Skin toxicity of propranolol in guinea pigs

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.

Topical propranolol therapy for infantile hemangiomas

The nonselective beta-adrenergic receptor antagonist propranolol is an effective therapy for infantile hemangiomas. Systemic propranolol therapy shows a rapid therapeutic effect with good drug tolerability. We report on the efficacy of local application of propranolol ointment in superficial hemangiomas of the skin. In our outpatient department, 45 children with 65 hemangiomas were treated with 1% propranolol in a hydrophilic ointment topically applied twice a day. Before start of treatment and at each visit, clinical photographs were taken. If ultrasound did not confirm occult deeper components, children were included in the study. Treatment in the proliferative phase within the first 6 months of life (including seven preterm infants) induced regression in 59% and cessation of growth in 26% of the hemangiomas. No response or proliferation of subcutaneous components was observed in 15%. Clinically, no side effects caused by the beta-receptor blocker were noticed. Treatment of two ulcerated hemangiomas of the perineal region twice using a flash lamp pulsed-dye laser and propranolol ointment in the surrounding lesion led to healing of the ulcers in 3 and 6 weeks, respectively. In six patients, topical therapy was started between the ages of 7 and 33 months. Even in these hemangiomas, improvement was obvious after 2 or 3 months. Propranolol administered topically in 1% ointment could have a beneficial effect on superficial hemangiomas of the skin. The treatment was well tolerated without side effects even in preterm infants and in children with numerous or large lesions.

Effects of Ethylcellulose and 2-Octyldodecanol Additives on Skin Permeation and Irritation with Ethylene-Vinyl Acetate Copolymer Matrix Patches Containing Formoterol Fumarate

Skin permeation of formoterol fumarate (FF) and irritation with ethylene-vinyl acetate (EVA) copolymer matrix patches was investigated using rat and human skin in vitro and different species of experimental animal, respectively. Skin permeation of FF increased remarkably without addition of ethylcellulose (EC) and was remarkably enhanced by incorporation of 2-octyldodecanol (OD) instead of hydrogenated rosin glycerol ester (Ester Gum H). Effects on skin permeation of FF with EVA matrix patches were similar in rat and human skin, but rat skin was 1000 times more permeable than human skin after 24 h. The primary irritation indices for matrix patches without EC and with EC (OD-0), EC and 0.5 mg OD per square centimeter (OD-0.5), and EC and 1.0 mg OD per square centimeter (OD-1) were 1.46, 1.13,1.29 and 1.38. The results suggested that the irritation induced by these patches was rather mild, but significantly greater than the 0.21 observed with the control. No significant effects were noted for either EC or OD alone. Skin irritation intensity with EVA matrix patches was observed to be in the order of rabbits, guinea pigs, rats and miniature swine.