Ken Sone

Hydration and occlusion treatment for hypertrophic scars and keloids

In 31 patients with hypertrophic scars or keloids, a side by side test was carried out to check the efficacy of an occlusive dressing technique using cream which did not contain silicone oil, versus a simple application of vaseline, used as a control. In all cases, the cream treated areas of scar and keloid demonstrated a remarkable improvement over that of the vaseline treated area. These findings strongly suggest that the mechanisms of hydration and occlusion are the main basis of the therapeutic action of this method in treating hypertrophic scars and keloids.

Treatment of scars and keloids with a cream containing silicone oil

The clinical effect of silicone cream containing 20% of silicone oil was tested on 47 patients with hypertrophic scars and keloids. A silicone cream/occlusive dressing technique, quite similar in manner to silicone gel treatment, resulted in a remarkable improvement of scars and keloids in 9 of 11 cases (82%) whereas the simple application of the cream onto the scars and keloids of 36 cases resulted in only mild improvement in 8 (22%). Using the chi-square test, a statistically significant difference was seen between these two treatments (p less than 0.01). From these findings, we suggest that occlusion and hydration are the principal modes of action of the silicone gel sheet method and our silicone cream/occlusive dressing technique.

Renal effects of nicardipine in patients with mild-to-moderate essential hypertension

We studied the renal effects of nicardipine, a calcium entry blocker, in seven patients with mild-to-moderate essential hypertension. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by means of thiosulfate and para-aminohippurate, respectively. Intravenous administration of nicardipine hydrochloride (0.5 mg) increased RBF by 26.8 +/- 5.8% (mean +/- SEM, p less than 0.01), GFR by 35.4 +/- 12.4% (p less than 0.05), and urinary excretion of sodium by 56.4 +/- 10.7% (p less than 0.05) with a significant (p less than 0.01) reduction in systolic and diastolic blood pressure as compared to control values. Nicardipine decreased total renal vascular resistance by 30.0 +/- 3.2% (p less than 0.05) from the control value, while filtration fraction remained unchanged. Our results indicate that nicardipine has several favorable renal effects with a concomitant hypotensive action in patients with mild-to-moderate essential hypertension.

Treatment of dermal depth burn wounds with an antimicrobial agent-releasing silicone gel sheet

Silicone gel sheets containing 0.02 per cent Ofloxacin were used in the treatment of 24 patients with a total of 27 dermal depth burn wounds. The gel provided a continuing drug delivery system from the dressing to the wound. Clinically the silicone gel sheets did not adhere to the wound and could be removed easily without pain. No infection developed in any of the dermal depth burn wounds treated with the gel sheets. The silicone gel sheets were found to promote prompt epithelialization in 16 burn wounds of superficial dermal depth (mean 8.4 days) compared with ointment-impregnated gauze dressings (mean 14 days, P less than 0.01). There was less pain and discharge by macroscopic observation of the absorbent materials from both dressings. In nine wounds of mixed superficial and deep dermal burn, the silicone gel also provided prompt epithelialization (mean 12 days) compared to the control wounds (mean 22 days, P less than 0.01).

Silicone gel including antimicrobial agent

Silicone gel sheets containing Ofloxacin (OFLX), that provide a continual drug delivery system from a wound dressing to the wound so as to prevent infection and to promote healing, are described. It was found that silicone gel sheets without added medication did not inhibit microbial growth but that gel sheets containing 0.02% and 0.2% of OFLX had a positive antimicrobial effect against Staphylococcus aureus and Pseudomonas aeruginosa in a dose-dependent fashion in vitro. Further, this antimicrobial efficacy was greatly increased in a silicone gel sheet that contained 0.02% of OFLX and an additional 10% of silicone oil. In animal experiments, a silicone gel sheet containing OFLX prevented microbiol growth and promoted rapid epithelialisation in wounds to which Staphylococcus aureus had been applied, whereas wounds covered only with OpSite all resulted in continued infection.

A silicone gel sheet dressing containing an antimicrobial agent for split thickness donor site wounds

Treatment of a split thickness donor site wound in 20 patients by means of a silicone gel sheet containing Ofloxacin, an antimicrobial agent, has been tested. For a comparison, each wound was divided into two parts, one for the silicone gel treatment and the other with a collagen sheet (10 cases) or an ointment-impregnated gauze (10 cases). Although Staphylococcus aureus was detected in three wounds treated with the collagen sheet, no wound treated with the silicone gel developed an infection even though the infected wound was adjacent. Results have shown that prompt epithelialisation occurred in the silicone gel-covered wounds, with little exudate and pain compared to wounds treated with either of the dressings. Although some wounds treated with the silicone gel tended to exhibit a slightly prolonged redness compared to wounds treated with an ointment-impregnated gauze, no subsequent cosmetic problem resulted.

The relationship between Prostaglandin E1 applied area and flap survival rate

Using a silicone gel sheet continuous drug delivery system containing Prostaglandin E1 (PGE1), the relationship between flap survival rate and the site of drug application was studied. Skin flaps measuring 2 x 9 cm were raised on the dorsum of rats, and divided into 3 areas. Area 1 was within 3 cm of the flap tip, area 2 was between 3-6 cm from the flap tip including the critical zone, and area 3 was the portion within 4 cm of the flap base. Further, area 4 was a strip of skin around the flap, 1 cm in width. Compared to the control group, a significant increase in flap survival rate was seen only when PGE1 was administered to area 2 (p < 0.01, t-test). Specimens injected with dye intravascularly showed an increase in the number of thick vessels in area 3, when PGE1 was applied only to area 3. However, when PGE1 was applied to area 2, there was no significant vascular increase in area 3. Instead, an extensive network of fine vessels was observed in area 2.

A new system of treating wounds by a continuous topical application of medication

A new procedure using a silicone gel sheet that enables the continuous topical application of a drug to a wound, and the effect of this therapeutic procedure on experimental skin flaps of rats, are described. Although a silicone gel sheet without a drug did not augment the flap survival length, silicone gel sheets containing Prostaglandin E1 (PGE1) and Ofloxacin showed significant elongation of the survival length of the flaps without signs of infection. Similarly, silicone gel sheets containing PGE1 inserted under the flap, like a drain, also showed statistically significant augmentation of the flap survival length. These facts showed a therapeutic potential of this new silicone gel sheet containing a drug.

The effect of continuous topical application of heparin on flap survival

To evaluate the beneficial effects of heparin on flap survival area, an experimental study was carried out on dorsal flaps in rats. Topical applications of heparin, released from a silicone gel sheet onto the critical area (which generally necrosed without treatment), resulted in an increase in the flap survival area and rate as compared to controls (p < 0.01). When heparin was applied topically but solely to an area proximal to the critical area however, no increase in the survival area resulted.

A study of topical and systemic Prostaglandin E1 and survival of experimental skin flaps

A study has been undertaken to investigate Prostaglandin E1 administration procedure for improving flap survival. Whether the drug was administered continuously or transcutaneously using a silicone gel drug delivery system; or was topically injected into the critical zone of the flap; or was intraperitoneally administered intermittently over an hour after surgery a statistically significant improvement of flap survival occurred (P < 0.01, Students t-test). However, no improvement of flap survival was seen when the drug was administered only once intraperitoneally immediately after flap elevation, although administered doses of the drug in those rats was equal to the doses in the rats which received intermittent administration of the drug intraperitoneally over an hour after surgery.