Dissolution

July 26, 2020April 18, 2012 by Anand Bhumkar

Dissolution

Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. For the dissolution of solids, the process of dissolution can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent

The rate of dissolution quantifies the speed of the dissolution process.

The rate of dissolution depends on:

nature of the solvent and solute
temperature (and to a small degree pressure)
degree of undersaturation
presence of mixing
interfacial surface area
presence of inhibitors (e.g., a substance adsorbed on the surface).

The rate of dissolution can be often expressed by the Noyes-Whitney Equation or the Nernst and Brunner equation^[1] of the form:

$\frac {dm} {dt} = A \frac {D} {d} (C_s-C_b)$

where:

m – amount of dissolved material, kg

t – time, seconds

A – surface area of the interface between the dissolving substance and the solvent, m²

D – diffusion coefficient, m²/s

d – thickness of the boundary layer of the solvent at the surface of the dissolving substance, m

C_s – concentration of the substance on the surface, kg/m³

C_b – concentration of the substance in the bulk of the solvent, kg/m³

For dissolution limited by diffusion, C_s is equal to the solubility of the substance.

When the dissolution rate of a pure substance is normalized to the surface area of the solid (which usually changes with time during the dissolution process), then it is expressed in kg/m²s and referred to as “intrinsic dissolution rate”. The intrinsic dissolution rate is defined by the United States Pharmacopeia.

Dissolution rates vary by orders of magnitude between different systems. Typically, very low dissolution rates parallel low solubilities, and substances with high solubilities exhibit high dissolution rates, as suggested by the Noyes-Whitney equation. However, this is not a rule.

Diffusion

July 26, 2020April 18, 2012 by Anand Bhumkar

Diffusion describes the spread of particles through random motion from regions of higherconcentration to regions of lower concentration. The time dependence of the statistical distribution in space is given by the diffusion equation. The concept of diffusion is tied to that of mass transferdriven by a concentration gradient. Diffusion is invoked in the social sciences to describe the spread of ideas.

Fick’s laws of diffusion describe diffusion and can be used to solve for the diffusion coefficient, D. They were derived by Adolf Fick in the year 1855.

Fick’s first law relates the diffusive flux to the concentration under the assumption of steady state. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative). In one (spatial) dimension, the law is

$\bigg. J = - D \frac{\partial \phi}{\partial x} \bigg.$

where

$J$ is the “diffusion flux” [(amount of substance) per unit area per unit time], example $(\tfrac{\mathrm{mol}}{ \mathrm m^2\cdot \mathrm s})$ . $J$ measures the amount of substance that will flow through a small area during a small time interval.

$\, D$ is the diffusion coefficient or diffusivity in dimensions of [length² time⁻¹], example $(\tfrac{\mathrm m^2}{\mathrm s})$

$\, \phi$ (for ideal mixtures) is the concentration in dimensions of [(amount of substance) length⁻³], example $(\tfrac\mathrm{mol}{\mathrm m^3})$

$\, x$ is the position [length], example $\,\mathrm m$

Fick’s second law predicts how diffusion causes the concentration to change with time:

$\frac{\partial \phi}{\partial t} = D\,\frac{\partial^2 \phi}{\partial x^2}\,\!$

Where

$\,\phi$ is the concentration in dimensions of [(amount of substance) length⁻³], example $(\tfrac\mathrm{mol}{m^3})$
$\, t$ is time [s]
$\, D$ is the diffusion coefficient in dimensions of [length² time⁻¹], example $(\tfrac{m^2}{s})$
$\, x$ is the position [length], example $\,m$

Edema

July 26, 2020April 18, 2012 by Anand Bhumkar

Edema;

refers to an accumulation of interstitial fluid to a point where it is palpable or visible.

In general this point is reached with a fluid volume of 2–3 L. Edema formation is the result of a shift of fluid into the interstitial space due to primary disturbances in the hydraulic forces governing transcapillary fluid transport, and of subsequent excessive fluid reabsorption by the kidneys. Deranged capillary hydraulic pressures initiate edema formation in congestive heart failure and liver cirrhosis, whereas a deranged plasma oncotic pressure is leading to edema in nephrotic syndrome and malnutrition. Increased capillary permeability is responsible for edema in inflammation and burns.

Mpharm Practical Lab’s Experiment Manual

July 26, 2020April 17, 2012 by Anand Bhumkar

Experiments for Mpharm Pharmaceutics (Practical record)

This practical manual consists procedures and reports for the following list of experiments:

PREPARATION AND EVALUATION OF SUSTAINED RELEASE MATRIX TABLETS 2
PREPARATION AND EVALUATION OF TRANSDERMAL PATCH OF IBUPROFEN 7
PREPARATION AND EVALUATION OF BUCCAL PATCH 11
VALIDATION OF TABLET COATER 14
VALIDATION OF TABLET PRESS 18
VALIDATION OF LAMINAR AIR FLOW HOOD 24
VALIDATION OF MEMBRANE FILTERS 27
VALIDATION OF HOT-AIR OVEN 30
EFFECT OF PERMEATION ENHANCERS ON DRUG PERMEATION THROUGH BIOLOGICALMEMBRANES 40
VALIDATION OF COATING PAN 42
PREPARATION OF KILLED BACTERIAL VACCINE 50
VALIDATION OF TABLET PUNCHING MACHINE 52
VALIDATION OF ASEPTIC ROOM 58
VALIDATION OF AUTOCLAVE 61
VALIDATION OF TRAY DRYER 64

Download the entire record in pdf here

Novel_Drug_Delivery_Systems_part 2_record

Dropbox – A must for Mpharm students and Research Scholars

July 26, 2020April 17, 2012 by Anand Bhumkar

Dropbox

Dropbox is a free service that lets you bring all your photos, docs, and videos anywhere. This means that any file you save to your Dropbox will automatically save to all your computers, phones and even the Dropbox website.

Dropbox vs Gmail

Dropbox is a file backup service. You may wonder why you want to use a online backup service when you already a Gmail where you can attach all your important files as email. And also Gmail offers a plenty of storage. Then why Dropbox.

Dropbox is Simple

Now to upload something into Gmail you have to open your Gmail, type in the passwords , login, compose mail, attach your files and then save it. But with Dropbox you simply have to save your files in a folder called Dropbox that is next to your “My Documents” folders. Its as simple as saving a file in My Documents Folder.

After you install the software on your computer you just need to register for a username and password and then you are all setup. The files you add to the folder will be backed up when you are connected to the internet. You dont have to do anything. All the backed up files can also be viewed from their website at dropbox.com also. So no more regrets that you forgot your laptop at home Smile

Dropbox is Free

You will get 2.5 GB of Dropbox space for lifetime and its free. Click here

So people its good to save your project work or thesis in dropbox so that even if your computer crashes or is infected with virus, your work is safe.

(P.S. I know how torturous it is when we lose our typed word doc or forget to save it)

With Regards

– Pharmawiki Team

(Dropbox indeed made my project work easier)

Supersaturation

July 26, 2020April 17, 2012 by Anand Bhumkar

The term “supersaturatio” refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under the solubility amount. It can also refer to a vapor of a compound that has a higher (partial) pressure than the vapor pressure of that compound.

Solubility

July 26, 2020April 17, 2012 by Anand Bhumkar

Solubility

Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent.

Ectodermin

July 26, 2020April 16, 2012 by Anand Bhumkar

Ectodermin:

A Ring-type ubiquitin ligase for Smad4, serving as a vital regulator of the transforming growth factor– beta (TGF-beta)/BMP signaling pathway in early embryonic development and cancer.

Mechanism

As Smad4 is the Comediator Smad and facilitates the translocation of the R-Smads into the nucleus, ectodermin forces Smad4 out of the nucleus and promotes its degradation.Through this regulation of the TGF-beta signaling, ectodermin keeps ectoderm cells pluripotent until gastrulation and ensures that ectoderm cells do not undertake mesoderm fate. Ectodermin is also important in reducing TGF-beta/Smad4 induced cytostasis as Ectodermin is expressed in the stem cells of colorectal cancer and intestinal crypts.

Pharmacogenomics (2001): Werner Kalow, Urs A.Meyer, Rachel F. Tyndale

July 26, 2020April 14, 2012 by Anand Bhumkar

Licinio pharmacogenomics the search for individualized therapies

July 26, 2020April 14, 2012 by Anand Bhumkar

Dissolution

Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. For the dissolution of solids, the process of dissolution can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent

The rate of dissolution quantifies the speed of the dissolution process.

The rate of dissolution depends on:

nature of the solvent and solute

temperature (and to a small degree pressure)

degree of undersaturation

presence of mixing

interfacial surface area

presence of inhibitors (e.g., a substance adsorbed on the surface).

The rate of dissolution can be often expressed by the Noyes-Whitney Equation or the Nernst and Brunner equation[1] of the form:

where:

m – amount of dissolved material, kg

t – time, seconds

A – surface area of the interface between the dissolving substance and the solvent, m2

D – diffusion coefficient, m2/s

d – thickness of the boundary layer of the solvent at the surface of the dissolving substance, m

Cs – concentration of the substance on the surface, kg/m3

Cb – concentration of the substance in the bulk of the solvent, kg/m3

For dissolution limited by diffusion, Cs is equal to the solubility of the substance.

Dissolution rates vary by orders of magnitude between different systems. Typically, very low dissolution rates parallel low solubilities, and substances with high solubilities exhibit high dissolution rates, as suggested by the Noyes-Whitney equation. However, this is not a rule.

Fick’s laws of diffusion describe diffusion and can be used to solve for the diffusion coefficient, D. They were derived by Adolf Fick in the year 1855.

where

is the “diffusion flux” [(amount of substance) per unit area per unit time], example . measures the amount of substance that will flow through a small area during a small time interval.

is the diffusion coefficient or diffusivity in dimensions of [length2 time−1], example

(for ideal mixtures) is the concentration in dimensions of [(amount of substance) length−3], example

is the position [length], example

Fick’s second law predicts how diffusion causes the concentration to change with time:

Where

is the concentration in dimensions of [(amount of substance) length−3], example

is time [s]

is the diffusion coefficient in dimensions of [length2 time−1], example

is the position [length], example

Edema;

refers to an accumulation of interstitial fluid to a point where it is palpable or visible.

Experiments for Mpharm Pharmaceutics (Practical record)

PREPARATION AND EVALUATION OF SUSTAINED RELEASE MATRIX TABLETS 2

PREPARATION AND EVALUATION OF TRANSDERMAL PATCH OF IBUPROFEN 7

PREPARATION AND EVALUATION OF BUCCAL PATCH 11

VALIDATION OF TABLET COATER 14

VALIDATION OF TABLET PRESS 18

VALIDATION OF LAMINAR AIR FLOW HOOD 24

VALIDATION OF MEMBRANE FILTERS 27

VALIDATION OF HOT-AIR OVEN 30

EFFECT OF PERMEATION ENHANCERS ON DRUG PERMEATION THROUGH BIOLOGICALMEMBRANES 40

VALIDATION OF COATING PAN 42

PREPARATION OF KILLED BACTERIAL VACCINE 50

VALIDATION OF TABLET PUNCHING MACHINE 52

VALIDATION OF ASEPTIC ROOM 58

VALIDATION OF AUTOCLAVE 61

VALIDATION OF TRAY DRYER 64

Dropbox

Dropbox vs Gmail

Dropbox is Simple

Dropbox is Free

Solubility

Ectodermin:

Mechanism

The rate of dissolution can be often expressed by the Noyes-Whitney Equation or the Nernst and Brunner equation^[1] of the form:

A – surface area of the interface between the dissolving substance and the solvent, m²

D – diffusion coefficient, m²/s

C_s – concentration of the substance on the surface, kg/m³

C_b – concentration of the substance in the bulk of the solvent, kg/m³

For dissolution limited by diffusion, C_s is equal to the solubility of the substance.

$J$ is the “diffusion flux” [(amount of substance) per unit area per unit time], example $(\tfrac{\mathrm{mol}}{ \mathrm m^2\cdot \mathrm s})$ . $J$ measures the amount of substance that will flow through a small area during a small time interval.

$\, D$ is the diffusion coefficient or diffusivity in dimensions of [length² time⁻¹], example $(\tfrac{\mathrm m^2}{\mathrm s})$

$\, \phi$ (for ideal mixtures) is the concentration in dimensions of [(amount of substance) length⁻³], example $(\tfrac\mathrm{mol}{\mathrm m^3})$

$\, x$ is the position [length], example $\,\mathrm m$

$\,\phi$ is the concentration in dimensions of [(amount of substance) length⁻³], example $(\tfrac\mathrm{mol}{m^3})$

$\, t$ is time [s]

$\, D$ is the diffusion coefficient in dimensions of [length² time⁻¹], example $(\tfrac{m^2}{s})$

$\, x$ is the position [length], example $\,m$