THE RISE AND RISE OF DRUG DELIVERY. ORAL ROUTE. Released drug is absorbed in small intestine. Advantages: - patient acceptance - convenient Disadvantages: - poor uptake — rapidly metabolized - chemical instability in GI tract
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- chemical instability in GI tract
A tablet is a hard, compressed medication in round, oval or square shape.
Types of tablets:
1- Disintegrating tablet (conventional or plain tablet)
Single layer tablet
2- Chewable tablets
- Easy administration, especially for infants and elderly people.
3- Effervescent tablets
- Effervescent tablets are dropped into a glass of water before administration during which CO2 is liberated.
1- To obtain rapid drug action, for example analgesics and antacids.
2- To facilitate drug intake, for example vitamins
4- Sublingual and Buccal tablets
- Local medications in the mouth or throat, e.g. local anaesthetics, antiseptics and antibiotics.
1- Hard gelatin capsules
- The capsule consists of two halves and filled with powder.
2 Soft gelatin capsules:
chewable soft gelatin capsules of omega-3
1- Fast dissolving oral film:
- Decreased in dosing frequency
- Sustained & Consistent blood level within the therapeutic window.
- Enhanced bioavailability
- Improved patient compliance
I. Osmotic Drug Delivery Devices:
They fall in two categories
E.g. Implantable Miniosmotic pump
E.g. Elementary osmotic pump
E.g. Elementary osmotic pump
E.g. Push pull osmotic pump
E.g. Osmotic pump with non
expanding second chamber
2- Controlled drug delivery systems
I. The osmotic-controlled release oral delivery system, OROS:
- It is an advanced drug delivery technology that uses osmotic pressure as the driving force to deliver pharmacotherapy, usually once-daily, in several therapeutic areas.
A- The elementary osmotic pump
It is only suitable for the delivery of water-soluble drugs.
B- The two-layer osmotic push–pull tablet
- The polymeric expanding compartment (push layer) provides additional force on the drug layer to ensure that the drug is delivered through the delivery orifice at the target rate.
C- The advanced longitudinally compressed tablet multilayer formulation
D- The L-OROS system
- This system consists of a semipermeable membrane coating that encloses a liquid drug layer and osmotic push layer.
E- Sandwiched Osmotic Tablets (SOTS)
II. pH sensitive systems
adhesive patch that is placed on the
skin to deliver a specific dose of medication
through the skin and into the bloodstream.
-Avoids vagaries associated with gastrointestinal absorption due to pH, enzymatic activity, drug-food interactions etc.
-Substitutes oral administration when the route is unsuitable as in case of vomiting, diarrhea.
- Avoids hepatic “first pass” effect.
- Avoids the risks and inconveniences of parenteral therapy.
- The barrier function of the skin changes from one site to another on the same person, from person to person and with age.
A-membrane based : Release rate constant (rate-limited by diffusion through membrane)
B- monolithic patch
- C0 >> Cs drug dissolution in polymer matrix controls release rate.
The Latest Approaches for Enhancing Transdermal Drug Delivery
-Various technologies have been developed to bypass or modulate the barrier function of the skin.
Iontophoresis is an effective and painless method of delivering medication to a localized tissue area by applying electrical current to a solution of the medication.
II. Reverse iontophoresis:
This process, in which brief, intense electric charges create small pores in the phospholipid bilayer of cell membranes, can assist in the transdermal delivery of drugs.
Electroporation appears to reversibly disrupt the lipid bilayers in the stratum corneum, and the channels it creates are said to promote the passage of hydrophilic drugs through the skin.
ii) When the electric field is applied, the ions move according to their charge.
iii) Pathways are formed across the cell membrane allowing DNA to enter.
iv) When the electric field is deactivated, the membrane heals.
- The use of ultrasound of a suitable frequency to enhance skin permeability seems to be a useful alternative technique for delivering drugs through the skin and can be applied to vaccination and gene therapy.
Enhanced Transdermal Permeation by Cavitation upon application of Ultrasound
IV. Microneedles (Microporation):
An array of stainless silicon microneedles
An array of stainless steel microneedles
Microscope image shows an array of hollow microneedles
next to a hypodermic needle typical of those now used to
inject drugs and vaccines
V. Needleless Jet Injectors:
VI. Medicated Tattoos:
- modified the temporary tattoo popular with children and young adults to contain an active drug for transdermal delivery