Acidic fibroblast growth factor: evaluation of topical formulations in a diabetic mouse wound healing model.

The efficacy of topical formulations of acidic fibroblast growth factor (aFGF) in healing of full-thickness wounds has been studied in a diabetic db+/db+ mouse model. The effect of several formulation variables, dose, and application frequency was examined. It was found that wound healing in diabetic animals treated with aFGF or placebo was slower than in their nondiabetic littermates. The availability of aFGF from the viscous vehicle employed in this study (1% hydroxyethyl cellulose) was demonstrated in vitro using diffusion cells. The viscous formulation of aFGF was equally effective in wound healing as a nonviscous formulation in phosphate-buffered saline. A formulation containing heparin (necessary for full biological and conformational stability of aFGF) at a mass ratio of 3:1 to aFGF was more efficacious than formulations with lower heparin: aFGF ratios. Wounds treated with three doses of 3.0 micrograms/cm2 aFGF healed faster than those treated with a single dose of 3.0 micrograms/cm2 aFGF. Three applications of 3.0 or 0.6 microgram/cm2 a FGF were equally effective in accelerating wound healing.

Formulation design of acidic fibroblast growth factor.

The design of an aqueous formulation for acidic fibroblast growth factor (aFGF) requires an understanding of the type of compounds that can either directly or indirectly stabilize the protein. To this end, spectrophotometric turbidity measurements were initially employed to screen the ability of polyanionic ligands, less specific compounds, and variations in solution conditions (temperature and pH) to stabilize aFGF against heat-induced aggregation. It was found that in addition to the well-known protection of aFGF by heparin, a surprisingly wide variety of polyanions (including small sulfated and phosphorylated compounds) also stabilizes aFGF. These polyanionic ligands are capable of raising the temperature at which the protein unfolds by 15-30 degrees C. Many commonly used excipients were also observed to stabilize aFGF in both the presence and the absence of heparin. High concentrations of some of these less specific agents are also able to increase the temperature of aFGF thermal unfolding by as much as 6-12 degrees C as shown by circular dichroism and differential scanning calorimetry. Other compounds were found which protect the chemically labile cysteine residues of aFGF from oxidation. Aqueous formulations of aFGF were thus designed to contain both a polyanionic ligand that enhances structural integrity by binding to the protein and chelating agents (e.g., EDTA) to prevent metal ion-catalyzed oxidation of cysteine residues. While room-temperature storage (30 degrees C) leads to rapid inactivation of aFGF in physiological buffer alone, several of these aFGF formulations are stable in vitro for at least 3 months at 30 degrees C. Three aFGF topical formulations were examined in an impaired diabetic mouse model and were found to be equally capable of accelerating wound healing.

Estradiol distribution and penetration in rat skin after topical application, studied by high resolution autoradiography.

Transdermal pathways and targets in the skin for estradiol were investigated using dry-mount autoradiography. 3H-estradiol-17 beta was applied at doses of 30.1 pmol, 120.4 pmol and 301 pmol/cm2 to shaved rat skin in the dorsal neck region. Vehicles were DMSO, ethylene glycol or sesame oil. After 2 h of topical treatment with 30.1 pmol 3H-estradiol x cm-2 dissolved in DMSO a distinct cellular distribution was apparent. Target cells with concentrations of radioactivity were found in epidermis, sebaceous glands, dermal papillae of hair and fibroblasts. After treatment with 120.4 and 301 pmol/cm2, a penetration gradient of radioactivity was recognizable however it masked specific cellular and subcellular uptake. The stratum corneum accumulated and retained radioactivity, apparently forming a depot for the hormone. Strong concentration and retention of the hormone was conspicuous in sebaceous glands for more than 24 h, suggesting that sebaceous glands serve as a second storage site for the hormone. In all autoradiograms two penetration pathways to the dermis were visible: one through the stratum corneum and epidermis, the other through the hair canals and hair sheaths.

Antiparkinsonian efficacy of a novel transdermal delivery system for (+)-PHNO in MPTP-treated squirrel monkeys.

We examined the ability of the antiparkinsonian agent (+)-4-propyl-9-hydroxynaphthoxazine (PHNO) to enter the systemic circulation in therapeutic concentrations after continuous transdermal absorption in squirrel monkeys rendered parkinsonian by MPTP. Direct subcutaneous administration of (+)-PHNO in the dose range of 2.5 to 20 micrograms/kg restored locomotor activity to levels seen in normal monkeys for approximately 1 hour. Application of transdermal patches capable of delivering, into an infinite sink, an estimated 2.6 micrograms/cm2/h of (+)-PHNO over a skin surface area of 4.78 to 19.12 cm2 also restored locomotor activity to the normal range during a 24-hour period. We suggest the use of transdermal application of PHNO as a novel drug delivery system for the improved management of Parkinson's disease.

The antiparkinsonian actions and pharmacokinetics of transdermal (+)-4-propyl-9-hydroxynaphthoxazine (+PHNO): preliminary results.

(+)-4-Propyl-9-hydroxynaphthoxazine (+PHNO) is a potent dopamine agonist that has been administered transdermally to four patients with Parkinson's disease and "on-off" fluctuations. Skin patches of increasing size were used to treat these patients, who also received infrequent doses of oral levodopa if required. The effect of +PHNO was measured as an increased duration of action of individual levodopa doses. The clinical effect measured in this way was directly proportional to the plasma concentrations of +PHNO achieved. The plasma concentrations of +PHNO began to rise 4-6 h after patch application and reached a steady state by 24 h. The final plasma concentration of +PHNO was proportional to the area of skin covered.

2'-Nor-2'-deoxyguanosine is an effective therapeutic agent for treatment of experimental herpes keratitis.

2'-Nor-2'-deoxyguanosine (2'NDG), previously reported by us to effectively treat acute herpes simplex infections in mice, was used therapeutically to significantly enhance healing of established herpetic corneal lesions and prevent stromal disease in rabbits. Treatment using 0.06% 2'NDG drops (5 times daily) starting 3 days after infection resulted in more rapid healing of corneal epithelial lesions, rapid resolution of conjunctival inflammation, and prevention of stromal clouding compared to placebo-treated animals. In comparative dose-response titrations, the relative potency of 2'NDG to acyclovir was 6.4, which was significant. In addition, soluble ophthalmic inserts were developed for delivery of 2'NDG. Once a day treatment using ophthalmic inserts which released 100 micrograms 2'NDG significantly enhanced corneal and conjunctival healing and prevented stromal disease; 2'NDG eye drops (100 micrograms) delivered once a day were also effective in inhibiting the progression of corneal lesions. These results indicate that 2'NDG may be therapeutically effective in treatment of herpes keratitis, and further suggest that for use as eye drops or in an ophthalmic insert, 2'NDG may be effective even if applied once per day.

Dissolution rate studies of compression-molded units made from hydroxypropyl cellulose films.

Hydroxypropyl cellulose films were prepared by compression molding of three different lots of hydroxypropyl cellulose powder at 149 degrees C, 188 degrees C, and 232 degrees C. Rectangular pieces were cut from these films and viscosity average molecular weight (Mv), degree of orientation, and rate of dissolution were measured. The viscosity average molecular weight (Mv) decreased with increasing processing temperature, while, as expected, the dissolution rate increased. Orientation in the thermoformed units was also evaluated. Correlation of these data with the Mv values suggests that orientation has some controlling influence on the dissolution rate. Because the samples possessing the least orientation were molded at the highest temperature, they also had the lowest Mv due to thermal degradation. Therefore, the effects of molecular weight were not fully separated from orientation effects with regard to control over the dissolution rate.

Initial evaluation of transdermal timolol: serum concentrations and beta-blockade.

The serum concentrations and beta-blockade after dermal application of timolol ointment were evaluated in six healthy men (21-31 years old; 74-82 kg). Two patches (25 cm2) containing placebo and either 30 (n = 2) or 60 mg (n = 4) timolol base were randomly applied to the chest for 30 h. Serial serum concentrations of timolol were measured by a radioligand receptor assay. Bicycle ergometry, at a predetermined workload, was performed before and at 3, 8, 24, and 48 h after patch application; mean +/- SD heart rates (beats/min) at these times were 167 +/- 2, 158 +/- 7, 125 +/- 7, 120 +/- 5, and 150 +/- 5 (last 3 values: p less than 0.05 from pretreatment), and beta-blockade was evident in all subjects. Measurable serum concentrations in the therapeutic range were achieved in all subjects. The change in exercise-induced heart rate (y) was closely related to log timolol serum concentration (x) (y = -36 X - 5.3; r = -0.92; p less than 0.001). Based on the amount of timolol in the residual ointment, 50-60% of the original timolol dosage was delivered from the patch. Skin irritation under the patch compared with placebo was minimal. Further studies are warranted to assess the potential clinical utility of transdermal timolol.

Efficacy of 2'-nor-2'-deoxyguanosine treatment for orofacial herpes simplex virus type 1 skin infections in mice.

2'-Nor-2'-deoxyguanosine (2'NDG), a new antiviral agent, conferred protection when given orally or topically to hairless mice after the mice were subjected to orofacial infection with herpes simplex virus type 1. The average severity of orofacial lesions was significantly reduced in mice receiving oral gavage treatments twice daily for 7 days beginning 3 h postinfection. The minimum effective dose of 2'NDG was 0.2 mg/kg per day. A minimum of eight treatments over 4 days resulted in a significant reduction in lesion severity. Topical treatment begun 3 h postinfection and continued four times daily for 3 days resulted in a minimum effective dose of 0.06%. Oral treatment with 2'NDG begun as late as 72 h postinfection or topical treatment begun as late as 48 h postinfection resulted in significantly reduced lesion severity compared with lesion severity among placebo-treated animals. In addition, significant prevention of ganglionic infection occurred when 2'NDG was administered either orally or topically within 24 h after infection.

Bioavailability assessment under quasi- and nonsteady-state conditions III: Application.

The applicability of bioavailability assessment at quasi- and nonsteady state is illustrated with data from a study comparing two formulations of amitriptyline hydrochloride in humans. Relative bioavailability as a function of the observed mean plasma concentrations may be expressed in closed form, provided the affected intervals begin and end in the log-linear region. Alternatively, numerical, graphical and/or electronic computational techniques may be used to stimulate the appropriate [Cp(i)]sim, the proximity of which to [Cp(i)]obs is a function of relative bioavailability and omega. If a model can be found to fit the data adequately, it would be sufficient that only one sampled interval end in the log-linear phase.

Bioavailability assessment under quasi- and nonsteady-state conditions. I: theoretical considerations.

A strategy was devised to permit bioavailability estimations at quasi- and nonsteady states. The proposed method retains most attributes of a steady-state comparison without being burdened by its protractiveness. The only necessary requirements are that drug disposition obeys linear kinetics and that succeeding doses are administered during the log-linear phase free from the influence of continuing absorption.