period of time until the disease persists. Therefore, there is a need of a capable and
effective drug delivery system that can provide the drug on specific time in required
dosage at a given site. Nowadays, membrane separation processes are used for the
development of an efficient and effective drug delivery system [1–3]. Mainly, there
are two types of membrane systems based on the mechanism of drug delivery,
namely, diffusion and osmotic drug delivery systems. These membrane-based drug
delivery systems are discussed below.
Diffusion Drug Delivery System
This system works on the Fick’s law of diffusion. The drug diffuses across the
membrane, and thus the membrane thickness plays an important role in its effective
and efficient delivery. This system is widely used on commercial scale due to its
advantages. Commonly, it uses drugs in any of the available forms, such as tablets,
implants, and patches.
The drug delivery system is developed based on the interactions and feasibility
between the materials of the systems, consisting of the drug and delivery mechanism. In membrane-based drug delivery systems, the effectiveness and efficiency of
the drug delivery depend upon the diffusion of the drug across the polymeric
membrane. Predictive methods, such as Hildebrand’s and Flory-Huggins theories,
are used for the prediction of drug diffusion across the membrane. The Hildebrand’s
theory helps in predicting the drug’s solubility in a solvent, and Flory-Huggins
theory is used to predict the drug’s solubility in a polymer [1]. These predictive
membranes help in predicting the course of the drug in the drug delivery system
ranging from its melting to permeation across the membrane by formulating a
relation between these two processes, thereby, facilitating the effective and efficient
controlled delivery of the drug.
Osmotic Drug Delivery System
This drug delivery system, as suggested by the name, is similar to osmosis. In this
system, a membrane is used as a drug reservoir as it allows permeation of water but
not of the drug. However, when the reservoir is filled with water, it releases the drug,
thereby, making it an efficient drug delivery system that delivers drugs at a higher
rate. The system is generally in the form of a capsule made from a hydrophilic
polymeric membrane. These systems are various osmotic drug delivery systems
developed over the time, namely, Rose-Nelson (1955), Higuchi-Leeper and
Higuchi-Theeuwes (1970), and Theeuwes (1987) system [28].
In these systems, as discussed, membranes are employed in different forms for
drug delivery, such as reservoirs or matrix. Both active and passive modes of
diffusion are used under these systems. Under active diffusion, a driving force,
such as pH or electric potential, regulates the drug delivery. On the other hand,
under passive diffusion, generally concentration difference is the only driving force
responsible for the drug delivery. Furthermore, the development in stimuliresponsive membranes allows better use of membranes for the effective and efficient
drug deliveries. The detailed discussion on stimuli-responsive membranes is
presented in Sect. 1.6.3.
Membrane Technology in Bioprocess Engineering
21
effective drug delivery system that can provide the drug on specific time in required
dosage at a given site. Nowadays, membrane separation processes are used for the
development of an efficient and effective drug delivery system [1–3]. Mainly, there
are two types of membrane systems based on the mechanism of drug delivery,
namely, diffusion and osmotic drug delivery systems. These membrane-based drug
delivery systems are discussed below.
Diffusion Drug Delivery System
This system works on the Fick’s law of diffusion. The drug diffuses across the
membrane, and thus the membrane thickness plays an important role in its effective
and efficient delivery. This system is widely used on commercial scale due to its
advantages. Commonly, it uses drugs in any of the available forms, such as tablets,
implants, and patches.
The drug delivery system is developed based on the interactions and feasibility
between the materials of the systems, consisting of the drug and delivery mechanism. In membrane-based drug delivery systems, the effectiveness and efficiency of
the drug delivery depend upon the diffusion of the drug across the polymeric
membrane. Predictive methods, such as Hildebrand’s and Flory-Huggins theories,
are used for the prediction of drug diffusion across the membrane. The Hildebrand’s
theory helps in predicting the drug’s solubility in a solvent, and Flory-Huggins
theory is used to predict the drug’s solubility in a polymer [1]. These predictive
membranes help in predicting the course of the drug in the drug delivery system
ranging from its melting to permeation across the membrane by formulating a
relation between these two processes, thereby, facilitating the effective and efficient
controlled delivery of the drug.
Osmotic Drug Delivery System
This drug delivery system, as suggested by the name, is similar to osmosis. In this
system, a membrane is used as a drug reservoir as it allows permeation of water but
not of the drug. However, when the reservoir is filled with water, it releases the drug,
thereby, making it an efficient drug delivery system that delivers drugs at a higher
rate. The system is generally in the form of a capsule made from a hydrophilic
polymeric membrane. These systems are various osmotic drug delivery systems
developed over the time, namely, Rose-Nelson (1955), Higuchi-Leeper and
Higuchi-Theeuwes (1970), and Theeuwes (1987) system [28].
In these systems, as discussed, membranes are employed in different forms for
drug delivery, such as reservoirs or matrix. Both active and passive modes of
diffusion are used under these systems. Under active diffusion, a driving force,
such as pH or electric potential, regulates the drug delivery. On the other hand,
under passive diffusion, generally concentration difference is the only driving force
responsible for the drug delivery. Furthermore, the development in stimuliresponsive membranes allows better use of membranes for the effective and efficient
drug deliveries. The detailed discussion on stimuli-responsive membranes is
presented in Sect. 1.6.3.
Membrane Technology in Bioprocess Engineering
21