Control Release Dosage Form CRDF Biology Essay

Control release dose signifier ( CRDF ) is the one which delivers the curative agents at a preset rate for a specified period of clip.

The basic rule behind the coevals of controlled release dose is to modify the pharmacokinetic and pharmacodynamic belongingss of a drug in such a manner that which help to better public-service corporation of a drug by maximal lessening in side effects and remedy or command the disease in shortest period of clip by utilizing really less measure of drug administered by most easy manner.

CRDF maintain drug plasma level between a maximal safe degree and minimal effectual degree over the long period of clip. Thus it is safe and besides helps to cut down the frequence of drug disposal. Merchandises of this type have been formulated for unwritten, injectable and topical usage. [ 1 ]

Categorization of CRDF

Depending upon the mode of drug release and methods of readying, these systems can be classified into following three chief types –

1 ] Physical Systems:

( I ) Diffusion-controlled systems

( A ) Massive systems

– Dissolved drug

– Dispersed drug

– Porous system

– Hydrogel

– Biodegradable

( B ) Reservoir System

– Constant activity

– Non-constant activity

– Unsteady-state

( II ) Ion exchange rosin system

( III ) Osmotically controlled systems

– Micro porous osmotic pumps

– Push / pull systems

( IV ) Hydrodynamically balanced systems

( V ) Other physical systems ( geometry )

2 ] Chemical Systems:

( I ) Immobilization of drugs

( II ) Prodrugs

3 ] Biological Systems:

( I ) Gene Therapy [ 2 ]

Mechanism of Action of CRDF

The treatment of current undertaking was limited merely to oral controlled release preparations. These preparations are devices or dose signifiers that controls the release of drug at the site of soaking up.

The mechanism of controlled release is governed by following systems –

I. Diffusion controlled release

II. Chemically controlled release

III. Osmotically controlled release

IV. Barrier surfacing controlled release

V. Prodrugs.

Two types of diffusion controlled release systems are available. The first 1 is Matrix system and other one is Reservoir system. Current undertaking was based on diffusion controlled release by Matrix system. In this system drug is homogeneously assorted with polymer either as microsphere conventional tablets or as nanosphere. When these systems come in contact with the medium ( organic structure fluid ) , the drug is released by diffusion mechanism. Here cross-linking denseness plays a critical function and is frequently utilised to command the release word picture. [ 3 ]

Applications of CRDF

It is used when traditional injectable and unwritten dose signifiers can non be utile. Uses include –

Drug bringing to specific sites.

Drug bringing at controlled rate.

Delivery of two or more agents with individual preparation.

Advantages of CRDF

Improved patient conformity by cut downing frequence of drug disposal.

Maximal use of drug.

More unvarying pharmacological consequence.

Decrease in fluctuation in blood plasma degree.

Remarkable decrease in side effects.

Disadvantages of CRDF

Poor in vitro – in vivo correlativity.

Reduced flexibleness in seting dose regimen for doctors because it is already fixed by the dose signifier design.

This signifier is non utile if the drug is holding narrow curative index.

Expensive preparation. [ 4 ]


Trade Names- fusidin, fusiwal, fusigen

Structure –

Chemical Name –

16 – ( Acetyloxy ) -3, 11-dihydroxy-29-normmara-17 ( 20 ) , 24-dien-21-oic acid Na salt.

Molecular Formula –


Molecular Weight – 538.70

Category – It belongs to Antibacterial category. [ 5 ]

General Description –

It is a Sodium salt of fusidic acid which was obtained from a strain of the fungus Fusidium coccineum. [ 6 ] It is steroidal antibiotic from antibacterial category and it is extremely active against most of the gm positive bacteriums like Streptococci, Staphylococci and Corynebacteria. Sodium Fusidate is inactive against most of the gm negative bacteriums.

Use –

It is used for the intervention of bone and joint infections. Besides it is used in infections of tegument and soft tissues.

Actions –

Pharmacological and pharmacokinetics.

Mechanism of Action –

Sodium Fusidate inhibits bacterial protein synthesis by interfering with amino acid transfer from aminoacyl- transfer RNA to protein on ribosomes. It shows bacteriostatic and/or disinfectant action.

Absorption –

It is really good absorbed orally. Oral tablets have about 91 % bioavailability.

Protein Binding –

It shows extended protein binding ( 97-99 % ) .

Distribution –

Drug is good distributed.

Metabolism –

It includes H fusidic acid, dicarboxylic ester/acid, 3-keto fusidic assistance, glycol metabolite and a glucuronide fusidic acid.

Excretion –

Metabolic merchandises excreted in gall. Minimal elimination through piss. Fusidic acid is excreted through fecal matters ( 20 % ) .

Side effects –

It shows GI piece of land perturbations, particularly icterus, thrombophlebitis or venospasm.

Storage –

It should be stored in a temperature between 15 to 250 C. [ 7 ]


Structure –

The figure and sequence of Mannwrolate and Glucuronate residues ( as shown above ) vary in the of course happening alginate.

Molecular Formula – ( C6H7NaO6 ) n [ 8 ]

Structure of an alginic acid is rather complex and it forms a H2O soluble salt by replacing some of the H molecules by Na of the carboxyl groups. [ 9 ]

General Description –

Sodium alginate is a of course happening polymer. It is a sodium salt of an alginic acid which is derived from selected assortments of natural brown sea weed, besides known as algae.

Traditionally it is obtain as a pink coloring material pulverization. It has a batch like smell which is helpful for its usage as a dental stuff. Sodium alginate signifiers a soluble alginate with H2O.

Puting Process –

For a good scene, correct blending ratio of a Na alginate and H2O is really indispensable. … … … … … … … … … … … .

Sodium alginate is a additive polymer and when it is assorted with H2O it forms a soluble alginate by spread molecules in H2O which reacts with Ca salts. This manner polymerization occurs by cross-linking of ironss. These molecules attach with each other to organize a web of filaments which encloses H2O and other byproducts. Concluding construction is looks like a gel.

Strength of the gel depends on following factors –

Strength of the gel is straight relative to the figure of filaments.

Correct blending method is critical for proper strength of the gel.

Gel gets weak if mixing clip is long.

Powder and H2O ratio.

Normally at room temperature gelation clip is 3-4 proceedingss but at mouth temperature, which is 370 C, the scene procedure is small speedy. [ 10 ]

Applications –

For feeling stuff in dental industry.

In nutrient Industry it plays various function, like, it is used for gelling, inspissating, stabilising and movie forming belongingss.

As inspissating agent in dyeing and publishing industry. [ 11 ]


High Performance Liquid Chromatography ( HPLC ) was earlier known as High Pressure Liquid Chromatography. HPLC is a technique for the separation of many compounds. It is most widely used analytical separation technique than any other technique because of its high sensitiveness and speedy response. It is used for accurate quantitative finding ; it is applicable for dividing volatile and non volatile stuffs. HPLC sensors can work continuously and can observe really little sums. It has widespread pertinence to the substances that are of premier involvement to industry and to the many Fieldss of scientific discipline. Such stuffs include aminic acids, antibiotics, steroids, drugs, nucleic acids, hydrocarbons, proteins, metals, organic species and most of the inorganic substances.

Principle –

The rule of HPLC lies around the general rule of chromatography. The separation of compounds is achieved with regard to the clip spent by the constituent in liquid stationary stage. The equilibrium between the constituent and stationary stage occurs by surface assimilation, partitioning or by ion exchange.

Resolution is the effectual separation of constituents from its mixture into distinct set. The deciding power of chromatographic column is straight relative to length of theoretical home bases and reciprocally relative to the tallness of the theoretical home base.

The relation is given by the undermentioned equation –

N = L / H

Where, N = figure f theoretical home bases

L = Length of chromatographic column

H = Height of theoretical home base

Theoretical home base is the topographic point where the sample is in equilibrium with stationary stage and nomadic stage. The stationary stage in HPLC refers to the solid support contained within the column over which the Mobile stage flows continuously. The nomadic stage in HPLC is the solvent being continuously applied to the column. It is a bearer for the sample solution. [ 12, 13 ]

HPLC Techniques –

I ] Based on Modes of Chromatography

Normal stage manner

Rearward stage manner

II ] Based on Separation Principle

Ion Exchange chromatography

Ion brace chromatography

Adsorption chromatography

Gel pervasion or Gel filtration chromatography

Chiral stage chromatography

III ] Based on Scale Operation

Analytic HPLC

Preparatory HPLC

IV ] Based on Elution Technique

Isocratic separation

Gradient separation

V ] Based on Type of Analysis

Qualitative analysis

Quantitative analysis

Types of HPLC Instrument –

I ] Mobile stage reservoirs:

It is made up of a glass or chromium steel steel which contains 200 to 1000 milliliter of a dissolver. To take the dissolved gases normally oxygen and N, reservoirs are frequently equipped with degassers.

II ] Pumping system:

Introduction of pumping system in HPLC is an built-in facet for speedy separation. It should bring forth high force per unit area and maintain changeless flow of the dissolver through the columns. The of import characteristics of an ideal pumping system are –

It should bring forth force per unit area up to 6000 pounds per square inch.

It gives pulse-free end product.

Keep a changeless flow rate of dissolver in between 0.1 to 10 ml/min.

Three types of pumps are used for HPLC.

Reciprocating pumps –

It is most normally used pump in commercial available HPLC system due to its God belongingss. In reciprocating pump dissolver is hold in a little chamber and pumped by the dorsum and Forth gesture of a motor-driven Piston. The advantages related to these pumps include their changeless flow rates, high end product force per unit area and little internal volume which hold little volume of dissolver. Merely one disadvantage is that it produces a pulsed flow. The pulsed flow cause unstable baseline and addition in noise. To understate the pulsed flow pulsation moistener is used.

Displacement pump –

It is a big syringe like chamber. It displaces a fixed volume of dissolver from pump to the column by a speculator driven by motor. It produces pulse free end product. The disadvantage related to this pump system is that it has limited sum of sample capacity and is inconvenient when dissolver alteration is necessary.

Pneumatic pump –

In these pumps solvent or nomadic stage is held in a collapsable container. The nomadic stage is forced out with changeless force per unit area when force per unit area is applied by a tight gas. The advantage related to these pumps is they are cheap and produces pulse free flow. It has disadvantage of limited dissolver capacity and utile merely when force per unit area is below 2000 pounds per square inch.

III ] Sample injection system:

Introduction of accurate volume of sample is important for better preciseness of the liquid chromatographic measurings because overloading of the sample causes set broadening. In HPLC sample debut is done either by trying cringle or by car sampling station.

( figure )

Sample loop –

This sample injection system is used for manual manner operation. The sample cringle is rotated and the sample is assorted with nomadic stage. Then without any perturbation in the flow rate this sample is introduced into the column. By sample loop debut of the really less volume of sample is besides possible like 0.5 to 5µl.

Auto sampling station –

This injection system is utile for big figure of samples. This is besides reduces the human mistake during trying. In an car sampling station samples are arranged either in handbill or rectangular manner.

IV ] Chromatographic column:

Analytic columns –

It is an indispensable portion of a HPLC system. The HPLC columns are available in assorted sizes and packing. Normally the analytical columns used in HPLC are 10-30 centimeter in length and 4-10mm in internal diameter. The most common atom size for column wadding is 5 or 10µm.

Guard column –

Normally this column is introduced before the analytical column. Guard column is used to forestall analytical column from contaminations and particulate affair in dissolvers. Therefore it helps to increase the life of expensive analytical column.

Types of column waddings –

Porous – It is consist of porous microparticles holding diameter runing from 3 to 10µm. Microparticles are by and large composed of silica ion-exchange rosin R an aluminum oxide.

Pellicular – It contains not porous, spherical, glass or polymer beads with typical diameter of 30 Ts 40 µm. A thin bed of silicon oxide or an ion exchange rosin is deposited on these atoms. Now yearss these type of waddings are used normally for guard columns non for analytical columns.

V ] Detectors:

High sensitiveness and stableness of the sensor system in HPLC is important due to measure of stuff applied to the column is often really little.

Features of an ideal HPLC sensor are –

God stableness and duplicability.

Have a response that increase linearly with the sum of solute.

Have high sensitiveness and predictable response.

High dependability and easy to utilize.

Similarity in response to all solutes.

Non-destructive of the solute.

Not contribute t extra-column extremum widening.

Types of sensors: –

HPLC sensors are classified in to two basic types.

Bulk Property sensors – These sensors respond to a bulk belongings of nomadic stage like refractile index, dielectric invariable or denseness.

Solute Property sensors – These types of sensors responds to some belongingss of solute such as UV optical density, fluorescence or diffusion current.

Normally used HPLC sensors –

Ultraviolet Absorbance sensors

Fluorescence sensors

Infra-red optical density sensors.

Refractive-index sensors

Evaporative visible radiation dispersing sensors.

Electrochemical sensors.

From all above sensors one of the most normally used sensors is UV optical density sensor. It is really simple sensor. Mercury lamp used as a beginning in UV soaking up sensors. This sensor is restricted to solutes which can absorb the wavelengths 250 nanometers, 313 nanometer, 334 nanometer and 365 nanometer. Speciess flows from the column detected by Deuterium or tungsten fibril. The modern instrument by and large contains filter wheels which detect assorted species quickly as they are eluted. Some of the UV soaking up sensors use monochromators.

Application of HPLC –

HPLC system shows huge applications in assorted Fieldss like pharmaceutical, environmental and biochemical due to its high velocity, better declaration and sensitiveness.

Quality of the concluding merchandise in most pharmaceutical industries is checked by utilizing HPLC system.

In nutrient industry it is used for residuary testing of contaminations.

In the field of biochemistry mixture of amino acid is separated and qualitatively determined by utilizing HPLC.

In chemical and biomedical research it is used to analyze the complex mixture.

Particularly rearward stage divider HPLC is utile for the separation of drugs and their metabolites, peptides, steroids, polyphenols and vitamins.

HPLC is used for standardization of criterions and to find release profile of drugs. [ 12,13 ]




Chemical and reagents used in the present undertaking are as follows –



Sodium alginate

Kent Express.

Sodium Fusidate

Sigma-Aldrich, UK.


Fisher Scientific, UK.

Orthophosphoric acid

Fisher Scientific, UK.

Deionised H2O

Made in HPLC research lab.

Table: List of chemical and dissolvers used

2.2 Instrumentality:

HPLC Instrument –

Agilent 1200 Series liquid chromatography system.

It is an isocratic system with a manual sampling station.

G1365D multiwavelength sensor with DE64255278 consecutive figure.

Microvaccum degasser with quaternate pump.

Analytic Balance –

Mettler Toledo AB 104-S/FACT

Syring –

20µl manufactured by SGE Ltd. , Australia.

Column –

Number: 00F-3033-EO


Size: 150 x 4.60 mm internal diameter, 5 micrometer atom size

Consecutive figure: 81675

Beakers –

Volume: 50 milliliter and 100 milliliter.

Volumetric flask

Hot Air Oven

Glass Slides

Silicon Rubber Moulds



Weighing Boat


Filtration kit

Small plastic containers

Ceramic tile

2.3 Procedures:

Preparation of Mobile Phase ( 1000 milliliter ) –

Mobile stage contains methanol 800 milliliter, 0.01 M Orthophosphoric acid and 200 milliliters deionised H2O.

0.01 m Orthophosphoric acid was made by adding 0.2 ml Orthophosphoric acid in to 200 milliliter of deionised H2O. Then this H2O was assorted with 800 milliliters methyl alcohol. All the dissolvers were of HPLC class ( e.g. Fisher Supplier UK ) and the blended nomadic stage degassed earlier usage to avoid air bubbles.

Preparation of Standard stock solution –

Accurately weighed 100 milligram of Na Fusidate on a four digit analytical balance transferred carefully into 100 milliliters volumetric flask and made up volume with deionised H2O. This attendant solution is known as standard stock solution which contains Na Fusidate 1000µg/ml. From this solution consecutive dilutions were made.

Formula used to do dilutions is –

C1V1 = C2V2

Where, C1 = concentration of stock solution.

C2 = concentration of dilution to be prepared.

V1 = Volume of unknown concentration to be calculated.

V2 = Volume of volumetric flask in which dilutions were made.

Volume of stock solution

Used ( milliliter )

Deionised H2O ( do up volume ) milliliter


( µg/ml )



















Table: Dilution tabular array

For standardization of the criterion, above prepared dilution were analysed by utilizing HPLC system. The standard standardization curve for Na Fusidate was obtained by plotting concentration on X- axis and peak country on Y- axis.

Experimental conditions –

Flow rate should be 2ml/min.

Detection wavelength – 235 nanometer.

Column used – KROMASIL 50C18 00F-3033-EO

Mobile stage – Following solutions were prepared and degassed

Methanol ( 500 milliliter ) , deionised H2O ( 200 milliliter ) , Orthophosphoric acid ( 0.2 milliliter )

Experimental Procedure –

First prepared nomadic stage was degassed by utilizing degasser. Then it was transferred to mobile stage container and waste roll uping bottle was emptied before turning the instrument on.

HPLC was turned on by exchanging on the pump, sensor and sampling station. An Aglient online procedure was turned on. This has allowed HPLC system working online or offline. This means it has given us flexibleness to redact informations or chromatographic conditions.