5-fluorouracil

Mechanism of action:

5-FU is a cytostatic drug that causes the inhibition of the formation of DNA through the inhibition of Thymidylate synthesis. [1]

Uses of 5-Fluorouracil (5-FU):

It is used as an anti-cancer agent and anti-scarring agent. [1]

References:

[1] New concept in glaucoma treatment by Faezah Sarfarazi. United States Patent, 5304561.

Further Reading:

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Vesicles

Introduction:
Small packets or bubbles that are used for the transport of materials within a cell and across the cell membrane.

Classification of Vesicles:
We can classify the vesicles on the following factors:
1. Structure
2. Liposomal preparation
1. Classification on the basis of structure
There are following types of vesicles on the basis of structure:

a. Small unilamellar vesicles; abbreviated as SUV. Size ranges from 20-100 nanometer.
b. Medium sized unilamellar vesicles; abbreviated as MUV.
c. Large unilamellar vesicles; abbreviated as LUV. Size is greater than 100 nanometer.
d. Oligolamellar vesicles; abbreviated as OLV. Size ranges from 0.1-1 micrometer.
e. Multilamellar large vesicles; abbreviated as MLV. Size is greater than 0.5 micrometer.
f. Giant unilamellar vesicles; abbreviated as GUV. Size is greater than 1 micrometer.
g. Unilamellar vesicles; abbreviated as UV. All size range.
h. Multivesicular vesicles; abbreviated as MVV. Size is large, usually greater than 1 micrometer.

2. Classification on the basis of liposomal preparations

There are following types of vesicles on the basis of liposomal preparations:
 a. Vesicles made by reverse phase evaporation method:
      i. Oligolamellar vesicles (also known as single vesicles); abbreviated as REV
      ii. Multilamellar vesicles ; abbreviated as MLV-REV
 b. Stable plurilamellar vesicles; SPLV
 c. Vesicles prepared by extrusion methods; abbreviated as VET
 d. Frozen and thawed multilamellar vesicles; abbreviated as FATMLV

 e. Dehydration-rehydration vesicles; abbreviated as DRV

Lamella

A thin layer of tissue.

Unilamellar

Having a single layer of lamella.

Sphingosomes and sphingolipids

Sphingosomes are similar in structure to liposomes but in sphingosomes, lipids namely sphingolipids are responsible for making up the bilayer of sphingosomes.

Figure: Sphingolipids

(Murray S. Webb et al.) The formulations have enhanced stability and thus are used in methods for improved drug delivery and effective treatment.

Sphingolipids:
They belong to a class of lipids i.e. Membrane lipids. Sphingolipids come from the combination of sphingosine (a long chain base), which is an amino alcohol (and aliphatic in nature), and fatty acid.It is the simplest sphingolipid and is also referred to as sphingoid base. They have a head, which is polar in nature, and two tails, which are nonpolar.

The following mnemonic will help you a lot in remembering the structure of shingosine.

Sphingolipids are present in plasma membranes.

Types of sphingolipids:

1. Ceramide:
It consists of Fatty acid chain and sphingosine linked through amide linkage. It is ordinarily present in all sphingolipids.

These are the precursors of glycolipids and phospholipids having a wide range of function in the tissues.

2. Sphingophosphlipids
    a. Sphingomyelin
    It consists of Phosphoethanolamine or phosphocholine and 1-hydroxy group of a ceramide linked through ester linkage.Sphingomyelin is structurally similar to phosphatidylcholine but biologically and physically it is different.

3. Glycosphingolipids:
     a. Cerebrosides
     b. Sulfatides (Sulfated cerebrosides)
     c. Globosides
     d. Gangliosides

Synthesis of sphingolipids:
Synthesis of sphingolipids takes place in Endoplasmic reticulum. Following is the pathway for the synthesis of sphingolipids.

In the first step, Palmitoyl-CoA alongwith serine results into beta ketosphinganine to sphinganine to N-acylsphinganine to Ceramide containing sphingosine to Cerebroside and sphingomyelin.

Sphingomyelin cycle:
Sphingomyelin cycle is used to show a relationship between the metabolic products of sphingolipids.

Free sphingosine and certain other long chain bases work as mediators for many of the cellular processes. Sphingosine 1-phosphate and ceramide 1-phosphate increases mitosis.

Degradation of sphingolipids:
These are degraded by lysosomal enzymes.

Presence of sphingolipids in Micro-organisms:
Sphingolipids are also found in some genera of bacteria like sphingomonas and sphingobacterium.

Uses of sphingolipids:
They work as the site of adhesion of extracellular proteins. Sphingolipids are important in cell recognition and signal transmission/transduction.
Sphingolipids form the myelin sheath around the nerves in central nervous system.

Diseases in which sphingolipids are involved:
1. Microbial infections
2. Diabetes
3. Alzheimer's disease
4. Certain cancers
5. Some diseases of the respiratory and cardiovascular systems and
6. Some of the neurological syndromes

References:
Murray S. Webb, Marcel B. Bally, Lawrence D. Mayer, James J. Miller, Paul G. Tardi, Sphingosomes for enhanced drug delivery. Patent number: 5814335.

Further Reading:
Delivery System Handbook for Personal Care and Cosmetic Products : Technology, Applications and Formulations (Breakthroughs in Personal Care and Cosmetic Technology) by Meyer R. Rosen

Encyclopedia of Pharmaceutical Technology by James Swarbrick

Hannun, Y. A. 1994. The sphingomyelin cycle and the second messenger function of ceramide. Journal of Biological Chemistry, Vol. 269, No. 5.

http://lipidlibrary.aocs.org/lipids/introsph/index.htm

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Industrial Pharmacy

Industrial is the part of Pharmacy in relation to the manufacturing and Quality control of Pharmaceutical products which include a diverse range of items. It is different from Hospital Pharmacy in that Hospital Pharmacist is in direct contact with patient. he has to examine the patient medication history and is well aware of pharmacology. On the other hand, Industrial pharmacist is well aware of how a product is to be prepared. He has good knowledge of pharmaceutics.

Further Reading:
The Theory and Practice of Industrial Pharmacy by Leon Lachman, Joseph L. Kanig and Herbert A. Lieberman

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Retail Pharmacy

Retail Pharmacy is the place where there is the sale of Medicines (health related products and in some cases other items of daily use) directly to the customers (consumers).

Further Reading:
Marketing and retail Pharmacy by Colin Gilligan, Robin Lowe and Peter Cattee

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