FORMULATION AND EVALUATION OF
FLOATING TABLETS OF ENALAPRIL
The aim of the present study was to develop a gastro retentive drug
delivery system containing Enalapril maleate. The preparation of
floating matrix tablets of Enalapril maleate by incorporating low
density polymer Hydroxy propyl methyl cellulose K15 and K50.The
tablets were prepared by wet granulation method of Enalapril
maleate, polymers, and other excipients are mixed and then
compressed on a punching machine..The floating matrix tablets
were evaluated for uniformity weight, hardness, friability, drug
content, and dissolution studies , analytical studies.
Floating drug delivery system is also called the hydro dynamically
balanced system (HBS). Floating drug delivery systems (FDDS)
have a bulk density less than gastric fluids and so remain buoyant in
the stomach without affecting gastric emptying rate for a prolonged
period of time. While the system is floating on the gastric contents,
the drug is released slowly at the desired rate from the system. After
release of drug, the residual system is emptied from the stomach.
This results in an increased GRT and a better control of the
fluctuations in plasma drug concentration.
Floating drug delivery system divided into:
1. Non-effervescent systems
a. Colloidal gel barrier systems
b. Bi-layer floating tablets
c. Micro porous compartment systems
Multi particulate system
Micro balloons / Hollow Microspheres
Volatile liquid containing systems
Gas generating systems
APPLICATION OF FLOATING DRUG
1. Enhanced Bioavailability
2. Sustained drug delivery
3. Site specific drug delivery systems
4. Absorption enhancement
5. Minimized adverse activity at the colon
6. Reduced fluctuations of drug concentration
ADVANTAGES OF FLOATING DRUG DELIVERY
1. Remains in the solution for prolonged time even at the alkaline
pH of the intestine.
2. Advantageous for drugs meant for local action in the stomach
3. Useful for the administration of aspirin and other similar drugs.
4. Minimizing the mucosal irritation due to drugs, by drug
releasing slowly at controlled rate.
5. Ease of administration and better patient compliance.
DISADVANTAGES OF FLOATING DRUG DELIVERY
1. Not feasible for those drugs that have solubility or stability
problems in gastric fluids.
2. The presence of food to delay their gastric emptying.
3. Drugs that cause irritation and lesion to gastric mucosa are not
suitable to be formulated as floating drug delivery systems.
PAST WORK ON IMMEDIATE RELEASE
emulsion solvent diffusion
drug retained in the micro
particles decreased with
increase in ERL content
Karnel et al (2001)
addition of citric acid causes an
enhancement in drug release
Dave et al (2004)
tablet composition and
mechanical strength on the
floating properties and drug
release were improved
Patel et al (2006)
drug delivery was a promising
approach to achieve in vitro
Jaimini et al (2007)
wet granulation technique
Incorporation of hydrophobic
polymer EC in granulation fluid
showed good drug release
Patel et al (2008)
melt granulation technique.
it released the drug in a
Kumar et al (2008)
dry coating technique
dry coated floating duration
with extended release of drug
over a prolonged period of
Abdelbary et al (2010)
Material issuance &
Screening of damp
1. Organoleptic properties:
White off-white yellowish crystalline powder
2. Melting Point Determination: 143-144.5 ºc
3. Solubility : Sparingly soluble in water; freely soluble in
methanol; practically insoluble in methylene chloride. It dissolves
in dilute solutions of alkali hydroxides.
4. Calibration curve: R2 value 0.9994
5. Preformulation studies:
a. Bulk density: 0.64167 gm/ml
b. Tapped density: 0.72-0.79 gm/ml
c. Carr’s index: 9-22.
d. Angle of repose: 22-30
e. Hausner ratio: 1.16-1.17
Hardness: 2.0-4.0 (kg/cm²)
Thickness test: 5.1-5.6 mm
Friability test: below 1.0%
Weight variation: 10.5-11.7%
Buoyancy / Floating Test: Lag time were calculated less than 1
min and floating time maximum 10 hours.
7. Compatibility studies:
a. Fourier Transform Infra-Red Spectroscopy (FTIR): indicating
the absence of any chemical interaction between Enalapril maleate
b. Differential Scanning Calorimetry (DSC): The DSC analysis of
pure ENM showed a sharp endothermic peak at 152.55 C.
From the results and inference we can certainly say that
floating type gastro retentive drug delivery system holds a lot of
potential for drug having limited oral bioavailability due to having a
narrow absorption window in the upper part of small intestine.
Enalapril maleate is very sensitive drug and having stability
problems. We can certainly explore this drug delivery which may
lead to improved bioavailability and ensured therapy with many
existing drugs. It is the responsibility of future scientists working in
this area to effectively use the potential of this drug delivery system
for the benefit of mankind.