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Liquisolid technique: a promising alternative to conventional coating for improvement of drug photostability in solid dosage forms.

Expert opinion on drug delivery (2013-05-28)
Ahmed Khames
ABSTRACT

The objective of this study was to investigate the photoprotective effect of liquisolid technique on amlodipine, a calcium channel blocker antihypertensive drug, representing a photosensitive drug model. Several liquisolid formulations were prepared using propylene glycol as a water-miscible nonvolatile vehicle at drug/solvent ratio (1:1), Avicel PH 102 as a carrier, nanometer-sized amorphous silicon and titanium dioxide either alone or in combination as coating materials. The carrier/coat ratio (R) was varied from 5 to 50. The prepared liquisolids, coated, noncoated tablets and drug substance were irradiated with a light dose of 0.5 W/m(2)/h visible light, 55.1 W/m(2)/h UVA, and 0.247 W/m(2)/h UVB for 8 h. The effect of coating material type and (R) value on the drug dissolution rate and photostability was studied. Results were statistically analyzed by post hoc two-way ANOVA at a probability level (α = 0.05). The results indicated that liquisolid technique not only improved the dissolution rate, but also significantly inhibited the photodegradative effect of different light energies in all prepared liquisolid formulations. The residual drug percentage reached 97.37% in comparison to 73.8% for the drug substance after 8 h of irradiation. The residual drug percentage was affected by the (R) value. Statistically; the detected difference was significant at the selected probability level (α = 0.05). It can thus be concluded that this liquisolid technique is a promising alternative to conventional coating procedures in formulations containing photosensitive drugs.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Propylene Glycol, meets USP testing specifications
Sigma-Aldrich
Propylene glycol, FCC, FG
Sigma-Aldrich
1,2-Propanediol, ACS reagent, ≥99.5%
Supelco
Propylene glycol, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
1,2-Propanediol, ReagentPlus®, 99%
Supelco
Amlodipine besylate, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
1,2-Propanediol, puriss. p.a., ACS reagent, ≥99.5% (GC)
Sigma-Aldrich
1,2-Propanediol, meets analytical specification of Ph. Eur., BP, USP, ≥99.5%
Sigma-Aldrich
(S)-(+)-1,2-Propanediol, 96%
Supelco
1,2-Propanediol, analytical standard
Sigma-Aldrich
Amlodipine besylate, ≥98% (HPLC)
Amlodipine besylate, European Pharmacopoeia (EP) Reference Standard
Amlodipine for peak identification, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
(R)-(−)-1,2-Propanediol, 96%
Sigma-Aldrich
1,2-Propanediol, tested according to Ph. Eur.