In the last blog I covered about the preparation and now let is go through the various evaluation tests followed by advantages, disadvantages and commercially available products.
The following tests must be conducted for the GRDDS.
2.vitro floating study
4.gastro retentive study
Swelling index: Here the dissolution apparatus is used in order to determine the swelling of polymers after absorbing water.
The medium used is 0.1N HCl and 50 to 1000 rotations per minute are maintained at 37 oC. After 1hr remove the tablet and remove the water present on the surface using the blotting paper and then swelling index is calculated.
Swelling index = (wet weight-dry weight/ dry weight ) x 100
In Vitro floating study: here also the dissolution apparatus and medium o.1N HCl or water are used. Floating lag time is measured here which is the time required for the system to float.
Specific gravity: here the displacement method using benzene is done to determine the specific gravity.
Vitro Gastro retentive study: As the name indicates this test in done on the human beings. Where the GRDDS is present can be determined by using the gamma scintigraphy, radiography, gastroscopy, MRI.
1.By the GRDDS, there will be enhanced absorption and therefore there will be enhanced bioavailability of the drug. (1) There will a short gastric residence in case of conventional forms which can be overcome by using thse systems. (2)
2.In the case f stomach if we need a local action this system is best because enough of the drug concentration will be established in the stomach. (1)
3.Since there is a controlled release and hence the number of times the patient has to take the drug will be decreased and hence there will be an increase in the patient compliance. In case of some drugs like famotidine there is a more or less constant level of the drug in the plasma and by using the larger extent of the drug decreases the side effects as well as the bioavailability increases.(1)
4.used for the high potent drugs as we can control the plasma levels. (1)
5.Sustained drug delivery can achieved. (1)
6.In conditions like diarrhea there will severe movement of the intestinal all and hence by making the drug to float in the stomach we can attain better results. (2)
1.These systems should be given after the meals.
2.to maintain the floating the patient is advised to take water regularly.
3.the patient cannot take the drug before going to bed.
4.those which are not stable and soluble in the gastric conditions are not suitable for this systems.
5.the drugs will undergo the first pass metabolism.
COMMERCIALLY AVAILABLE DRUGS (1)
Madopar contains Lovodopa and Benserzide.
Valrelease contains Diazepam.
Topalkan contains Aluminium-Magnesium antacid.
Conviron contains ferrous sulphate.
Cifran OD consists of ciprofloxacin.
Cytotec consists of Misoprostol.
1.Indian Drugs, Scientific and research publication from Indian Drug Manufactures Association, volume 48, issue no 05, may 2011, page no 7 to 11.
2.http://rjptonline.org/RJPT_%20Vol1(4)/8.pdf (accessed on 20th August 2011, 20:45)
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