Ethiop. pharm. j. Page 15 PERFORMANCE EVALUATION OF TOPICAL FORMULATIONS OF THE CRUDE EXTRACTS OF L. ADOENSIS AND O. ROCHETIANA Hailu Tadeg 1 , Endris Mohammed 2 , Kaleab Asres3 and Tsige Gebre-Mariam1* ABSTRACT: Lippia adoensis and Olinia rochetiana are traditionally used in the form of topical applications for the treatment of various skin disorders in Ethiopia. In view of their traditional uses and proven antimicrobial activities, the crude extracts of the two botanicals were incorporated into various formulation bases having different degrees of hydrophilicity and/or lipophilicity. The performances of the resulting topical formulations were then evaluated using agar well diffusion technique. The results indicated that water miscible (hydrophilic) formulations are superior in performance to water immiscible (hydrophobic) ones. The most lipophilic ointment (petrolatum ointment) showed virtually no activity indicating that the active compound(s) of the herbal drugs could not be released from this formulation. Some formulations of the herbal drugs showed relatively comparable activities with different topical antiseptic products locally available in the market. L. adoensis in sodium laurate monostearin cream base showed a zone of inhibition of 25+0.9 against S. aureus, which is even better than that of gentamycin (21+1.0) against the same organism. Similarly, O. rochetiana, in the same base, showed a zone of inhibition of 65+2.5 against T. menthagrophytes, which is by far better than any of the topical antifungal agents tested. From among the marketed topical antifungal agents clotrimazole gave the maximum zone of inhibition (47+2.5. The traditional claims attributed to these herbal drugs by the local people for the treatment of topical skin disorders is partly justified by the different degrees of antimicrobial activities exhibited by topical formulations of these botanicals against the selected strains of bacteria and fungi which are known to be common causative agents for different types of skin infections. Key words: Lippia adoensis, Olinia rochetiana, Topical formulations, Performance evaluation, Antimicrobial activity INTRODUCTION Skin diseases are highly prevalent throughout the world. Inflammatory disorders are common in developed countries while infectious diseases predominate in developing countries (1). Different studies (2-7) indicate that skin disorders, particularly of the 1 Department of Pharamceutics, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia 2 Department of Microbiology, Ethiopian Health and Nutrition Research Institute, P.O. Box 1242, Addis Ababa, Ethiopia 3 Department of Pharmacognosy, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia *Correspondence Page 16 Vol. 22, 2004 infectious type, are highly prevalent in Ethiopia. Given the HIV/AIDS pandemic in the country and its association with various skin disorders (8-10), it is likely that it will continue to affect a significant segment of the population. Since the majority of Ethiopians, particularly the rural poor, have limited access to conventional drugs, traditional medicines could play a great role in curbing this problem. The traditional practice of topically treating dermatological conditions with plantderived therapeutic preparations predates the cultures of ancient civilization and remains vital today in our life (11). Alternative therapies are becoming increasingly popular, particularly among patients with chronic skin disorders such as eczema, which are not cured by standard treatments (12). With the growing interest in alternative and complementary therapies, clinical and collected observational studies are being made in order to help define specific indications for choice of herbal treatment based on both the skin disorder and the unique characteristics of the patient involved (13). Many scientific studies show that plants possess a vast complex arsenal of phytochemicals that calm, restore and heal the skin. At the simplest level, soothing and emollient herbal remedies are found to contain mucilage, polysaccharides, complex sugars and starch derivatives that relieve dryness, and provide soothing to membranes that cover the skin. Protection of the skin hydration is achieved using seed oils rich in fatty acids and triglycerides that reduce the transepidermal water loss and increase skin hydration. It is known that those plants with anti-inflammatory properties often have a high level of flavonoids; those that are used to firm and tone the skin are rich in tannins and those that have cicatrizing and vulnerary properties often have a high level of plant sterols. Often the skin healing is compromised by opportunistic infections and in these cases the use of plants can provide a complex array of antimicrobial and antifungal biocides (14). Research on the bioactivity of tropical medicinal plants has demonstrated that most are safe and effective therapies. Tropical rural communities, have poor access to modern pharmaceuticals due to their high cost. Therefore, locally available medicinal plants can contribute to health care needs and also to generate economic benefits for tropical rural communities. The WHO Traditional Medicine Pogramme and other research programmes have conducted various researches on tropical medicinal plants and the results have demonstrated safety and efficacy for the treatment of common tropical diseases including malaria and infections of the skin, lungs and gastrointestinal tract (15). Therefore, the wise and scientific use of these resources can contribute to the health of large number of the rural community in these areas that have limited or no access to modern health care. L. adoensis (locally known as “Kesse”) and O. rochetiana (locally known as “Tife”) are among the most commonly used herbal drugs in Ethiopian traditional medicine (either as powder, infusion or in the form of ointment) for the treatment of various skin diseases including eczema, acne, scabies and superficial microbial infections (16-18). The crude extracts of these plants are also shown to have antimicrobial activities (19). In this study, the hydroalcoholic extracts of these two plants were formulated into creams and Ethiop. pharm. j. Page 17 ointments having different degrees of hydrophiliciy/lipophilicity, and the performance of the resulting topical formulations was assessed. MATERIALS AND METHODS Chemicals: Glyceryl monostearate, cetostearyl alcohol, Cetomacrogol 1000 BPC, polyethylene glycol 4000 (all from BDH Chemicals Ltd., England), sodium lauryl sulphate (AVONCHEM Ltd., UK), Liquid Paraffin BP (Germany), Petrolatum white, USP (Ethiopian Pharmaceutical Manufacturing, Addis Ababa, Batch No. 101087-1), polyethylene glycol 400 (Sigma-Aldrich Chemie GMBH, Germany), were all used as received. Media: The microbial growth media nutrient agar (DEFCO Laboratories, USA), peptone bacteriological (BDH Chemicals Ltd., England), tryptone soya broth and Sabauraud dextrose agar (both from OXOID Ltd., England), yeast extract (UNIPATH Ltd., England) and sodium chloride (East Anglia Chemicals, United Kingdom) were all obtained from the Department of Microbiology, Ethiopian Health and Nutrition Research Institute (EHNRI). Test strains: The test organisms including Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853), all American Type Culture Collections, were obtained from the Department of Microbiology, Ethiopian Health and Nutrition Research Institute (EHNRI). Aspergillus niger (ATCC 10535), Trichophyton mentagrophytes (ATCC 18748), all American Type Culture Collections, and Candida albicans (clinical isolate) were obtained from the Department of Drug Research, Ethiopian Health and Nutrition Research Institute (EHNRI). Commercial topical antimicrobial products: The topical antibacterial and antifungal products namely Faban® ointment (2% sodium fusidate, HOE Pharmaceuticals, Lot No. 01021015, Malaysia), Bactroban® ointment (2% mupirocin, Smith Kline Beecham Pharmaceuticals, Batch No 2352/040818, England), Tetracycline hydrochloride ointment, USP (3% tetracycline, Ambalai Sarabhai Enterprise Ltd., Batch No 02JUL1, India), Faban® cream (2% fusidic acid, HOE Pharmaceuticals, Lot No 649A0005, Malaisia), Sagestan® topical cream (0.1% gentamycin PT SANBE FARMA, Batch No BA355, Indonesia), Dazor® cream (2% ketoconazole, HOE Pharmaceuticals, Lot No. 51282015, Malaysia), Ketoral® cream (2% ketoconazole, BİLİM PHARMACEUTICALS, Lot No. 0202003, Turkey), Kenazol® cream (2% ketoconazole, DOMINA PHARMACEUTICALS, Lot. No. 83, Syria), Fungoral® cream (2% ketoconazole, İLAN İLTAS FabricasI, Batch No. 9011610, Turkey), Clotri-Denk® cream (1% clotrimazole, Denk Pharma, Batch/Lot. No. 11880, Germany), Sha Hsein Ghin® cream (1% clotrimazole, SHANGHAI MEDICINES & HEALTH PRODUCTS Import and Export Corporation, Batch No. JW02C01, China), Nizoral® cream (2% ketoconazole, JANSSEN Pharmaceutical Ltd., Lot No. 430BA, Page 18 Vol. 22, 2004 South Africa), Canesten® cream (1% clotrimazole, Bayer, Batch No. BXB55S1, Germany) were all purchased from local markets in Addis Ababa. Methods Formulation of the herbal drugs and in vitro evaluation of their performance: Topical formulations of the crude extracts of the two herbal drugs (L. adoensis and O. rochetiana) were prepared at strength of 10% using five different formulation bases (Table 1). Preparation of the bases: The formulation bases were prepared manually by melting the fatty phases at 70 oC over a water bath and stirring continuously to room temperature in the case of anhydrous bases. In preparing hydrous vehicles, the aqueous phase was also heated to 70 oC and added to the melted fatty phase and stirred continuously to room temperature. PEG ointment was prepared by heating the two ingredients on a water bath to about 65 oC and then allowing the mixture to cool with continuous stirring until congealed. These bases were then used immediately for the preparation of topical products of the herbal drugs. Preparation of the topical formulations: The crude extracts of the two herbal drugs (L. adoensis and O. rochetiana) were separately incorporated into the already prepared vehicles (formulation bases) while cold by levigation method. The crude drug was finely powdered in a mortar and then mixed with an equal amount of the base and levigated on an ointment slab until a smooth gritfree mixture was obtained. The rest of the base was then added in gradual increments. The strength of the final product was made to be 10% by incorporating 2 g of the powdered crude extract in 18 g of the respective bases to get 20 g of the final product. The resulting preparation was finally packed into an ointment jar and stored at room temperature until it was repacked into a syringe for performance evaluation study. In vitro performance evaluation of the topical formulations: The performances of topical formulations of the crude extracts of the two herbal drugs were evaluated using the agar well diffusion technique (20). Sterilized and cooled nutrient agar (40 ml) were added to a sterile petridish and allowed to solidify. Equidistant holes were made on to the agar plates by the use of a sterile cork borer. Following removal of the agar plugs, the designated topical agents were added to each well until full (approximately equal to 0.1 ml or ≈ 0.2 g) by means of a 5 ml syringe. A volume of 20 ml of nutrient agar (which was previously melted and maintained at 50 oC) was inoculated with 0.5 ml of a microbial suspension equivalent to 0.5 McFarland standard. The broth suspension of the organisms was thoroughly mixed in an agitator and poured onto the previously prepared test plates containing the antimicrobial topical formulations. After solidification of the agar, the plates were inverted and incubated at 37 oC for 18 to 24 h. The magnitude of susceptibility of the respective organisms was determined by measuring the diameter of the zones of inhibition in mm (including the diameter of the wells) around each well containing the topical antimicrobial agents. Ethiop. pharm. j. Page 19 Performance evaluation of the formulations against fungi was carried out in the same way mentioned above using Sabauraud dextrose agar as a growth media. The plates were incubated at 25 oC for 3 to 7 days and the resulting zones of inhibition were recorded accordingly. In addition to the stated herbal formulations, the formulation bases (vehicles) and different commercial topical antiseptics available in the market with different brands (Table 2) including gentamycin and ketoconazole were tested in the same manner as above serving as negative and positive controls, respectively. Table 1. List of formulation bases and their compositions used as vehicles for the preparation of topical formulations of L. adoensis and O. rochetiana Code no Base 1 Name of the base Sodium laurate monostearin cream base Base 2 Macrogol cream base Base 3 Gibson ointment base Base 4 PEG ointment base Base 5 White petrolatum ointment base Components of the base Glyceryl monostearate Sodium lauryl sulfate Cetostearyl alcohol Liquid paraffin Water to Cetomacrogol emulsifying wax BP Liquid paraffin White petrolatum Water Sodium lauryl sulfate Cetyl alcohol White soft paraffin Water PEG 4000 PEG 400 White petrolatum Proportions (in percent) 5 3 2 25 100 9 6 15 70 1 16 40 43 40 60 100 RESULTS AND DISCUSSION The results of the evaluation studies (Table 3) indicate that water miscible (hydrophilic) formulations are superior in performance to the water immiscible (hydrophobic) ones. In other words, while Formulations 1 to 4 (Table 3) showed different degrees of activities against the tested strains of organisms, Formulation 5, which was the most lipophilic ointment, showed virtually no activity indicating that the active component(s) of the herbal drugs could not be released from this formulation to the media thus failing to inhibit the growth of microorganisms surrounding the point of application. The performance profile of the formulations was therefore found to be influenced by the type Page 20 Vol. 22, 2004 Table 2. Topical antibacterial and antifungal products used as positive controls during the performance evaluation of topical formulations. Code no 1 2 3 4 5 1 2 3 4 5 6 7 8 Product name Antibacterial Products ® Faban ® Bactroban Tetracycline Hydrochloride ® Faban ® Sagestan Antifungal Products ® Dazor ® Ketoral ® Kenazol ® Fungoral ® Clotri-Denk ® Sha Hsein Ghin ® Nizoral ® Canesten Source country Antimicrobial substance Concentration Bases Malaysia England India Sodium fusidate Mupirocin Tetracycline 2% 2% 3% Ointment Ointment Ointment Malaysia Indonesia Fusidic acid Gentamycin 2% 0.1% Cream Cream Malaysia Turkey Syria Turkey Germany China South Africa Germany Ketoconazole Ketoconazole Ketoconazole Ketoconazole Clotrimazole Clotrimazole Ketoconazole Clotrimazole 2% 2% 2% 2% 1% 1% 2% 1% Cream Cream Cream Cream Cream Cream Cream Cream and nature of the vehicle (base) into which the drugs were incorporated. In general, all formulations containing water as one of the components of the vehicle showed some degree of activity, the strength of the activity being directly related to the degree of hydrophilicity of the vehicle. Similarly, from among one-phase systems (i.e. ointments), the water-soluble ointment (Formulation 4) was found to have better activity profile than the hydrophobic ointment (Formulation 5). All the above results indicate that the release of the medicinally active component(s) from the hydrophilic bases is more intensive than from the lipophilic bases. The results obtained in the current study are in agreement with those of other studies conducted using the same model or other models that utilize membrane systems. The release of indomethacin, chloramphenicol, acetyl salicylic acid and neomycin sulfate from hydrophilic bases was found to be faster than from lipophilic bases (21). Similarly, ocimum oil in lipophilic semisolid bases exhibited much lower or no antibacterial activity compared to its formulation in the more hydrophilic macrogol blend ointment (20). The sensitivity pattern of the microorganisms to the formulations indicated that E. coli was the least responding organism from among bacteria and C. albicans from among the fungi employed in the test. Formulation 1 was found to have the highest activity profile against all the tested strains. However, the base of this formulation showed activity against S. aureus (17+0.4) and T. mentagrophytes (29+2.5). Expectedly, the increased activity of this formulation was attributed to the additional activity exerted by the vehicle itself. Ethiop. pharm. j. Page 21 Table 3. Antimicrobial activity profiles of topical formulations of crude extracts and the formulation bases (negative controls). Test sample Code no Zone of inhibitions (mm) Bacterial strains Fungal strains Sa Ec Pa Ca Tm 10% L. adoensis in: 15+0.8 14+1.2 NT 38+1.8 Base 1 Formn. 1 25+0.9 Base 2 Formn. 2 16+0.5 13+1.0 NT 29+1.2 Base 3 Formn. 3 13+0.5 14+0.9 NT 18+1.5 Base 4 Formn. 4 16+1.0 15+1.0 NT 15+1.0 Base 5 Formn. 5 NT 10% O. rochetiana in: 13+0.3 14+0.6 22+1.6 65+2.5 Base 1 Formn. 1 23+0.3 Base 2 Formn. 2 18+1.3 15+0.8 15+1.3 19+2.8 49+2.1 Base 3 Formn. 3 17+0.8 13+0.6 14+1.0 19+2.0 42+3.1 Base 4 Formn. 4 21+1.5 53+3.0 Base 5 Formn. 5 Negative controls (Formulation Bases) Na laurate MSCB Base 1 17+0.4 -29+2.5 Macrogol cream base Base 2 Gibson base Base 3 PEG ointment Base 4 15+1.8 White pet. Ointment Base 5 Formn. = Formulation, MSCB = Monostearin cream base, Pet. = Petrolatum, Sa = S. aureus, Ec = E. coli, Pa = P. aeruginosa, Ca = C. albicans, Tm = T. mentagrophytes, NT = not tested, - = no activity. The antimicrobial activity of Base 1 may be due to the presence of sodium lauryl sulfate as one of the components of the base. Pharmaceutically, sodium lauryl sulfate is used as a protective skin cleaner, having bacteriostatic action against Gram-positive bacteria, and is also used in medicated shampoos (22). Moreover, all fatty acids and their salts are known to have variable fungicidal properties (23). Therefore, the intrinsic antimicrobial property of sodium lauryl sulfate might have contributed to the remarkable antibacterial and antifungal activities of Formulation 1. Formulation 4 of O. rochetiana was shown to have significantly higher activity on T. mentagrophytes compared to the rest of the formulations. Similar trend was observed on its activity against C. albicans. However, this trend was not observed for the same formulation of L. adoensis against T. mentagrophytes. This discrepancy might actually be related to the type and nature of the active components present in each herbal drug that are responsible for the antimicrobial activity. The active components found in O. rochetiana might interact with PEG to yield a more active product or a product that is more diffusible than the active component leading to a higher zone of inhibition. Page 22 Vol. 22, 2004 The consequences of these drug-vehicle interactions have been described in one study (24) that was made to evaluate the release properties of various drugs from different PEG ointment bases. It was indicated that the molecular size, shape and degree of interaction with the incorporated drugs are among the major factors affecting the rate of diffusion of the drugs from these bases. Accordingly, formulation base containing PEG 6000 was found to be the best vehicle for chloramphenicol compared to those formulated using PEG 4000 and PEG 2000. This increase in drug diffusion was reported to be due to direct interaction between chloramphenicol and PEG 6000, which is characterized by more surface tension lowering effect than PEG 4000 and PEG 2000. In the case of neomycin sulfate however, diffusion was more pronounced in the less viscous PEG 2000 compared to PEG 4000 and PEG 6000. It was proposed that neomycin sulfate might interact to some extent with polyethylene glycol macromolecules, and this interaction may affect the extent of drug diffusion. For ampicillin trihydrate, the best release was obtained from preparation containing PEG 400:2000. Since ampicillin is an ionic drug i.e. more hydrophilic, it was expected that higher diffusion would be obtained with the lower molecular weight PEGs. It was also concluded that the more diffusible the PEG/ampicillin complex, the more it diffuses through the agar (24). Although it is difficult to explain variations in the results of this particular study based on pure compounds found in the herbal drugs at this stage, any of the above consequences would be anticipated to operate and hence might be reasons for the discrepancy of the observed results. In another study, the release of ciprofloxacin and tinidazole from PEG (water washable) base was reported to be more than that from lanolin petrolatum (emulsion) base. The antimicrobial activities of the formulation containing PEG was found to be higher than the other formulations (25). In fact, macrogol blend ointment base was also reported to have antibacterial properties (20). It was found to have some degree of antifungal activity in this study as well on at least T. mentagrophytes (15+1.8). The exceptionally higher antifungal activity of this formulation might therefore be linked to the inherent activity of the blend base or the synergistic or potentiation of antimicrobial activity it imparts upon the active drug. On the contrary, Formulation 4 of O. rochetiana has shown no antibacterial activities against both Gram-negative and Gram-positive bacterial strains. This result in fact seems to negate the above argument. Since crude drugs may contain diversified types of compounds with complex chemical nature, the above discrepancy might be due to the presence of compound(s) having good antifungal properties but no antibacterial properties. Macrogol ointment bases are known to be incompatible with a range of chemicals including phenols, sorbitol, tannic acid, etc. These bases are also known to reduce the antimicrobial activity of quaternary ammonium compounds and methyl and propyl p-hydroxybenzoates. They are also reported to rapidly inactivate penicillin and bacitracin (26). Ethiop. pharm. j. Page 23 Therefore, the lack of antibacterial activity of O. rochetiana formulated in macrogol ointment base might be due to the inactivation of the active compound(s) responsible for the antibacterial activity through interaction with the base which might lead to the formation of an inactive compound or a complex that fails to diffuse through the agar media. Compared to the positive controls (Table 4), i.e. topical antimicrobial products marketed for the treatment of different topical skin infections, some formulations of the studied drugs studied (L. adoensis and O. rochetiana) have shown relatively comparable activities. For instance, Formulation 1 of both herbal drugs at a concentration of 10% showed activity against S. aureus comparable to that of gentamycin cream. Similarly, Formulations 1 and 4 of O. rochetiana at the same concentration showed by far better activity profile than all the marketed topical antifungal agents (Table 5) against T. mentagrophytes. Table 4. Antibacterial activity profiles of the marketed topical antibacterial agents in comparison with some formulations of the crude extracts. Code No Antimicrobial substance Concentration Base type Sa Zone of inhibitions Ec Pa 1 Sodium fusidate 2% Ointment 41+0.5 2 Mupirocin 2% Ointment 57+3.1 30+0.9 3 Tetracycline HCl 3% Ointment 43+2.1 33+0.6 4 Fusidic acid 2% Cream 37+1.7 5 Gentamycin 0.1% Cream 21+1.0 23+1.5 Form. 1 L. adoensis 10% Cream 25+0.9 15+0.8 Form. 4 L. adoensis 10% Ointment 16+1.0 Form. 1 O. rochetiana 10% Cream 23+0.3 13+0.3 15+0.8 Form. 2 O. rochetiana 10% Cream 18+1.3 Form. = Formulation, Sa = S. aureus, Ec = E. coli, Pa = P. aeruginosa, - = no activity 16+1.2 19+1.0 24+0.3 14+1.2 15+1.0 14+0.6 15+1.3 The higher performance of the marketed antimicrobial products over some of the strains, for example, mupirocin and tetracycline on bacterial strains and ketoconazole and clotrimazole on C. albicans may even be related to the type of bases used to incorporate the designated drugs in addition to the active components. Because, some components of topical vehicles like sodium lauryl sulfate, possess certain degree of antimicrobial activities as described previously. Cationic surfactants, which are commonly used as components of topical products, are also known to exert a bactericidal action against a broad spectrum of Gram-positive and Gram-negative bacteria. They are also active against several pathogenic species of fungi and protozoa. For example, benzalkonium chloride is employed as antiseptic for application to the skin, mucous membranes, burns and wounds (22,23,27). Besides, topical preparations, particularly those containing water are known to contain a preservative in order to prevent microbial growth and spoilage of the product (28). Many of the marketed topical formulations might as well contain preservatives, and this by itself might contribute to the overall antimicrobial activity of the marketed products. Page 24 Vol. 22, 2004 The herbal formulations, on the other hand, did not have any preservative included in the vehicle indicating that the reported activity is merely due to the inherent potential of these herbal products to kill or inhibit the growth of bacteria and fungi. Table 5. Antifungal activity profiles of the marketed topical antifungal agents in comparison with some formulations of the crude extracts. Code No Antimicrobial substance ® Concentration Base type Zone of inhibitions Ca Tm 1 Ketoconazole 2% Cream 44+0.7 ® 2 Ketoconazole 2% Cream 48+4.8 ® 3 Ketoconazole 2% Cream 45+2.0 ® 4 Ketoconazole 2% Cream 43+3.5 ® 5 Clotrimazole 1% Cream 45+2.5 ® 6 Clotrimazole 1% Cream 44+4.0 ® 7 Ketoconazole 2% Cream 45+1.5 ® 8 Clotrimazole 1% Cream 51+2.6 Formn. 1 L. adoensis 10% Cream NT Formn. 2 L. adoensis 10% Cream NT Formn. 1 O. rochetiana 10% Cream 22+1.6 Formn. 2 O. rochetiana 10% Cream 19+2.8 Formn. 4 O. rochetiana 10% Ointment 21+1.5 Formn. = Formulation, Ca = C. albicans, Tm = T. mentagrophytes, - = no activity, NT = not tested. 27+1.3 31+1.5 30+0.5 30+2.0 47+2.5 39+2.5 31+0.9 31+1.3 38+1.8 29+1.2 65+2.5 49+2.1 53+3.0 CONCLUSION The overall results of this study have clearly indicated that the rate and degree of release and hence the activity or performance of a given drug may be modulated by the type and nature of the formulation. Therefore, in order to optimize the performance of the product, the choice of formulation should be based on whether or not the formulation delivers the drug at the target site so as to achieve the desired therapeutic concentration. A formulation that fails to release the drug to the required extent is likely to be ineffective. Therefore, the rational selection of the formulation bases is of paramount importance in optimizing the performance of topical preparations of herbal products. By and large, the findings of this study suggest that L. adoensis and O. rochetiana may be considered as useful natural alternative therapy for patients with topical infectious skin disorders either alone or in combination with other suitable antimicrobial agents. Further in-depth investigations on such herbal drugs with the aim of isolating the active compounds, toxicity studies and optimizing the formulation for topical delivery are therefore justified. Ethiop. pharm. j. 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