About author :
Jony Mallik*, Abdullah Al Faruq
Department of Pharmacy,
Southern University Bangladesh, Chittagong, Bangladesh
Drug delivery is a very important question regards to pharmaceutical drug dosage form. Depending on the delivery principles, drug- products may be categorized into different groups. In immediate release drug products, the release & delivery achieved just after administration to provide available drug level at blood region. Now days, to treat the chronic disorders or to control the release of active principles from drug- products, a very special delivery system included to drug delivery technique. It’s Controlled – Release Drug Delivery System of Novel drug delivery. Most of the active pharmaceutical ingredient(s) are dispensed in the form of CRDDS. For this special delivery system of drug, a very close & well understood profile of manufacturing required. Today it’s a challenge to the pharmaceutical industry to manufacture CRDDS with a reasonable dosage form that possess all the criteria of CRDDS.
Key words: Controlled Release Drug Delivery System (CRDDS), Novel drug delivery, Drug dosage form, Drug delivery, Drug release.
CONTROLLED – RELEASE DDS
Controlled drug delivery system (CRDDS) is a very potential & reliable form of Novel drug delivery technique in which drug is subjected to a suitable pharmaceutical drug dosage form & the release of them is predetermined so that the release controlled at particular site of action (cells , tissues , organs).
Important Features about CRDDS
Rate of drug release is controlled at target site.
Drug released at a constant rate hence steady – state plasma concentration maintained.
Drug release profile is predictable & reproducible.
Drug release obey slow zero-order kinetics.
All CRDDS are Sustained – release DDS (SRDDS).
The unique things regards to CRDDS is polymer used in their formulation. Polymeric membrane or matrix plays a very vital role in releasing medicaments with a desired rate.
COMMON POLYMERS USED IN CRDDS
1. Water soluble polymers
Methyl cellulose (MC)
Sodium carboxymethylcellulose (Sod.CMC)
Hydroxypropyl methylcellulose (HPMC)
Polyvinyl pyrrolidone (PVP)
2. Water insoluble inert polymers
Ethyl cellulose (EC)
Polyvinyl chloride (PVC)
Acrylic acid copolymers
3. Water insoluble enerodible polymers
Paraffin was (Hard & Liquid)
High molecular weight polyethylene glycol (PEG)
Mono /Di / Tri- glycerides
Polyvinyl alcohol (PVA)
Ethylvinyl alcohol & copolymers
Usually drug remains in a reservoir that enclosed by suitable polymeric membrane (rate controlling) . For a better delivery of the active principles , drug are designed to such a system so that it could release its medicaments with a predetermined rate. Most common designs are-
Fat-wax barrier technique
Dialysis membrane technique
Enteric copolymeric technique
Matrix tablet (Plastic , Hydrophillic)
A better design in delivery technique may achieved by issuing any one of the following drug delivery system during manufacturing
A. Rate pre-programmed DDS
B. Activation modulated DDS
C. Feed- Back Regulated DDS
These three has several distinct subtypes. Among them anyone could be used in delivering the active medicaments with a suitable manner. In every cases , the release kinetics maintenance is an important things. The Rate pre-programmed DDS is the technique of choice as for controlled release of drugs from dosage form.
Polymeric Membrane Permeation Control DDS
Specially the polymeric membrane permeation control system is widely used under Rate pre-programmed DDS where drug is either partially or entirely enclosed and remains within a reservoir surrounded by a membrane of selective permeability. Drug molecule will release from their via permeation.
Common examples are: Progestasert (IUD) ,Norplant (Sub-dermal implant) , Ocusert , Transderm Nitro.
Polymeric Matrix Diffusion Control DDS
To achieve controlled release, drug may suspend in a suitable polymeric matrix from where the moieties will release via diffusion process. Drug release obey the following equation
Q/T = (2ACrDp)¹/²
Except these above, there are several DDS used to deliver the drugs at predetermined rate to the target site such as-
Osmotic pressure activated DDS
pH activated DDS
Ion activated DDS
Enzyme activated DDS
Bioerosion regulated DDS
Traditionally, controlled release systems tended to be “second-generation products, building on accumulated clinical experience. However, better awareness of the molecular biology of drug action and the promise of biomarkers and personalized medicine may mean that optimizing performance by controlling release may become a first option in new product development. Such optimization may well help reduce the alarming attrition rates that are now prevalent in new drug development. It is essential text for students, researchers and industrial engineering, formulation and manufacturing technologists as well as quality testing and control functions. In manufacturing time , manufacturer should remember that the CRDDSW has some potential problems such as dose dumping , drug withdrawal difficulties etc.