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Development of Controlled Drug Delivery Systems (CDDS)

1. 1 Managed Medication DELIVERY SYSTEMS (CDDS)

Now a day's on the introduction of Novel drug delivery systems (NDDS) designated consideration has been targeted. The method of drug delivery to the site of action shows a substantial influence on its efficiency. It leads to the development and evolution of novel medicine delivery systems that increased performance of potential drug molecules. Novel medication delivery systems play a key role in pharmaceutical research and development. Since when compared new chemical moiety the developmental cost and time necessary for adding NDDS is relatively low.

Oral way remains one of the most 'natural' routes of drug administration and has seen exceptional accomplishments in the last couple of ages towards marketing of oral delivery of medication molecules. Dental ingestion is one of the oldest and most extensively used routes of drug administration. They offer an effective approach to obtaining systemic and local results.

Drug delivery describes a process whereby a healing agent is given to the body in a handled manner. The product's commercial and medical value, product differentiation can be improved upon by developed drug delivery systems. These advanced technology serve as a sophisticated resource to outreach your competition. By simplifying the supervision and dosing regimen medicine delivery technology make medication more suitable and convenient to an individual.

Any medication molecule by using Novel medication delivery system (NDDS) can get a 'new life, ' and thus improving the competitiveness, patent life and market value. Among different NDDS present in the marketplace, the major talk about on the market is keep by the dental controlled release systems due to its greater great things about patient conformity and ease of administration. The introduction of book and highly functional delivery systems and osmotic medicine delivery systems will be the major contribution in oral NDDS.

Basically, there are three novel methods of medicine delivery, i. e.

  1. Targeted delivery,
  2. Modulated release and
  3. Controlled release.

Targeted delivery refers to the administration of any medicine carrier systemically to be able to deliver medicine to the precise type of skin cells, tissue or organs. Modulated release signifies use of a medication delivery device that emits the medication under managed environmental conditions, bio reviews, sensor insight or an external control device at a varying rate. Controlled release identifies a specific device that offers the medication at specific release profiles or at a predetermined rate in to the patient body.

1. 1 Governed Medication DELIVERY SYSTEMS (CDDS)

The nature of the managed release dose form is in a way that the release is determined by the look of the machine and the physiochemical properties of the medicine and is in addition to the external factors or the microenvironment in which the dosage form is placed. The products typically provide significant benefits over immediate-release regular dosage formulations. Maximum therapy with recurring administration of conventional dosage varieties (e. g. injectables, liquids or tablets) can classically be pursued by dosage scheduling. The aim of this technique is to maintain drug concentration in a healing range, above the minimum effective focus and below the dangerous concentration.

Thus CDDS avoids the undesired saw teeth characteristics of the plasma focus vs time profiles of the traditional medicine products.

A diagrammatic illustration of manipulated versus conventional dose delivery is shown in Body-1.

Fig 1. 1 Plasma & Time profile of controlled medication release and standard release

The plasma focus of the medicine extends to a maximum (crest) with regular dosage forms and then lower (trough) at the stage where repeated administrations is needed to keep the plasma medicine concentration. Frequently the initial focus is above the therapeutically effective level which could increase the threat of side effects. Normal dosage varieties can thus bring about a drug strategy where the drug concentration oscillates between alternating intervals of overdose and inefficiency.

The delivery of drug at handled rate over an extended time period is represented mathematically:

Rate in = Rate out = Ke x Disc x Vd

Where Disc is the required medicine level, Vd is the quantity of distribution and Ke rate content for drug elimination from the body.

Added to the, the high cost of development of new, safe, specific and effective medicine molecule is prohibitive and expanding nations nearly cannot afford such included multi-group cost intensive drug development ventures. Therefore, many pharmaceutical companies and drug research institute focused their efforts to build up pre-programmed unattended delivery of medication at a level and for a period to meet and achieve the restorative need. These systems are coined as Governed drug delivery systems

Table 1. 1 Classification of dental handled release systems depending on system of

Release 3 (vyas etal, 2002)



Diffusion Controlled

Reservoir system

Diffusion via a membrane

Monolithic system

Diffusion through the matrix

Water permeation controlled

Osmotic systems

Osmotic transportation of water through the semi permeable membrane

Swelling systems

Water penetration into a glassy polymer

Chemically Controlled

Monolithic system

Either natural polymer erosion (surface erosion) or a mixture oferosion and diffusion(bulk erosion)

Pendent system

Combination of hydrolysis of the pendent group and diffusion from the bulk polymer

Ion exchange resin

Exchange of acidic or basic drugs with ions present on resins

Regulated systems

Magnetic, Ultrasound


External application of magnetic field or ultrasound device

Use of competitive desorption or enzyme substrate reactions. Rate control is made in to the device



As manipulated release dose form are just a little expensive than standard formulations, they cannot be justified unless they feature come scientific or practical advantages given below:

  • Reduction in dosing frequency
  • More even effect
  • Reduced fluctuation in constant levels
  • Increased security margin of high strength drugs
  • Improved patient convenience and compliance
  • Reduced in total amount of medication dosage administered
  • Avoidance of night time dosing
  • Reducing of GI irritation and other dosage related side effects and
  • Reduction in healthcare cost.


However, controlled medicine delivery systems likewise have some drawbacks. They include,

  • High cost;
  • Poor systemic availableness;
  • Unpredictable and often poor invitro-invivo relationship;
  • Possibility of dosage dumping;
  • Dosage adjustments probable is reduced;
  • First move clearance probable is increased;
  • In circumstance of hypersensitivity reactions, toxicity or poisoning medication retrieval is difficult;
  • Effect of oral dose depends upon Mean Property Time.

To control or change the medication release from a dosage form there will be a number of design options. A lot of the per oral manipulated release dosage varieties comes under the group of osmotic, matrix or tank systems. The polymer matrix is made up of embedded medicine in matrix systems where the release occurs by partitioning of drug in to the release medium and polymer matrix. In case of reservoir systems a rate managing membrane is surrounded and covered around the medication core. But, drug release from conventional managed systems i. e. , tank and matrix systems is damaged by various factors like existence of food, pH and various physiological factors. In case there is osmotic systems the medication is delivered predicated on the ideas of osmotic pressure. The medicine release from this system doesn't be based upon the pH and different physiological parameters and therefore by optimizing the drug and systems properties the release characteristics can be modulated.



In 1955 Rose and Nelson employed the guidelines of osmotic pressure in drug delivery for the first time. They defined two systems; the one which sent 0. 02 ml/day for 100 days and nights and another that sent 0. 5 ml/day for 4 days and nights, both for use in Pharmacological research.

In the 1970s, Higuchi and Leeper suggested some variations of the Rose-Nelson pump5. Theeuwes further modified the Rose-Nelson pump and developed something. Small osmotic pumps of these forms are sold under the trade name ALZET (Alza Corp. , CA). These devices has a volume of approximately 170l, and the normal delivery rate is 1l/hr.

A major milestone was achieved in 1974 with the information by Theeuwes and Alza's co-workers of your tablet design composed of a compressed tablet-core surrounded by a semi permeable membrane with a single orifice, so-called Elementary osmotic pump (EOP). This design adaptation for human being use was ideally processable using standard tabletting and layer procedures and equipment. The first two products indomethacin, Osmosin6 and phenylpropanolamine, Acutrim TM6 were launched in the 1980s.

Oral osmotic drug delivery system (OODS) development continuing with two new OODS designs, the controlled-porosity osmotic pumps (CPOP) and the push-pull osmotic pumps (PPOP). The to begin these was the CPOP, which was designed to decrease the risk of extremely localized drug-induced soreness at the site near to the orifice.

In the 2000s, a fresh drug product predicated on OODS technology was formulated to deliver methylphenidate to children (above the age of 6 years) with attention-deficit hyperactivity disorder (ADHD). These delivery systems were based on a new design, the push-stick osmotic pumps (PSOP), which mixed immediate and sustained drug release phases.

The medicine release out of this system doesn't depend on the pH and different physiological parameters and so by optimizing the drug and systems properties the discharge characteristics can be modulated. Within the last couple of years more variety of patents are awarded on these oral omotic medicine delivery systems. These systems has ability to improve restorative agents clinical account and so they are becoming one of the most attractive technologies today.

Osmotically controlled dental medicine delivery system for the controlled delivery of effective agents employs osmotic pressure principle. For the manipulated medication delivery osmotic devices are most assured strategy based mostly systems. On the list of controlled medication delivery systems they are most reliable systems. Osmotic systems could be used in the form of implantable devices or dental drug delivery systems. Osmotic pump tablet (OPT) generally contains a core like the medication, an osmotic agent, other excipients and semi-permeable membrane cover.

1. 2. 2. THEORY

Osmosis can be defined as spontaneous movement of a solvent from a solution of lower solute attention to a solution of higher solute concentration through an excellent semi permeable membrane, which is permeable only to the solvent and impermeable to solute. The pressure put on the higher-concentration aspect to inhibit solvent movement is named osmotic pressure8.

Osmotic pressure is a colligative property, which depends on attentiveness of solute that contributes to osmotic pressure. Solutions of different concentrations having the same solute and solvent system display an osmotic pressure proportional to their concentrations. Thus a regular osmotic pressure, and in doing so a constant influx of normal water can be achieved by an osmotic delivery system that results in a continuous zero order release rate of medication8.


An osmotic system releases a therapeutic agent at a predetermined, zero order delivery rate predicated on the basic principle of Osmosis, which is motion of an solvent from lower concentration of solute towards higher awareness of solute across a semi-permeable membrane.

When osmotic system is administered, from the main one or more delivery plug-ins the drug which contain suspension or solutions is pumped out of the core due to the hydrostatic pressure produced by the imbibition of normal water in to the key osmotically through the semi-permeable membrane. From the water influx through semi-permeable membrane the delivery of medicine out of this system can be managed.

Osmotic pressure is directly proportional to temps and concentration and the following equation details the relation between them:

О  = ˜cRT


OP = osmotic pressure,

О  = osmotic coefficient,

c = molar focus,

R = gas constant,

T = Absolute temperature.


Osmotic pump is a new delivery device, which delivers drugs or other effective brokers at a handled rate by the rule of osmosis. Control resides in the water permeation properties of the formulations

Table: 1. 2 Types of some marketed music group of Osmotic drug delivery system7


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