Methylphenidate vs Metadate
Methylphenidate has a fast dissolution rate
Methylphenidate has a lower total release
Solubility 1
- should be considered along with its dose
- even poorly soluble drugs can completely dissolve under the right conditions with a small dose
- Dose Solubility Volume is more relevant than solubility alone
Solubility 2
- a drug is “low solubility” if more than 250 mL of water is required to dissolve the largest dose at any pH at 37 degrees C
- 250 mL is chosen because it is the assumed minimum initial gastric volume available
Bioavailability
- dependent upon having the drug in solution, but also the drug’s permeability
- many drugs and substances has a permeability to a fraction absorbed of 90% or better
Polymers for Non Enteric Film-Coating
Cellulose coatings
- HPMC
- Methylhydroxyethylcellulose
- ethylcellulose
- HPC
Enteric Polymers
- release drug in small intestine but not the stomach
- OMEPRAZOLE (totally dependent on enteric coating)
- CAP
- HPMCP
- PVAP
Matrix Tablet
- drug embedded in polymer matrix
Erosion: both polymers go away and release drug
Diffusion: drug diffuses out of the polymer (intact)
Osmotic Pump in Concerta
Contains:
- osmotic core
- semipermeable membrane
- delivery orifice (drug released out of) by laser hole delivery
Water can come in, drug stays within
Drug comes out slowly all day long
GI Transit Time of OROS
Stomach (fasted)
- average time is 30 minutes
Stomach (fed)
- average time is 2-3 hours
Small Intestine
- average time is 3 hours
Colon
- average time is 32 hours
Concerta vs Metadate
- advertising about school time frames for drugs
Immediate vs Delayed vs Extended
Immediate: Fast onset of the drug and releases fast –> out of blood in short amount of time
Delayed: Slow and delayed onset of the drug –> out of blood after spiking in short amount of time
Extended: gradual release of the drug over time with a smaller intensity of the drug
OROS vs IR
- IR contained many peaks and valleys in the release of the drug in the blood plasma
- OROS is a constant release of the drug and a constant amount of drug in blood plasma over time
