Background::Cardiac arrhythmia, is a medical condition that reduces the heart’s efficiency
in pumping blood, and can be fatal, requires long-term management with conventional drugs, despite
their limited efficacy. Diltiazem hydrochloride, chosen as a model drug, has a short biological
half-life and extensive metabolism. Administering drug through skin is challenging, particularly due
to the penetration via stratum corneum. However, solid lipid nanoparticles as a particulate carrier
system can enhance its permeation and bioavailability.
Objective::The study aimed to develop a matrix type transdermal patch with diltiazem hydrochloride
encapsulated in solid lipid nanoparticles
Methods::The study used the solvent diffusion technique to prepare SLNs by mixing the drug and
solid lipid in an organic phase at 80°C, then slowly adding it to an aqueous phase with continuous
stirring for 45 minutes. The resulting nanodispersion was freeze-dried and analyzed for morphological
studies, encapsulation efficiency & drug content. A patch was formulated using solvent evaporation
technique, incorporating HPMC E50 (2% w/v), propylene glycol, and ethanolic oleic acid
(1.5% v/v). SLNs loaded with diltiazem hydrochloride taken equivalent to diltiazem hydrochloride
dose in the transdermal patch. The patch was then evaluated for In vitro and skin permeation studies.
Results::The result showed a positive correlation between lipid concentration and particle size.
Probe sonication and homogenization increased particle size, while stirring speed reduced it. SEM
and TEM images confirmed spherical particles with a size of 488.1±4.01nm and an entrapment efficiency
of 55.03±1.99%. Drug release studies demonstrated 70.7% drug release from lipid matrix
over 24 hrs. The formulated patch with uniform SLN distribution, had a drug content 89.37 ±
0.04% with a surface pH of 6.1 ± 0.53, close to skin pH. The uniformity of content in 3x3 patch estimated
to be 14.587 ± 1.404 mg, close to the theoretical content 16.318 ± 1.08 mg, confirmed homogenous
distribution of diltiazem hydrochloride SLNs throughout the patch diameter. Cumulative
amount released from patch formulation at pH 5.6 and pH 7.4 was 518.1414μg/cm2 and 404.4466
μg/cm2. Synergistic flux enhancement was observed with oleic acid propylene glycol blend. Ex vivo
study of the patch showed steady-state flux of 6.9 μg/cm2/hr, permeability coefficient 0.00362
cm/hr, diffusion coefficient 0.000103 cm/hr, cumulative drug permeation (Dmax) 814.885 μg after
24 hrs, and followed a Higuchi-matrix release model.
Conclusion::The developed patch possessed improved bioavailability with reduced dosing and enhanced
patient compliance.