Pharmacology & Pharmacy, 2011, 2, 159-163
doi:10.4236/pp.2011.23022 Published Online July 2011 (
Copyright © 2011 SciRes. PP
Determination of Capsaicin Induced Increase in
Dermal Blood Flow Using Laser Doppler
Flowmetry Technique
Sunil Kumar Reddy Khambam, Madireddy Umamaheshwar Rao Naidu*, Pingali Usha Rani,
Takallapalli Rame sh Kumar Rao
ICMR Advance Centre for Clinical Pharmacodynamics, Departments of Clinical Pharmacology & Therapeutics, Nizam’s Institute of
Medical Sciences, Panjagutta, Hyderabad, India.
Email: *
Received April 28th, 2011; revised May 20th, 2011; accepted June 30th, 2011.
In the present study, we evaluated laser Doppler flowmetry technique using LDF100C (Biopac systems) by determining
blood flow changes following acute application of capsaicin on 12 healthy human subjects. Capsaicin applied locally
(topical application) at a dose of 0.075% produced significant increase in mean dermal blood flow from 31.4 ± 3.1
Blood Perfusion Units (BPU) to 115. 7 ± 24.6 Blood Perfusion Units (BPU) after 30 minutes, also there was significan t
difference in dermal blood flow chan ge between placebo (32.1 ± 2.7 BPU) and capsaicin (115.7 ± 24.6 BPU) applica-
tion. Capsaicin applica tion produced significant pe rcentage change in dermal blood flow by 291.0 ± 85.3% fr om base-
line, while the change was insign ificant with pla cebo (13.2 ± 7.4%). Therefore , it is suggested that this technique which
is technically sound, non-invasive and inexpensive can be adopted in various fields of research to determine blood flow
changes and this technique ca n also be utilized to determine the antagonists of the mediato rs involved in ca psaicin in-
duced vasodilatation.
Keywords: Pharmacodynamics, Neurogenic Inflammation, Capsaicin
1. Introduction
Laser Doppler Flowmetry (LDF) is an established and
reliable method for measurement of blood perfusion in
microvascular research. Laser Doppler signals from the
tissue are recorded in BPU (Blood Perfusion Units)
which is a relative units scale defined using a carefully
controlled motility standard comprising a suspension of
latex spheres undergoing Brownian motion. The LDF
technique (Figure 1) offers substantial advantages over
other methods in the measurement of microvascular
blood perfusion. This technique provides promise and
opportunity to adapt the methodology in various fields of
research for example in cerebral monitoring (stroke, in-
jury ), transplantation surgery (skin grafts, free flaps ),
vital organ monitoring (organ viability), tumor vascular
research (angiogenesis) and peripheral vascular research
(diabetes). Studies have shown th at it is both highly sen-
sitive and responsive to local blood perfusion and is also
versatile and easy to use for continuo us monito ring [1,2].
Capsaicin, the pungent ingredient in a wide variety of
hot peppers, has been used extensively in human pain
models to induce experimental pain [3-6]. Application of
capsaicin to the skin activates the transient receptor po-
tential vanilloid type 1 receptor (TRPV1), producing neu-
rogenic inflammation and vasodilation [7,9-12]. Most
evidence indicates that the release of calcitonin gene-
related peptide (CGRP) is a major initiator of this re-
sponse [13,8]. Other putative bioactive mediators are
substance P (SP), neurokinin (NK) A, somatostatin, ni-
tric oxide (NO), histamine and prostaglandins, but their
role in capsaicin-induced neurogenic inflammation in the
normal human skin is not well established [14-18].
The aim of the study was to determine microvascular
changes following acute application of capsaicin using
laser Doppler flowmetry Technique.
2. Materials and Methods
Twelve healthy, male subjects between 24 and 32 years
old were enrolled. Mean ±SD (range) for age, weight,
height and Body Mass Index (BMI) were given in Table
160 Determination of Capsaicin Induced Increase in Dermal Blood Flow Using Laser Doppler Flowmetry Technique
Table 1. Showing demographic char acteristics of study par-
Parameter N (12)
Age (yrs)
Weight (kgs)
Height (cms)
BMI (kg/m2)
27.8 ± 3.9
68.6 ± 7.7
170.7 ± 4.9
23.5 ± 2.0
Values are Mean ±SD.
Figure 1. Shows laser Doppler flowmetry technique. Low
power laser light is used to illuminate tissue using a fibre
optic; The light is scattered by the static tissue structures
and moving blood cells; The moving blood cell impart a
Doppler Shift; An adjacent fibre detects light returned
from the tissue; This light contains Doppler shifted and Un
shifted light; The signal is processed to extract the signal
related to the moving red blood cells.
1. All completed study per protocol. Exclusion criteria
included: obesity (body mass index >30 kg/m2), under
weight (body mass index <18.5 kg/m2), any medication
with the potential to alter cardio vascular or thermaoregu-
latory control or response, allergies to hot peppers, and
various dermatological conditions or diseases.
The study protocol was approved by the institutional
human studies committee, Nizam’s Institute of Medical
Sciences, Hyderabad, India and complied with the Dec-
laration of Helsinki on Biomedical research Involving
Human Subjects. Before enrolment, all participants gave
informed consent in writing.
Each participant had an initial visit to th e experimental
laboratory, for a physical examination and a medical
history assessment. A 0.075% capsaicin cream (Asian
Herbex LTD, Hyderabad, India) was applied on the volar
Figure 2. Shows area of flare 30 minutes post-capsaicin
aspect of forearm of one hand to detect any adverse reac-
tions to capsaicin. In the absence of symptoms indicating
hypersensitivity, including an unusually painful or hy-
peremic response to capsaicin, the subjects were cleared
to participate in the stud y.
A Laser Doppler Flowmetry amplifier (BIOPAC Sys-
tems, Goleta, CA, USA) with an associated Laser Dop-
pler Flowmetry probe (TSD 142) was used to perform
the necessary measurements. Experiment was performed
in environmental conditions where the temperature was
maintained at ~23˚C ± 2 ˚C.
Application site (10 cm distal to elbow crease) were
marked on the volar aspect of the forearm of both non-
dominant and dominant hand with a soft pen. Prior to
any applications, Laser Doppler Flow (LDF) recording
were taken on volar aspect of both the forearms to serve
as a baseline measurement.
After the initial measurement, acute cap saicin applica-
tions (0.075%) were preceded on the non-dominant fore-
arm and placebo (containing ointment base only) appli-
cation to the dominant forearm. The blood flow response
was measured at 30 minutes post-capsaicin/placebo ap-
plication in the area within ring (Figure 2).
Statistical Analysis
Participant’s demographic data is presented as mean ±
SD, and pharmacodynamic parameters are presented as
mean, Standard Deviation (SD), Standard Error (SE) and
95% of Confidence Interval (CI).
To find out the differences between placebo and cap-
saicin treatment one way ANOVA was used. Paired t-test
was used to analyse the difference within the group, and
between the groups respectively. p < 0.05 was consid-
ered for statistical significance. All the statistical analysis
opyright © 2011 SciRes. PP
Determination of Capsaicin Induced Increase in Dermal Blood Flow Using Laser Doppler Flowmetry Technique 161
were performed using the Graph pad PRISM software 4
(Graph pad s of t ware In c. San Diego, Cali f ornia, USA).
3. Results
Dermal blood flow was determined in 12 healthy male
subjects’ with mean age, weight, height, and BMI (27.8
± 3.9 yrs), (68.6 ± 7.7 kgs), (170.7 ± 4.9 cms), and (23 .5
± 2.0 kg/m 2) respectively shown in Table 1.
Application of capsaicin didn’t produce any major
adverse events; however, there was local flare and mild
tingling sensation which disappeared after 4 hrs of ap-
There was no difference in blood flow at baseline be-
tween placebo and capsaicin forearm. Dermal blood flow
significantly increased in all the 12 subjects’ thirty min-
utes after 0.075% application of capsaicin ointment.
Dermal blood flow repr esented as Blood Perfusion Units
(BPU) obtained with placebo and capsaicin is given in
Table 2.
After 30 minutes of capsaicin application the mean
dermal blood flow significantly increased from 31.4 ±
3.1 BPU to 115. 7 ± 24.6 BPU, this increase was signifi-
cant (p < 0.001). Similarly, there was a significant dif-
ference in dermal blood flow change after 30 minutes
between placebo (32.1 ± 2.7 BPU) and capsaicin (115.7
± 24.6 BPU) application (p < 0.001).
The percentage change from baseline in dermal blood
flow in placebo arm and in capsaicin arm is shown in
Figure 3. Placebo application produced insignificant rise
Table 2. Showing cutaneous bl ood flow (in BPU) befor e and
post placebo/capsaicin application.
Blood Perfusion Units
(BPU) Blood Perfusion Units
Placebo Capsaicin
Baseline 30 minutes
post-application Baseline 30 minutes
Mean 29.8 32.1 31.4ns 115.7*,$
SD 11.9 9.5 10.7 85.4
SE 3.4 2.7 3.1 24.6
Lower 95%
CI of mean 22.2 26.0 24.6 61.4
Upper 95%
CI of mean 37.4 38.1 38.2
Abbreviations: SD; Standard Deviation, SE; Standard Error, CI; Con-
fidence Interval; ns = not significant compared to placebo; * = p < 0.001
compared to baseline; $ = p < 0.001 compared to placebo.
Figure 3. Showing % change in cutaneous blood flow (in
BPU) from baseline with placebo and capsaici n.
in blood flow by 13.2 ± 7.4%, while there was a signifi-
cant increase in dermal blood flow 30 minutes after the
application of 0.075% capsaicin (291.0 ± 85.3%). This
difference between placebo and capsaicin was highly
significant (p < 0.001).
4. Discussion
This is the first study to determine capsaicin-induced
neurogenic inflammation using Laser Doppler flowmetry
In the present study we have demonstrated the effect
of local application of capsaicin on microcirculation of
forearm skin in healthy male subjects using laser Dop-
pler flowmetry technique. Earlier technique of Laser
Doppler perfusion imaging has been described to have
good reproducibility to detect microvascular changes on
skin surface.
Exploration of microcirculation by laser Doppler
technology has often been considered poorly reproduci-
ble [19]. Introductio n of laser Doppler perfusion imaging
has considerably improved reproducibility of this tech-
nique [20-22]. As the clear guideline for measurement of
digital blood flow by laser doppler perfusion imaging are
available now, it has been regularly used to assess cuta-
neous blood flow of normal and irritated skin [20]. Ear-
lier study has revealed a dose-dependent increase in
digital blood flow after capsaicin application on forearm
In the present study application of capsaicin (0.075%)
Copyright © 2011 SciRes. PP
162 Determination of Capsaicin Induced Increase in Dermal Blood Flow Using Laser Doppler Flowmetry Technique
significantly increased dermal blood flow as compared to
placebo. Van der Schueren et al., have demonstrated the
increase in blood flow after application of 300 and 1000
micro grams of capsaicin while the application of 100
micro grams didn’t produce any increase in blood flow
In our study the blood flow measurement was carried-
out after 30 minutes application of capsaicin. It has been
shown that 1000 micrograms of capsaicin produced the
maximum response between 30 and 45 minutes after
application and at 60 minutes time point there was de-
crease in blood flow [23]. There was increase in blood
flow (291 ± 85.3 %) with 0.075% capsaicin application
compared to placebo in our study. Helme and McKernan
have extensively investigated the wide variation in size
and intensity of capsaicin induced flare response [7].
According to these authors, site of application and age
were the factors responsible for large variation. Gazerani
et al. recently found that capsaicin induced sensory and
vasomoto r responses were also g ender specific [24 ]. The
present study was conducted only in male gender. Het-
erogeneity in th e density an d function of capsaicin sensi-
tive nociceptive nerve endings of the dermal microcircu-
lation seem to be the most plausible explanation. There
may be variation in the response due to difference be-
tween the proximal and distal forearm, due to difference
in skin thickness [23]. We have thus applied the capsai-
cin 10 cms distal to elbow crease to avoid this site varia-
Munce and Kenney reported decrease in local skin
blood flow response in older participants than healthy
males [25]. Age had a significant effect on local vasodi-
lation with younger individuals having percentage of
maximal cutaneous vascular conductance (% CVCmax) at
least 2 times greater than seen in older group. Previous
observations of decrease flare size in older individuals
after acute application of capsaicin suggest that there is
reduction in reduced skin blood flow in these subjects [7].
We included only younger individuals, the average age
of participants in our study was 27.8 ± 3.9 yrs. Acute
capsaicin stimulates a specific population of sensory
nerves in the skin that possess capsaicin receptors, elic-
iting local release of vasoactive neurotransmitters from
their nerve endings [25]. The further use of our model
can have advantage in dose finding and proof of concept
5. Conclusions
The present study has shown an increase in the dermal
blood flow induced by topical application capsaicin on
the human forearm using laser Doppler flowmetry tech-
nique. Hence, this pharmacodynamic model which is non-
invasive, technically uncomplicated and sound, might
therefore facilitate the early evaluation of antagonists of
mediators involved in neurogenic inflammation, includ-
ing CGRP, TRPV1 and possibly, SP antagonists in hu-
6. Acknowledgements
The study was funded through the Indian Council of
Medical Research (ICMR) fund, Government of India.
The authors declare no financial conflict of interest con-
nected to this study and its results.
We thank the Director, Nizam’s institute for provid-
ing us the necessary infrastructure.
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