About author :
S.S Siddheshwar*, M. R. Shiradkar, S.B. Somwanshi, R.T. Dolas, A.N. Merekar, S. R. Pattan
Dept. of Pharmacy, Acharya Nagarjuna University, Guntur (A.P), India
The major drawback of drug administered subcutaneously is its invasiveness, which leads to pain and discomfort to the patients. Drug delivery using patches and diffusion through the skin has the merit of being painless, but is suitable only for drugs of low molecular weight, and this excludes the majority of drugs and vaccines. Liquid jet injectors are no less painful for delivering the drug to skin. The Powder Ject system of transdermal delivery of powdered drug involves the propulsion of solid drug particles into the skin by means of a high-speed gas flow. The Powder Ject system fires solid particles (20–100 µm) through stratum corneum into lower skin layers,using a supersonic shock wave of helium gas .This needle-free method of transdermal drug delivery is painless, causes no bleeding, and causes negligible damage to the skin. Many researchers have patented for the delivery of drugs to skin or mucosal surfaces by the PowderJect method which ensures its potential advantages in pharmaceutical drug delivery.
Key words: PowderJect, transdermal, needle-free method, drug delivery
Core technology of PowderJect:
The core technology involves the high-velocity injection of particle-formulated drugs or vaccines into any physically accessible tissue. The basic principle is that solid-form particles can be painlessly and effectively delivered into the body if they are appropriately formulated and are travelling at a sufficiently high velocity. This principle can be applied to deliver any drug or vaccine that can be formulated as a solid particle of the appropriate size, mass, density, and strength. By using the appropriate PowderJect system, this technique may be employed to deliver a range of drugs into the skin (transdermal), the tissues of the mouth and vagina (transmucosal), or directly into other tissues via catheter or minimally invasive surgical entry.
Dermal PowderJect Device :
Actuation of the PowderJect system opens a gas canister, which allows helium gas at high pressure to enter a chamber at the end of which is a drug. The particles have sufficient momentum to penetrate the skin while the helium gas is reflected into a silencer. Individual tiny particles of powder pass through the outer layer of the skin (stratum corneum), penetrating down to the required level in the tissue. The drug dissolves and then either acts locally or diffuses into the bloodstream to deliver its therapeutic effect.
Most drugs with a systemic action, such as proteins and peptides, are ideally delivered to the dermis to target the area with the highest density of blood capillaries. Conventional and DNA vaccines are ideally delivered into the epidermis. The PowderJect system delivers an intradermal injection. The depth of penetration of the drug particles is optimized by adjusting the momentum density of the particles within the gas flow. Particle mass and area are controlled through formulation and processing of the drug. Particle velocity is controlled within the device by three parameters: nozzle geometry, membrane burst strength, and gas pressure.Drugs that require self-administration, or local delivery to sensitive sites, can be made more attractive for the patient with this technology.
Advantages of PowderJect System: includes
a) Pain-free delivery — particles are too small to trigger pain receptors in skin
b) Improved efficacy and bioavailability
c) Targeting to a specific tissue, such as a vaccine delivered to epidermal cells
d) Sustained release, or fast release
e) Accurate dosing
f) Overcomes needle phobia
g) Safety — the device avoids skin damage or infection from needles or splashback of body fluids particularly important for HIV and hepatitis B virus
FUTURE PROSPECTS AND CONCLUSION
PowderJect technique is use to increase the mass of drug delivered transdermally, and to deliver it to a chosen layer of skin. This requires the formulation of drug particles of carefully controlled size and density that are sufficiently robust to remain intact after impact with the skin, which requires the design of compact devices that deliver drug particles at uniform velocity, to a target diameter of 20–100 µm, with uniform spatial distribution. Therefore development requires in device design and particle formulation to improve dose accuracy and the range of drugs that can be delivered by this needle free and painless method.