLUSION

The TDDS including spray and patch were
successfully developed on the basis of the physi-
cochemical study for SMH. It was proved that both
spray and patch displayed a favorable pharma-
cokinetics and pharmacodynamics in rats com-
pared with the oral preparation and no irritation
was observed in rabbits. What’s more, the patch
appeared to release sustainedly and exhibited the
same anti-inflammatory efficacy at the lower dose
compared with the spray. In conclusion, the two
TDDS offered a promising route for SMH that
bypassed the GI and might be a more convenient,
efficacious, safe, and noninvasive means espe-
cially for long-term use and arthritic patient with
GI illness.

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