Abstract
The aim of the present investigation was to develop sustained release ethylcellulose-coated egg albumin microspheres of diltiazem hydrochloride (DH) to improve patient compliance. The microspheres were prepared by the w/o emulsion thermal cross-linking method using different proportion of the polymer to drug ratio (1.0:1.0, 1.0:1.5 and 1.0:2.0). A 32 full factorial design was employed to optimize two independent variables, polymer to drug ratio (X1) and surfactant concentration (X2) on dependent variables, namely % drug loading, % drug release in 60 min (Y60) and the time required for 80 % drug release (t80) were selected as dependable variable. Optimized formulation was compared to its sustained release tablet available in market. The polymer to drug ratio was optimized to 1:1 at which a high drug entrapment efficiency 79.20% ± 0.7% and the geometric mean diameter 47.30 ± 1.5 mm were found. All batches showed a biphasic release pattern; initial burst release effect (55% DH in 1 h) and then were released completely within 6 h. In situ coating of optimized egg albumin DH microspheres using 7.5% ethylcellulose significantly reduced the burst effect and provided a slow release of DH for 8-10 h. Finally, it was concluded that ethylcellulose-coated egg albumin DH microspheres is suitable for oral SR devices in the treatment of angina pectoris, cardiac arrhythmias, and hypertension due to their size and release profile.
Highlights
Diltiazem hydrochloride (DH) is a calcium channel blocker that relaxes vascular smooth muscle and dilates coronary arteries by altering the calcium flux into the cell.[1]
Egg albumin flakes and light paraffin oil of Laboratory Rasayana grade were procured from Ases laboratory, India, and Gujarat Pharmaceuticals Ltd., India, respectively
Preparation of egg albumin microspheres Egg albumin microspheres of DH were prepared by the w/o emulsion thermal cross-linking method with minor modification.[25,26,27,28,29]
Summary
Diltiazem hydrochloride (DH) is a calcium channel blocker that relaxes vascular smooth muscle and dilates coronary arteries by altering the calcium flux into the cell.[1]. Attempts have been made to develop twice a day of oral sustained release dosage formulation for achieving better patient compliance and relative constant blood levels. It is readily absorbed from the gastrointestinal tract and undergoes substantial first-pass metabolism. The systemic bioavailability of the immediate-release preparation is approximately 40%-50%, with an elimination half-life of 3.5-7 h.[3] Sustained-release DH has been reported to reduce tachycardia without inducing excessive bradycardia and does not significantly reduce baseline heart rate below 74 beats/min.[4] Because of its low bioavailability and short half-life attempts have been made to develop sustained release products and a reduced dosing frequency.[5]
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