One dose for immediate release and another dose for delayed release (or 2nd dose)
Multiple layered or tablet within a tablet
Repeat action
Release is direct toward a specific body region, tissue, or site
enteric coating
Target release
Rate controlled delivery systems
applicable to numerous dosage forms
rate of drug delivery is controlled by feature of the device
MTC
Minimum Toxic Concentration
MEC
Minimum effective concentration
Advantages of Solid Oral Modified-Release
Reduction in drug blood level fluctuations
Frequency reduction in dosing
Enhanced convenience and compliance
Reduction in side effects
Reduction in overall helath care costs
Disadvantages of Solid Oral Modified-Release
No flexibility in adjusting drug dose and or dosage regiment
Dose dumping
What are the attributes of drugs that are good candidates for extended-release products
Neither very slow nor very fast rates of absorption and excretion (inherently long-acting drugs and short life)
Uniformly absorbed from GI tract
Administered in relatively small doses
Good margin of safety, wide therapeutic index
Therapeutic index
median toxic dose/median effective dose
Oral extended-release products
Provide immediate release of one dose of drug for prompt therapeutic effect followed by gradual and continual release of additional doses to maintain effect over an extended period of time
Additional "maintenance" doses are released at a rate correspondent to the amount being metabolized and excreted
Dissolve in GI fluids
Maintain sufficient GI residence time
Extended-release technolgoy
Coated beads, granules or microspheres
Multitablet system
Microencapsulated drug
Drug embedded in slwly eroding or hydrophilic matrix
Drug embedded in inert plastic matrix
Complex formation
Ion-exchange resins
Osmotic pump
Doryx
Coated doxycycline hyclate pellets
Eric
erythromycin delayed-release capsules with enteric coated pellets of erythromycin base