Iontophoretic in vivo transdermal delivery of beta-blockers in hairless rats and reduced skin irritation by liposomal formulation

Oleic Acid Vesicles for Transdermal Delivery of Propranolol Hydrochloride: Development and Characterization

Background:

Pharmaceutical scientists are exploring transdermal route for treatment of various systemic diseases nowadays. Transdermal nanocarrier systems show various advantages like bioavailability enhancement of drugs, avoidance of first pass hepatic metabolism, and reduction of dosing frequency of bioactive therapeutic molecules.

Objective:

The objective of the present research work was to encapsulate Propranolol hydrochloride into oleic acid vesicles and carry out in-vitro and in-vivo evaluation of oleic acid vesicular gel containing Propranolol hydrochloride.

Method:

Propranol hydrochloride loaded oleic acid vesicles were prepared by exploring thin film hydration method. Developed vesicles were evaluated for morphology, size, zeta potential and polydispersity index (PDI). Thermal behavior of drug loaded vesicles was checked using differential scanning calorimetry (DSC) and depth of skin penetration was determined using confocal laser scanning microscopy (CLSM). Oleic acid vesicles dispersed in Carbopol 934R gel were subjected to in-vivo evaluation in male Sprague Dawley rats through measurement of plasma concentration and tissue distribution of Propranolol hydrochloride.

Results:

Optimized formulation having oleic acid : Propranol hydrochloride in the ratio 7 : 3 showed highest entrapment (56.1 ± 0.7%), acceptable size (291.3 ± 2.2 nm), the optimum value of PDI (0.219 ± 0.043) and zeta potential (-27.13 ± 0.25 mV). The results of DSC analysis showed effective encapsulation of drug inside the vesicles and CLSM analysis revealed penetration of vesicles upto stratum spinosum layer of skin. The results of in-vivo study revealed capability of vesicular gel to prolong the release of Propranolol hydrochloride upto 24 h with a Cmax value of 83.6 ± 3.0 ng/mL which was higher compared to the marketed tablet of Propranolol hydrochloride [InderalR (40 mg), Abbott India Ltd.] (45.6 ± 3.1 ng/mL). Tissue distribution studies revealed higher percentage of Propranolol hydrochloride in various organs after 24 h of administration of vesicular gel compared to marketed tablet.

Conclusion:

Developed oleic acid vesicular gel could be effective to reduce dosing frequency and avoid side effects of oral Propranol hydrochloride.

Noninvasive transdermal delivery of liposomes by weak electric current

Noninvasive transdermal drug delivery (NTDD) offers an exciting new method of administration relative to conventional routes, but is associated with some challenges. Liposomes are capable of encapsulating transdermally-unfavorable drugs. However, the horny layer of skin is a significant barrier that limits efficient transdermal delivery of liposomes. Iontophoresis using weak electric current (WEC) represents a NTDD technology. WEC treatment of liposomes applied to the skin surface improves transdermal penetration of encapsulated drugs by cooperative effects. In this review, we provide an overview of the application of WEC/liposomes for transdermal delivery of macromolecules and low molecular weight drugs. We compare the transdermal delivery and therapeutic efficiency of the combined system with conventional routes of administration and their individual use. We discuss a novel perspective on the mechanism of WEC-mediated transdermal delivery of liposomes, which suggests that WEC activates the intracellular signaling pathway for transdermal permeation and induces unique endocytosis in skin cells.

Liposomal Encapsulation for Systemic Delivery of Propranolol via Transdermal Iontophoresis Improves Bone Microarchitecture in Ovariectomized Rats

The stimulatory effects of liposomal propranolol (PRP) on proliferation and differentiation of human osteoblastic cells suggested that the prepared liposomes-encapsulated PRP exerts anabolic effects on bone in vivo. Iontophoresis provides merits such as sustained release of drugs and circumvention of first pass metabolism. This study further investigated and evaluated the anti-osteoporotic effects of liposomal PRP in ovariectomized (OVX) rats via iontophoresis. Rats subjected to OVX were administered with pure or liposomal PRP via iontophoresis or subcutaneous injection twice a week for 12 weeks. Changes in the microarchitecture at the proximal tibia and the fourth lumbar spine were assessed between pure or liposomal PRP treated and non-treated groups using micro-computed tomography. Administration of liposomal PRP at low dose (0.05 mg/kg) via iontophoresis over 2-fold elevated ratio between bone volume and total tissue volume (BV/TV) in proximal tibia to 9.0% whereas treatment with liposomal PRP at low and high (0.5 mg/kg) doses via subcutaneous injection resulted in smaller increases in BV/TV. Significant improvement of BV/TV and bone mineral density (BMD) was also found in the fourth lumbar spine when low-dose liposomal PRP was iontophoretically administered. Iontophoretic low-dose liposomal PRP also elevated trabecular numbers in tibia and trabecular thickness in spine. Enhancement of bone microarchitecture volumes has highlighted that liposomal formulation with transdermal iontophoresis is promising for PRP treatment at the lower dose and with longer duration than its clinical therapeutic range and duration to exhibit optimal effects against bone loss in vivo.

Prospects of iontophoresis in cardiovascular drug delivery

Clinical benefits, industry interest, regulatory precedence, and strong market potential have made transdermal research the fastest growth area in drug delivery. As most drugs permeate poorly through skin, a major challenge is achieving the therapeutic level by enhancement of permeation rate. Iontophoresis, utilizing a minimal amount of current, is found to affect the skin permeation process drastically. Ideally suited for protein drugs, attempts have been made to utilize the technology for accelerating the low-molecular-weight drugs for chronic administration. However, because of the difficulty associated with the energy supply, commercialization was not feasible until recent times. Fortunately, the unprecedented growth of microelectronics has bridged this lacuna and brought the technology right into limelight. This article analyses the advantages of electrically assisted drug delivery in relation to passive permeation, with special reference to some cardiovascular drugs, for which there is already a demand in the market.

Formulation study of a patch containing propranolol by design of experiments

OBJECTIVE

To evaluate the feasibility of a transdermal patch containing propranolol (PR).

METHOD

Skin penetration enhancers (SPEs) able to improve the skin permeability of PR were selected and a quality by design approach was applied to the development of the patch by a 2(4) full factorial design. The permeation profile of PR from the formulations was assessed in in vitro permeation studies performed by using Franz diffusion cells and human epidermis as membrane. Finally, skin irritation was evaluated by the Draize test.

RESULTS

N-methyl pyrrolidone (NMP) resulted as the best SPE: in addition, the critical factors influencing the PR diffusion through the human epidermis when loaded in the patch resulted in the matrix thickness (X1, p = 0.0957) and PR content (X3, p = 0.0004) which improved the flux; conversely, NMP lacked its enhancement effect when loaded in the patch and the increase in its concentration (X4, p = 0.006) affected the drug permeation through human epidermis. The flux of optimal formulation was 12.7 μg/cm(2)/h. On the basis of the steady-state concentration and clearance of PR, the estimated patch surface was 100-120 cm(2), since the activity of PR is related to its Senantiomer and no in vivo bioconversion occurs.

CONCLUSION

A patch containing (S)-PR was prepared and the (S)-PR flux (13.3 μg/cm(2)/h) permitted to confirm the suitability of a transdermal administration of PR. In particular, the use of a 50 μm thick methacrylic matrix containing 8% (S)-PR and 15% NMP can allow to develop a patch non-irritating to the skin, in order to ensure a constant permeation flux of PR over 48 h.

Cardiovascular effects of transdermally delivered bupranolol in rabbits: effect of chemical penetration enhancers

Bupranolol is a promising candidate for transdermal drug delivery system (TDDS) development. The effect of permeation enhancers on the in vivo delivery and beta-blocking effect of reservoir type TDDS was studied in comparison with intravenous BPL in rabbits. The beta-blocking effect was quantified by measuring the inhibition of isoprenaline induced tachycardia in rabbits after BPL administration via transdermal and intravenous routes. The reservoir type TDDS containing a hydroxypropyl cellulose gel and polyethylene membrane was used as a control device. In comparison, the TDDS containing skin penetration enhancers, either 2-pyrrolidone or partially methylated beta cyclodextrin (PMbetaCD) were evaluated. The control device (no enhancer) produced about 52% inhibition of isoprenaline induced tachycardia at 2 h and the effect continued over 24 h application period, however, the devices with 2-pyrolidone or PMbetaCD produced about 85% inhibition of isoprenaline induced tachycardia at 3 h and the same effect continued over 24 h application period. Likewise, the AUC of these devices were significantly higher than that of control device. The intravenous bupranolol showed rapid decline in the pharmacodynamic effect with time indicating its rapid elimination. The in vivo delivery of bupranolol (as estimated by a mass balance study) from the devices made with pyrolidone or PMbetaCD was 3-fold higher than that of control. The results of this study strongly suggest that the penetration enhancers in the TDDS increased the in vivo delivery of BPL, thereby increased the beta-blocking activity of BPL by 50-60% higher than control, enabling the reduction of the TDDS patch size, accordingly.

Transdermal delivery of beta-blockers

Beta-adrenoceptor blocking drugs (beta-blockers) are one of the most frequently used class of cardiovascular drugs that are mainly used in conventional dosage forms., which have their own limitations including hepatic first-pass metabolism, high incidence of adverse effects due to variable absorption profiles, higher frequency of administration and poor patient compliance. Essentially, attempts have been made to develop novel drug delivery systems for beta-blockers, including transdermal delivery systems, to circumvent the drawbacks of conventional drug delivery. However, so far none of the beta-blocker drugs have been marketed as transdermal delivery systems. Nevertheless, there have been noteworthy research endeavours worldwide at the laboratory level to investigate the skin permeation and to develop transdermal formulations of beta-blockers including: propranolol, metoprolol, atenolol, timolol, levobunolol, bupranolol, bopindolol, mepindolol, sotalol, labetolol, pindolol, acebutolol and oxprenolol. Innovative research exploiting penetration-enhancing strategies, such as iontophoresis, electroporation, microneedles and sonophoresis, holds promise for the successful use of these drugs as consumer-friendly transdermal dosage forms in clinical practice. This paper presents an overview of the transdermal research on this important class of drugs.

Facilitated skin penetration of lidocaine: Combination of a short-term iontophoresis and microemulsion formulation

The objective of this study was to demonstrate the potential of the application of a short-term iontophoresis on the topical delivery of lidocaine hydrochloride from a microemulsion-based system. Five- and 10-min durations of anodal iontophoresis applied onto porcine skin were examined in combination with a microemulsion containing 2.5% lidocaine hydrochloride. A similar combination (10-min iontophoresis with microemulsion in the anodal electrode) was also examined in vivo in a rat model. It was shown in vitro that by combining microemulsion application with a 10-min iontophoresis of 1.13 mA/cm2 electric current density, a significantly increased flux was obtained compared with a combination of aqueous drug solution with the same iontophoresis protocol. In vivo studies revealed that 57.71 +/- 18.65 and 18.43 +/- 9.17 microg cm(-2) were reached in the epidermis and dermis, respectively, at t = 30 min of microemulsion application, when iontophoresis was applied for 10 min. In contrast, the application of aqueous solution-iontophoresis resulted in a relatively lower drug accumulation (21.44 +/- 10.42 and 5.30 +/- 2.25 microg cm(-2) in the epidermis and dermis, respectively, at t = 30) with more rapid clearance of the drug from the skin. Ten-minute application of a low-current electric field on a new topical microemulsion appears to make significant changes in skin permeability. The potential advantages of this procedure include significantly increased flux, accumulation of a large skin drug depot, short lag times, reduced irritation (compared to long-term iontophoresis), simplicity and ease of compliance.