Chapter-8 Caffeine Introduction – Caffeine is a...
Transcript of Chapter-8 Caffeine Introduction – Caffeine is a...
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 186
Introduction – Caffeine is a pharmacologically active substance and
depending on the dose, can be a mild central nervous system
stimulant. Caffeine does not accumulate in the body over the course
of time and is normally excreted within several hours of consumption
[1-2].
In humans, caffeine acts as a central nervous system stimulant,
temporarily warding off drowsiness and restoring alertness. It is the
world's most widely consumed psychoactive drug, but, unlike many
other psychoactive substances, it is both legal and unregulated in
nearly all parts of the world [3].
Structure -
IUPAC Name - 3, 7-dihydro-1, 3, 7-trimethyl-1H-purine-2,6-dione.
- 1, 3, 7,-Trimethylxanthine.
- 1, 3, 7-Trimethyl-4, 6-dioxopurine
Formula - C8H10N4O2
Solubility - Freely soluble in chloroform, methanol and in
boiling water; sparingly soluble in water and in
ethanol (95 per sent)
Mol. Wt. - 194.19
Brand Name - Vivarin-200 mg [A]
- Stay awake-200 mg [B]
- Ra stay awake-200 mg [C]
Identification - Identification of pure drug is performed by FT-IR
(Shimadzu 8400s) and compared with standard
one [4].
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 187
Wave number (cm-1)
Fig. 8.1: Reference IR Spectrum of CFI
Fig. 8.2: IR Spectrum of pure CFI
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 188
Table 8.1: Characteristics absorption frequencies for identification of
pure CFI
S. No. Types of Vibrations Frequency (cm-1) 1. Ar. C – H Stretching 3113.21
2. Ar. C – H Bending 758.05
3. C – N Stretching 1359.86
4. C = O Stretching 1697.41
5. C = N 1599.04
6. Ar. C - C Stretching 1604.83
Bioavailability - 99%
Protein binding - 17% to 36%
Metabolism - Caffeine is metabolized in the liver into three primary
metabolites, paraxanthine (84%), theobromine (12%) and theophylline
(4%). Caffeine from coffee or other beverages is absorbed by the small
intestine within 45 minutes of ingestion and then distributed
throughout all tissues of the body [5]. Peak blood concentration is
reached within one hour [6]. Caffeine can also be absorbed rectally,
evidenced by the formulation of suppositories of ergotamine tartrate
and caffeine (for the relief of migraine) [7], chlorobutanol and caffeine
(for the treatment of hyperemesis) [8]. Caffeine is metabolized in
the liver by the cytochrome P450 oxidase enzyme system (to be specific,
the isozyme) into three metabolic dimethylxanthines [9].
Half – Life - 5 hrs
Excretion - urine
History - Caffeine was first isolated from coffee in 1820 by the German
chemist Friedlieb Ferdinand Runge, and then independently in 1821
by French chemists Pierre Robiquet, Pierre Pelletier, and Joseph
Caventou. Pelletier coined the word "caffeine" from the French word
for coffee (café), and this term became the English word "caffeine".
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 189
The history of coffeine has been recorded as far back as the
ninth century. During that time, coffee beans were available only in
their place of origin, Ethiopia. Legends trace the discovery of coffee
either to a Sufi dervish named Omar, or to a goatherder named Kaldi,
who observed goats become elated and sleepless at night after grazing
on coffee shrubs and, upon trying the berries the goats had been
eating, experienced the same vitality [10].
In 1819, the German chemist Friedlieb Ferdinand Runge isolated
relatively pure caffeine for the first time; he called it "Kaffebase" (i.e.,
a base that exists in coffee) [11].
The structure of caffeine was elucidated near the end of the 19th
century by Hermann Emil Fischer, who was also the first to achieve
its total synthesis. This was part of the work for which Fischer was
awarded the Nobel Prize in 1902 [12].
Use - Caffeine which is found in tea and coffee imparts bitterness and
also acts as a flavor constituent. It is a mild nervous stimulant
towards drowsiness and fatigue. Caffeine is used as a drug on the
basis of its effect on respiratory, cardiovascular and the central
nervous system. It is included with ergotamine in some anti-migraine
preparations, the object being to produce a mildly agreeable sense of
alertness. Caffeine is administered in the treatment of mild respiratory
depression caused by central nervous system depressants such as
narcotic.
Adverse effect - Common adverse effects include drowsiness,
headaches, migraines, confusion, Incontinence and liver damage.
Bio–Analytical methods -
Several methods have been reported for the determination of
CFI standards and in pharmaceutical preparations.
B. B. Fredholm et al., have described the actions of caffeine in
the brain with special reference to factors that contribute to its
widespread use [13].
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 190
A. Astrup et al., have studies caffeine a double-blind, placebo
controlled study of its thermogenic, metabolic, and cardiovascular
effects in healthy volunteers [14].
J. M. Kalmar et al., have introduced the effects of caffeine on
neuromuscular function [15].
E. Hogervorst et al., have described the caffeine improves
physical and cognitive performance during exhaustive exercise [16].
I. Hindmarch, et al., have studied the effects of black tea and
other beverages on aspects of cognition and psychomotor performance
[17].
M. Johnson-Kozlow, et al., have described the coffee consumption
and cognitive function among older adults [18].
M. Kivipelto, et al, introduced the midlife vascular risk factors
and Alzheimer's disease in later life: longitudinal, population based
study [19].
C. A. Manning, et al., have studied the glucose enhancement of
24-h memory retrieval in healthy elderly humans [20].
P. J. Mitchell, et al., have described the effects of caffeine, time
of day and user history on study-related performance [21].
Caffeine an alkaloid of the methylxanthine family is a naturally
occurring substance found in the leaves, seeds or fruits of over 63
plants species worldwide. The most commonly known sources of
caffeine are coffee, cocoa beans, cola nuts and tea leaves. In its pure
state, it is an intensely bitter white powder. Various manufacturers
market caffeine tablets, claiming that using caffeine of pharmaceutical
quality improves mental alertness. These effects have been borne out
by research that shows that caffeine use results in decreased fatigue
and increased attentiveness [22].
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 191
Determination of λmax using solvent
The pure form of CFI was accurately weighed 10 mg and
dissolved in 100 mL of medium (PEG 4000 9× 10-5 M). The Stock
solution 100 μg/mL was further diluted 1.0 mL in 100 mL media to
give a concentration of 1 μg/mL, the absorption spectra were obtained
with Elico 164 UV-Visible double beam spectrophotometer a scan
range of 200-400 nm and determine the maximum absorbance of drug
at λmax 270 nm. (Fig. 8.3.)
Fig. 8.3: Determination of λmax
using solvent
Determination of calibration curve using solvent
The stock solution (100 μg/mL) of CFI was prepared by
dissolving 10 mg of CFI in 100 mL volumetric flask and made upto
100 mL by aqueous methanol.
Aliquots of 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, 1.0 mL, 1.2 mL, 1.4
mL and 1.6 mL, of the stock solution were pipetted out into 100 mL
volumetric flask. The volume was made up to the mark with aqueous
methanol. The absorbance of prepared solutions of CFI was
measurement at λmax
270 nm using against aqueous methanol blank.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 192
y = 0.054x + 0.002R² = 0.999
0.000.100.200.300.400.500.600.700.800.901.00
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
Abso
rban
ce
Conc. (µg /mL)
Fig. 8.4: Determination of calibration curve by using solvent
Solubility measurements:
The solubility of CBZ was measured in different media such as
distilled water, CTAB, PEG- 400, mixed CTAB + PEG 400, PEG- 4000,
PVP 44000, mixed PEG 4000 + PVP 400O. An excess amount of drug
(25 mg) was then added to 50 mL of each fluid in conical flask. The
mixture was stirred on a magnetic stirrer for half an h. 5.0 mL aliquot
was withdrawn at 10 min. interval and filter immediately using a 0.45
μm syringe filter, diluted with water and then assayed
spectrophotometrically at λmax
270 nm. Shaking continued until two
consecutive estimations are the same.
Table 8.2: Solubility of CFI in different media
S. No.
Sample (each fluid at their
CMC values)
Wt. of drug (mg)
Overall volume
(mL)
Abs. at λ
max
270 nm
Solubility increase in fold
1. CBZ + Distilled water 25 50 0.092 1.00 2. CBZ + CTAB 25 50 0.392 4.26 3. CBZ + PEG 400 25 50 0.561 6.09 4. CBZ + CTAB+PEG 400 25 50 0.442 4.80 5. CBZ + PEG 4000 25 50 0.998 10.84 6. CBZ + PVP 44000 25 50 0.720 7.82
7. CBZ +PEG 4000+ PVP44000
25 50 0.572 6.21
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 193
Polymeric surfactant PEG-4000 (9× 10-5 M) grandly increases
the solubility of CFI. At CMC, the suability of CFI was increased by
10.84 fold. Among the different solvent tested, PEG 4000 shows the
highest increase in the solubility.
Micellization of biologically active substances is a rather general
phenomenon, since it is believed that the increase in the
bioavailability of a lipophilic drug upon oral administration is caused
by drug solubilization in the gut by naturally occurring biliary lipid
fatty acid-containing micelles produced by the organism as a result of
the digestion of dietary fat. On the other hand, surfactant micelles are
widely used as adjuvant and drug carrier systems in many areas of
pharmaceutical technology and controlled drug delivery research
[23-25].
Fig. 8.5: Solubility enhancement by micellization
The ‘ideal’ pharmaceutical micelle should possess a suitable size
(from 10 to 100 nm), demonstrate sufficiently high stability both in
vitro and in vivo (i.e. have a good combination of reasonably low CMC
value and reasonably high kinetic stability), be able to stay in the body
long enough and still eventually disintegrate into bio-inert and non-
toxic unimers that should be easily cleared from the body, and carry a
substantial quantity of a micelle-incorporated pharmaceutical agent.
To meet these ‘net’ requirements, the core compartment should
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 194
demonstrate high loading capacity, controlled release profile for the
incorporated drug, and good compatibility between the core-forming
block and incorporated drug.
The kinetic stability (the actual rate of micelle dissociation below
CMC) depends on many factors including the physical state of the
micelle core contents of a solvent inside the core the size of a
hydrophobic block and the hydrophobic/hydrophilic ratio [26-28].
The process of solubilization of water sparingly soluble drugs by
micelle forming amphiphilic block copolymers was investigated both
as a theoretical and practical problem [29]. It was shown that the
solubilization process strongly depends on the type and efficacy of the
interactions between a solubilized drug and micelle core-forming
hydrophobic block of a copolymer. However, the interactions between
a drurg to be solubilized and the hydrophilic corona forming block as
well as interfacial interactions between drug and solvent (methanol)
may also influence the solubilization process. Recent mathematical
simulation of the solubilization process [30], demonstrated that the
initial solubilization proceeds via the displacement of solvent
(methanol) molecules from the micelle core, and later a solubilized
drug begins to accumulate in the very center of the micelle core
pushing hydrophobic blocks away from this area. Extensive
solubilization may result in some increase of micelle size due to the
expansion of' its core with a solubilized drug. The compatibility
between the loaded drug and core-forming component determines the
efficacy of drug incorporation [31].
Determination of λmax using medium (PEG-4000 at CMC 9× 10-5 M)
The pure form of CFI was accurately weighed 10 mg and
dissolved in 100 mL of medium (PEG 4000 at CMC 9× 10-5 M). Stock
solution 100 μg/mL. The stock solution was further diluted 1.0 mL
(above solution) in 100 mL medium to obtain a concentration of 1
μg/mL. The absorption spectra were obtained with Elico 164 UV-
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 195
Visible double beam spectrophotometer, a scan range of 200-400 nm
and determine the maximum absorbance of drug at λmax 272 nm.
Fig 8.6: Determination of λ
max using medium
Preparation of stock solution from standard solution:
The stock solution was prepared from the standard solution.
Aliquots of 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, 1.0 mL, 1.2 mL, 1.4 mL,
1.6 mL and 1.8 mL of the standard solution were pipette out into 10
ml volumetric flask. The volume was make up to the mark with
medium. To obtain a concentrations of 2, 4, 6, 8, 10, 12, 14, 16, and
18 µg/mL.
The absorbance of prepared solutions of CFI was measured at
λmax 272 nm using against medium blank. Averages of such eight set
of values were taken for standard calibration curve.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 196
y = 0.050x + 0.001R² = 0.999
0.000.100.200.300.400.500.600.700.800.901.00
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0
Abso
rban
ce
Conc. (µg /mL)
Fig 8.7: Determination of calibration curve by using medium
Table 8.3: Quality Control Parameters
S.
No. Parameters
Solvent
(methanol)
Media (PEG-4000
- 9× 10-5 M)
1. λmax (nm) 272 272
2. Beer’s Range (µg /mL) 2-16 2-18
3. Molar Absorptivity (L mol-1 cm-1) 1.03×104 1.05×104
4. Sandell’s Sensitivity (µg cm-2) 1.871 0.018
5. Regression equation 0.999 0.999
6. Intercept 0.002 0.001
7. Slope 0.054 0.050
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 197
In Vitro dissolution study:
1. Apparatus: Electrolab TDT – 08L USP apparatus.
2. Dissolution Media: PEG- 4000 at CMC 9× 10-5 M
3. Rotation speed: 100 rpm.
4. Preparation of CFI standard solution: 10 mg CFI standard was
weighed precisely, put in 100 mL volumetric flask and made up
to the mark with dissolution media.
5. Test preparation: Dissolution testing was performed on tablets
containing 10 mg CFI in 9× 10-5 M PEG 4000 (37°C ± 0.5°C) using
paddle method (USP apparatus- II) at 100 rpm. Sample of 5 mL
were withdrawn at regular time intervals, replaced by fresh medium
and spectro-photometrically analyzed at λmax 272 nm after
filtration through 0.45μm syringe filter. All dissolution tests were
performed in triplicate.
6. Time point: Dissolution amount was measured separately at 05,
10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 minutes.
The percentage of drug released obtained by using by following
formula -
Sample Absorbance Standard weight Dilution Medium × × × × Potency Standard Absorbance Dilution 1 Label Claim
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 198
Table8.4: Sample absorbance at different time intervals
S. No. Time (min) Absorbance
Brand- A Brand- B Brand- C 1 5 0.123 0.136 0.111
2. 10 0.235 0.263 0.193
3. 15 0.333 0.369 0.299
4. 20 0.397 0.433 0.374
5. 25 0.451 0.466 0.438
6. 30 0.485 0.498 0.460
7. 35 0.515 0.526 0.498
8. 40 0.538 0.544 0.527
9. 45 0.549 0.565 0.546
10 60 0.571 0.577 0.569
Standard Abs. 0.585
Table 8.5: % drug release of various formulations in PEG 4000 at
different time
S. No. Time (min) % Drug release
Brand- A Brand- B Brand- C 1 05 21.09 23.32 19.04
2. 10 40.31 45.11 33.10
3. 15 57.12 63.29 51.29
4. 20 68.10 74.27 64.15
5. 25 77.36 79.93 75.13
6. 30 83.19 85.42 78.90
7. 35 88.34 90.22 85.42
8. 40 91.94 93.31 90.40
9. 45 94.17 96.91 93.66
10 60 97.94 98.97 97.60
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 199
Table 8.6: log time, square root of time and log % of drug relea
S. No.
Time (min)
log time
Square root of time
log % drug release
Brand-A Brand-B Brand-C
1 05 0.69 2.23 1.32 1.36 1.27
2. 10 1.00 3.16 1.60 1.65 1.51
3. 15 1.17 3.87 1.75 1.80 1.71
4. 20 1.30 4.47 1.83 1.87 1.80
5. 25 1.39 5.00 1.88 1.90 1.87
6. 30 1.47 5.47 1.92 1.93 1.89
7. 35 1.54 5.91 1.94 1.95 1.93
8. 40 1.60 6.32 1.96 1.96 1.95
9. 45 1.65 6.70 1.97 1.98 1.97
10 60 1.77 7.74 1.99 1.99 1.98
Kinetics of drug release
The dissolution data of three brands of CFI tablets (200 mg)
were applied to Zero order, First order, Higuchi model and Korsmeyer
–Peppas models.
Table 8.7: Kinetic parameters for Zero-Order
% Drug release k x mole min-1
Time
[min] Brand-A Brand-B Brand-C Brand-A Brand-B Brand-C
0 0.00 0.00 0.00 0.0000 0.0000 0.0000 5 21.09 23.32 19.04 4.2180 4.6640 3.8080 10 40.31 45.11 33.10 4.0310 4.5110 3.3100 15 57.12 63.29 51.29 3.8080 4.2193 3.4193 20 68.10 74.27 64.15 3.4050 3.7135 3.2075 25 77.36 79.93 75.13 3.0944 3.1972 3.0052 30 83.19 85.42 78.90 2.7730 2.8473 2.6300 35 88.34 90.22 85.42 2.5240 2.5777 2.4406 40 91.94 93.31 90.40 2.2985 2.3328 2.2600 45 94.17 96.91 93.66 2.0927 2.1536 2.0813 60 97.94 98.97 97.60 1.6323 1.6495 1.6267
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 200
Fig. 8.8: Dissolution profile (n=3) of three commercial products of CFI
in polymeric micellar media (Zero order plot)
Fig. 8.9: Regression plot for zero order
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 201
Table 8.8: First - Order rate constant
log % Drug release kx10-1min-1
Time
[min] Brand-A Brand-B Brand- C Brand- A Brand- B Brand- C
0 0.00 0.00 0.00 0.0000 0.0000 0.00000
5 1.32 1.36 1.27 3.7983 3.7985 2.4018
10 1.60 1.65 1.51 1.8992 1.8993 1.9370
15 1.75 1.80 1.71 1.1602 1.1627 1.1403
20 1.83 1.87 1.80 0.8321 0.8396 0.8124
25 1.88 1.90 1.87 0.6480 0.6617 0.6256
30 1.92 1.93 1.89 0.5287 0.5424 0.5158
35 1.94 1.95 1.93 0.4485 0.4590 0.4330
40 1.96 1.96 1.95 0.3885 0.4003 0.3750
45 1.97 1.98 1.97 0.3435 0.3522 0.3299
60 1.99 1.99 1.98 0.2551 0.2629 0.2462
Fig.8.10: First order plot
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 202
Fig.8.11: Regression plot for first order
Table 8.9: Higuchi rate constant
log % Drug Release kxt1/2 min-1/2
Time [min]
Min1/2 t1/2 Brand-A Brand-B Brand- C Brand- A Brand-B Brand-C
0 0.00 0.00 0.00 0.00 0.0000 0.0000 0.0000
5 2.23 21.09 23.32 19.04 9.4574 10.4574 8.5381
10 3.16 40.31 45.11 33.10 12.7563 14.2753 10.4747
15 3.87 57.12 63.29 51.29 14.7597 16.3540 13.2532
20 4.47 68.10 74.27 64.15 15.2349 16.6152 14.3512
25 5.00 77.36 79.93 75.13 15.4720 15.9860 15.0260
30 5.47 83.19 85.42 78.90 15.2084 15.6161 14.4241
35 5.91 88.34 90.22 85.42 14.9475 15.2657 14.4535
40 6.32 91.94 93.31 90.40 14.5475 14.7642 14.3038
45 6.70 94.17 96.91 93.66 14.0552 14.4642 13.9791
60 7.74 97.94 98.97 97.60 12.6537 12.7868 12.6098
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 203
Fig. 8.12: Higuchi plot
Fig. 8.13: Regression plot for Higuchi model
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 204
Table 8.10: Korsmeyer-Peppas rate constant
log % drug release kx10-1min-1
Time
[min]
log
time Brand-A Brand-B Brand-C Brand-A Brand-B Brand-C
0 0.00 0.00 0.00 0.00 0.0000 0.0000 0.0000
5 0.69 1.32 1.36 1.27 1.8437 1.9593 1.7044
10 1.00 1.60 1.65 1.51 0.7713 0.8196 0.6991
15 1.17 1.75 1.80 1.71 0.4796 0.5086 0.4511
20 1.30 1.83 1.87 1.80 0.3386 0.3566 0.3205
25 1.39 1.88 1.90 1.87 0.2602 0.2708 0.2492
30 1.47 1.92 1.93 1.89 0.2094 0.2169 0.1984
35 1.54 1.94 1.95 1.93 0.1347 0.1398 0.1289
40 1.60 1.96 1.96 1.95 0.0982 0.1013 0.0940
45 1.65 1.97 1.98 1.97 0.0638 0.0661 0.0614
60 1.77 1.99 1.99 1.98 0.0451 0.0465 0.0432
Fig. 8.14: Korsmeyer Plot
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 205
Fig. 8.15: Regression plot for Korsmeyer model
Table 8.11: Regression (R2) value of kinetic models
S.
No Brands
Zero
order
First
order
Higuchi
model
Korsmeyar
model ‘n’exponent
1. A 0.828 0.479 0.992 0.900 0.48
2. B 0.795 0.451 0.993 0.881 0.49
3. C 0.862 0.513 0.994 0.921 0.46
Characterization of nano particles
Particle size
The volume mean diameter (VMD) of particles was determined
using a Mastersizer (Malvern instruments UK). The results obtained
were analyzed by the Fraunhofer model and are represented as VMD
(µm).
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 206
Fig.8.16: Size distribution of CFI Scanning electron microscopy
In SEM, a source of electrons is focused in vacuum into a fine
probe that is rastered over the surface of the specimen. The electron
beam passes through scan coils and objective lens that deflect
horizontally and vertically so that the beam scans the surface of the
sample. The ultimate resolution of the SEM levels out near 0.6nm at
5kV. In Scanning Trasmission Electron Microscopy in which internal
microstructure images of thin specimens are obtained, achieved
resolution is up to 1.5nm at 30Kv [32].
Transmission electron microsoopy
Transimission Electron Microscopy (TEM) is a technique where
an electron beam interacts and passes through a specimen. The
electrons are emitted by a source and are focused and magnified by a
system of magnetic lenses. The electron beam is confined by the two
condensers lenses which also control the brightness of the beam,
passes the condenser aperture and “hits” the sample surface [33].
The operation of TEM requires an ultra high vacuum and a high
voltage. The first step is to find the electron beam, so the lights of the
room must be turned off. Through a sequence of buttons and
adjustments of focus and brightness of the beam, we can adjust the
settings of the microscope so that by shifting the sample holder find
the thin area of the sample. Then tilting of the sample begins by
rotating the holder. This is a way to observe as much areas as we can,
so we can obtain as much information [34].
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 207
Fig. 8.17: SEM Image of CFI
Fig. 8.18: TEM Image of CFI
220 nm
130 nm
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 208
Results and discussion
The solubility of CFI was determined at 37ºC ± 0.5ºC in different
fluids is listed in Table 8.2. PEG 4000 greatly increases the solubility
of CFI. The surprising increase in solubility of CFI by nearly 10.84 fold
is found in PEG - 4000.
Mechanism and kinetics of drug release - To know the mechanism
of drug release from these formulations, the data were treated
according to zero-order (cumulative amount of % drug release vs. time
and its regression plots are shown in Fig. 8.8 and 8.9), first order (log
cumulative % of drug release vs time and its regression plot in Fig.
8.10 and 8.11), Higuchi’s (cumulative % of drug release vs. square
root of time and its regression plot in Fig. 8.12 and 8.13), Korsmeyer
plot (log cumulative % of drug release vs log time and its regression
plots in Fig.8.14 and 8.15) and equations. Diffusion is related to
transport of drug from the dosage matrix in to the in vitro study fluids
depending on the concentration. As gradient varies, the drug is
released, and the distance for diffusion increases, which is referred as
Higuchi’s kinetics. In our experiment, the in vitro release profile of CFI
from all the brands could be best expressed by Higuchi’s equation, as
the plot showed high linearity (r2 > 0.994). The slope of the regression
line from Higuchi’s plot indicates the rate of drug release. The
comparative Higuchi’s release rates for different brands are presented
in Table 8.9, Fig. 8.12 and Fig.8.13 reveal that the k obtained from
Higuchi’s model shows better result with high correlation coefficient
(r2 =0.994).
The Korsmeyer-Peppas model is used to analyze drug release
from pharmaceutical dosage forms when the release mechanism is not
well known or when more than one type of release phenomena is
involved. The exponent, termed the release exponent “n”, was studied
by Peppas and coworkers to characterize different drug release
mechanisms from thin films. They noted that profile with n = 0.5
exhibited a drug release mechanisms controlled by Fickian diffusion,
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 209
while drug release rate was independent of time and controlled by a
swelling mechanism when n = 1. In the current study, the value of
release rate exponent (n), ranged between 0.46–0.49. Values of n
between 0.5 and 1.0 were regarded as an indicator for the
superposition of both phenomena, and the drug release mechanism
follow was Fickian diffustion.
Polymer micelles have been extensively worked as drug carriers
[35]. Conjugating to ligands such as antibodies can enhance targeting
potential of micelles. micelles is one such novel approach in which
antibody conjugated polymeric micelles containing anti-stimulant
drugs was prepared and results demonstrated effective delivery at
BBB site [36]. Targeting has also been achieved in other drugs with
reduced toxicity [37]. Novel polymeric micelles with targetability and
stimuli sensitivity have emerged as promising carriers in gene and
drug delivery, and can potentially establish landmarks in the future of
drug delivery systems [38].
Micelles as drug carries provide a set of advantage- they
physically entrap sparingly soluble pharmaceutical and deliver them
to the described site of action at concentration that can exceed their
intrinsic water solubility and thus bioavailability. The stability of the
drug is also increased through micelle incorporation. Further more,
undesirable side effects are lessened, as contact of the drug with
inactivating species, such as enzymes present in biological fluids, are
minimized, in comparison with free drug [39-41]. They can be
prepared in large quantities easily and reproducibly [42-43]. The most
important feature of micellar delivery systems, which distinguish them
from other particulate drug carriers, line in their small size (1-100 nm)
and the narrow size distribution [44].
Micelles made of polymeric surfactant are widely used as
adjuvant and drug carrier system in many areas of pharmaceutical
technology and controlled drug delivery [45-50].
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 210
Particle size, charge determination and morphology of final
dissoluted drug were examined by Zeta sizer show result 150.6 nm
and TEM show the result 130 nm. As shown in the Fig. 8.16 and 8.18.
Scanning Electron Microscopy (SEM) to examine the surface
topography morphology of fractured of sectioned surface, to analyze
the surface of polymeric drug delivery system that can provide
important information about the SEM analysis. The result for
scanning microscope 220 nm is shown in the Fig.8.17. These images
indicate the smooth regular and spherical surfaces of all
nanoparticles, As seen in the photomicrographs, nanoparicles seen
smaller than the particle size determined by DLS.
As previously discussed, the property of nanoparticle
formulations that make this approach highly beneficial is related to
the surface properties imparted on nanometer-sized entities. Although
in recent years, tremendous emphasis and focus have been placed on
nanotechnology research, as early as 1906, Ostwald published “The
World of the Neglected Dimensions,” wherein colloidal nanoparticles
exhibited special properties that resided between the molecular and
the material sciences. In practice, applying NanoCrystal Technology or
one of the alternative nanoparticle formulation approaches to the
many formulation and performance issues associated with sparingly
water-soluble compounds in the pharmaceutical industry provide
many benefits. These benefits can be categorized into three major
areas: formulation-performance improvements related to enhanced
dissolution, safer and more patient-compliant dosage forms, and the
potential for dose escalation for improvements in efficacy.
CNS drugs represent one of the largest segments of the total
drug market, and it constitutes the segment with the greatest
potential for substantial growth in the years ahead, largely because of
the rapidly increasing numbers of individuals with CNS disorders.
However, most CNS disorders are not treated well, if at all, and the
time taken for CNS drugs to get to market is longer than other
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 211
therapeutic areas, and the probability of getting to market is lower.
Thus, there is a clear need for CNS drug discovery to become more
efficient and more effective in order to meet the burgeoning need for
CNS therapeutics. A number of bottlenecks have been identified; one
of the key factors is the failure to pay sufficient attention to the
prediction and assessment of the ability of compounds to cross the
BBB.
There is a great hope that this problem can be tackled through
applications nanobiotechnology. Nanoplatforms can be used for
incorporation of multiple drugs, which means patient compliance
against continuous administration of drugs can be minimized. To
transport nano drugs across BBB. There are still many questions to
resolve before the translation of the research in nanocarriers to
clinical reality. However more research needed to be done regarding
the safety, immunogenicity and toxicity of the solid polymeric
nanoparticles as a whole after chronic systemic administration and
can be accomplished in future with interdisciplinary research
collaborations approaches between academia and Pharma -industry
will hopefully advance nanocarrier systems which can smartly and
clinically deliver any molecular neuro-therapeutic to the human brain.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 212
References 1. M. J. Aurnaud, Prog. Drug, 1987, 31, 273.
2. J. J. Barone, H. R. Roberts, Food Chem. Toxicol., 1996, 34,119.
3. Bolton, Sanford, Gary Null, Orthomole. Psychi., 1981, 10, 202 – 211.
4. K. Florey, “Analytical Profiles of Drug Substances” Elsevier,
Academic Press, New York, 1980, 9, 87-106.
5. A. Liguori, J. R. Hughes, J. A. Grass, Pharmacol. Biochem.
Behav., 1997, 58, 721–6.
6. McArdle, William Exercise Physiology. 7th ed., Baltimore, MD:
Lippincott Williams and Wilkins, 2010, 559.
7. J. R. Graham, N. Engl. J. Med., 1954, 250, 936–8.
8. H. B. Brodbaek, P. Damkier, Ugeskr. Laeg., 2007, 169, 2122-2123.
9. R. K. Verbeeck, Eur. J. Clin. Pharmacol., 2008, 64, 1147–61
10. R. Baselt, Disposition of Toxic Drugs and Chemicals in Man (9thed.).
C. A. Seal Beach, Biomedical Publications, 2011, 236–9.
11. L. T. Benjamin, A. M. Rogers, A. Rosenbaum, J. Hist. Behav.
Sci., 1991, 27, 42–55.
12. H. J. Théel, Nobel Prize Presentation Speech, 1902.
13. B. B. Fredholm, K. Battig, J. Holmen, A. Nehlig, E. E. Zvartau,
Pharmacol. Rev., 1999, 51, 83-133.
14. A. Astrup, S. Toubro, Am. J. Clin. Nutr., 1990, 51,759-67.
15. J. M. Kalmar, E. Cafarelli, J. Appl. Physiol., 1999, 87, 801-808
16. E. Hogervorst, S. Bandelow, J. Schmitt, R. Jentjens, M. Oliveira,
J. Allgrove, T. Carter, M. Gleeson, Med. Sci. Sports. Exerc.,
2008, 40, 1841-51.
17. I. Hindmarch, P. T. Quinlan, K. L. Moore, C. Parkin, Psychopharm.,
1998, 139, 230-8.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 213
18. M. Johnson-Kozlow, D. Kritz-Silverstein, E. Barrett-Connor, D.
Morton, Am. J. Epidemiol., 2002, 156, 842-50.
19. M. Kivipelto, E. Helkala, M. P. Laakso, T. Hänninen, M. Hallikainen,
K. Alhainen, H. Soininen, J. Tuomilehto, A. Nissinen, B. M. J.,
2001, 322, 1447-1451.
20. C. A. Manning, W. S. Stone, D. L. Korol, P. E. Gold, Behav. Brain
Res., 1998, 93, 71-6.
21. P. J. Mitchell, J. R. Redman, Psychopharm., 1992, 109, 121-6.
22. M. S. Morris, P. F. Jacques, I. H. Rosenberg, J. Selhub, Ameri.
J. Clin. Nutri., 2001, 73, 927-933.
23. A. A. Gabizon, Adv. Drug Deliv. Rev., 1995, 16, 285-294.
24. T. M. Allen, C. B. Hansen, D. E. L. Manenez, Adv. Drug Deliv.
Rev., 1995, 16, 267-284.
25. V. P. Torchilin, A. L. Klibanov, L. Huang, S. O. Donnell, N. D.
Nossiff, B. A. Khaw, FASEB J. 1992, 6, 2716-2719.
26. M. Tin, A. Qin, C. Ramireddy, S. E. Webber, P. Munk, Z. Tunzar,
K. Prochazka, Langumir, 1993, 9, 1741-1748.
27. Y. Wang, C. M. Kaush, M. Chun, R. P. Quirk, W. L. Mattice,
Micromolecules, 1995, 28, 904-911.
28. S. Creutz, J. Van Stam, F. C. De Schryver, R. Jerome, Micromolecules,
1998, 31, 681-689.
29. R. Nagarajan, K. Ganesh, Micromolecules, 1989, 22, 4312.
30. L. Xing, W. L. Mattice, Langmuir, 1998, 14, 4074-4080.
31. C. Allen, D. Maysinger, A. Eisenberg, Coll. Surf. Biointer., 1999, 16,
1-35.
32. M. Von Heimendahl, W. Bell, G. Thomas, J. Appli. Phy., 1964,
35 3614.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 214
33. C. R. Brundle, A. Charles, Evans Jr, Shaun Wilson. Encyclopedia
of Materials Characterization, Butterworth-Heinemann Publications,
1992.
34. M. Joachim, A. Lucille, T. Kamino, J. Michael. TEM Sample
Preparation and FIB-Induced Damage. Mrs Bulletin, 32, May
2007.
35. M. C. Jones, J. C. Leroux, Eur. J. Pharm. Biopharm., 1999, 48,
101-111.
36. V. P. Torchilin, A. N. Lukyanov, G. Zhonggao, P. B. Sternberg,
Proc. Natl. Acad. Sci. U.S.A., 2003, 100, 6039-6044.
37. Y. Mizamura, Y. Matsumura, T. Hamaguchi, N. Nishiyama, K.
Kataoka, T. Kawaguchi, W. J. Hrushesky, F. Moriyasu, T.
Kakizoe, Jpn. J. Can. Res., 2011, 92, 328-336.
38. N. Nishiyama, Y. Bae, K. Miyata, S. Fukushima, K. Kataoka, Drug
Discov. Today Tech., 2005, 2, 21-26.
39. M. Yokoyama, M. Miyauchi, N. Yamada, T. Okano, Y. Sakuari,
K. Kattaoka, S. Inoue, Can. Res., 1990, 50, 1693-1700.
40. V. H. L. Lee, A. Yamamoto, Adv. Drug Deliv. Res., 1990, 4, 171-207.
41. V. P. Torchilin, J. Control. Rel., 2001, 73, 137-172.
42. K. Kataoka, J. Macromol. Sci. Pure Appl. Chem, 1994, 31, 1759-
1769.
43. M. Yokoyama, (Ed.) Novel Possive Targetable Drug Delivery with
Polymeric Micelles, Academic Press, San Diego, 1998, 193-229.
44. A. T. Florence, N. Hussain, Adv. Drug Deliv. Rev., 2001, 50, 69-89.
45. S. N. Mailk, D. H. Canaham, M. W. Gouda, J. Pharm. Sci.,1975,
64, 987-990.
46. K. Takada, H. Yoshimura, N. Shibata, Y. Masuda, H. Yoshikawa,
S. Muranishi, T. Yasumura, T. Oka, J. Pharmacobio- Dyn., 1986,
6, 156-160.
Chapter-8 Caffeine
Department of Chemistry, Dr. Hari Singh Gour Central University, Sagar (M.P.) 215
47. D. D. Lasic. Nature, 1992, 355, 279-280.
48. G. Schubiger, J. Gruter, M. J. Shearer, J. Pediatr. Gastroenterol.
Natr., 1997, 24, 280-284.
49. P. A. Redondo, A. I. Alvarez, J. L. Garcia, C. Villaverde, J. G.
Prieto, Biopharm. Drug Disos., 1998, 19, 65-70.
50. H. A. Bardelmeijer, M. Ouwehand, M. M. Malingre, J. H. Schellens,
J. H. Beijnen, O. Van Tellingen, Can. Chemother. Pharmacol.,
2002, 49, 119-125.