Development and evaluation of topical formulations that contain hydroethanolic extract from Schinus terebinthifolia against HSV-1 infection

Abstract The therapeutic drugs to treat Herpes simplex virus (HSV) infections have toxic side effects and there has been an emergence of drug-resistant strains. Therefore, the search for new treatments for HSV infections is mounting. In the present study, semi-solid formulations containing a crude hydroethanolic extract (CHE) from Schinus terebinthifolia were developed. Skin irritation, cutaneous permeation, and in vivo therapeutic efficacy of the formulations were investigated. Treatment with the ointment formulations did not result in any signs of skin irritation while the emulsions increased the thickness of the epidermis in Swiss mice. The cutaneous permeation test indicated that the CHE incorporated in the formulations permeated through the skin layers and was present in the epidermis and dermis even 3 h after topical application. In vivo antiviral activity in BALB/c mice treated with the CHE ointments was better than those treated with the CHE emulsions and did not significantly differ from an acyclovir-treated group. Taken together, this suggests that the incorporation of CHE in the ointment may be a potential candidate for the alternative topical treatment of herpetic lesions.

The effect of chitosan on the bioaccessibility and intestinal permeability of acyclovir.

Chitosan is object of pharmaceutical research as a candidate permeability enhancer. However, chitosan was recently shown to reduce the oral bioavailability of acyclovir in humans. The effect of chitosan on two processes determining the oral bioavailability of acyclovir, bioaccessibility and intestinal absorption, was now investigated. Acyclovir's bioaccessibility was studied using the dynamic TNO gastro-Intestinal Model (TIM-1). Four epithelial models were used for permeability experiments: a Caco-2 cell model in absence and presence of mucus and both rat and porcine excised intestinal segments. Study concentrations of acyclovir (0.8 g/l) and chitosan (1.6 g/l and 4 g/l) were in line with those used in the aforementioned human study. No effect of chitosan was measured on the bioaccessibility of acyclovir in the TIM-1 system. The results obtained with the Caco-2 models were not in line with the in vivo data. The tissue segment models (rat and porcine intestine) showed a negative trend of acyclovir's permeation in presence of chitosan. The Ussing type chamber showed to be the most biopredictive, as it did point to an overall statistically significantly reduced absorption of acyclovir. This model thus seems most appropriate for pharmaceutical development purposes, in particular when interactions between excipients and drugs are to become addressed.

ß-l-1-[5-(E-2-bromovinyl)-2-(hydroxymethyl)-1,3-(dioxolan-4-yl)] uracil (l-BHDU) prevents varicella-zoster virus replication in a SCID-Hu mouse model and does not interfere with 5-fluorouracil catabolism.

The alphaherpesvirus varicella-zoster virus (VZV) causes chickenpox and shingles. Current treatments are acyclovir (ACV) and its derivatives, foscarnet and brivudine (BVdU). Additional antiviral compounds with increased potency and specificity are needed to treat VZV, especially to treat post-herpetic neuralgia. We evaluated ß-l-1-[5-(E-2-bromovinyl)-2-(hydroxymethyl)-1,3-(dioxolan-4-yl)] uracil (l-BHDU, 1) and 5'-O-valyl-l-BHDU (2) in three models of VZV replication: primary human foreskin fibroblasts (HFFs), skin organ culture (SOC) and in SCID-Hu mice with skin xenografts. The efficacy of l-BHDU in vivo and its drug-drug interactions were previously not known. In HFFs, 200µM l-BHDU was noncytotoxic over 3days, and l-BHDU treatment reduced VZV genome copy number and cell to cell spread. The EC50 in HFFs for l-BHDU and valyl-l-BHDU were 0.22 and 0.03µM, respectively. However, l-BHDU antagonized the activity of ACV, BVdU and foscarnet in cultured cells. Given its similar structure to BVdU, we asked if l-BHDU, like BVdU, inhibits 5-fluorouracil catabolism. BALB/c mice were treated with 5-FU alone or in combination with l-BHDU or BVdU. l-BHDU did not interfere with 5-FU catabolism. In SCID-Hu mice implanted with human skin xenografts, l-BHDU and valyl-l-BHDU were superior to ACV and valacyclovir. The maximum concentration (Cmax) levels of l-BHDU were determined in mouse and human tissues at 2h after dosing, and comparison of concentration ratios of tissue to plasma indicated saturation of uptake at the highest dose. For the first time, an l-nucleoside analog, l-BHDU, was found to be effective and well tolerated in mice.

[Inhibition of the reproduction of strains of the herpes simplex virus type 1 with drug resistance]. / Ingibirovanie reproduktsii shtammov virusa gerpesa prostogo tipa 1 s lekarstvennoi ustoichivost'iu.

Inhibition of type-1 herpes simplex strains resistant to acyclovir, phosphonoacetic acid and their combination by combined use of three drugs with different mechanisms of action capable of suppressing reproduction of the acyclovir resistant strain was studied. The combinations used were the following: Ara-A + ribavirin + phosphonoformic acid, Xylo-A + ribavirin + phosphonoformic acid and Ph-ACH + Ara-A + ribavirin. The former two combinations had a synergistic action on the standard strain L2 whose drug susceptibility had not undergone changes as well as on the acyclovir resistant strain. As for the strain resistant to phosphonoacetic acid and to acyclovir + phosphonoacetic acid the effect was additive. Ph-ACH + Ara-A + ribavirin had a marked synergistic action on all the strains tested.

Interactions of a nonpeptidic drug, valacyclovir, with the human intestinal peptide transporter (hPEPT1) expressed in a mammalian cell line.

The results of previous work performed in our laboratory using an in situ perfusion technique in rats and rabbit apical brush border membrane vesicles have suggested that the intestinal uptake of valacyclovir (VACV) appears to be mediated by multiple membrane transporters. Using these techniques, it is difficult to characterize the transport kinetics of VACV with each individual transporter in the presence of multiple known or unknown transporters. The purpose of this study was to characterize the interaction of VACV and the human intestinal peptide transporter using Chinese hamster ovary (CHO) cells that overexpress the human intestinal peptide transporter (hPEPT1) gene. VACV uptake was significantly greater in CHO cells transfected with hPEPT1 than in cells transfected with only the vector, pcDNA3. The optimum pH for VACV uptake was determined to occur at pH 7.5. Proton cotransport was not observed in hPEPT1/CHO cells, consistent with previously observed results in tissues and Caco-2 cells. VACV uptake was concentration dependent and saturable with a Michaelis-Menten constant and maximum velocity of 1.64 +/- 0.06 mM and 23.34 +/- 0.36 nmol/mg protein/5 min, respectively. A very similar Km value was obtained in hPEPT1/CHO cells and in rat and rabbit tissues and Caco-2 cells, suggesting that hPEPT1 dominates the intestinal transport properties of VACV in vitro. VACV uptake was markedly inhibited by various dipeptides and beta-lactam antibiotics, and Ki values of 12.8 +/- 2.7 and 9.1 +/- 1.2 mM were obtained for Gly-Sar and cefadroxil at pH 7.5, respectively. The present results demonstrate that VACV is a substrate for the human intestinal peptide transporter in hPEPT1/CHO cells and that although transport is pH dependent, proton cotransport is not apparent. Also, the results demonstrate that the hPEPT1/CHO cell system has use in investigating the transport kinetics of drugs with the human intestinal peptide transporter hPEPT1; however, the extrapolation of these transport properties to the in vivo situation requires further investigation.

[Verrucous herpes zoster in AIDS patients]. / Herpes zoster verrucoso em doentes com SIDA.

The authors describe a case of disseminated Herpes-Zoster (VZV) in an HIV 1 positive patient with AIDS. Hyperkeratotic characteristics, acyclovir resistance and sensitivity to foscarnet of cutaneous lesions are the most important features of this example. From the casuistics of the department, the authors describe two similar cases and review the medical literature with emphasis on etiopathogenic, diagnostic and therapeutic factors of lesions caused by DNA Virus in immunocompromised hosts.

AZT: farmacologia, benefícios e aplicaçÆes clínicas / AZT: pharmacology, general considerations and clinical effects

Este trabalho consiste numa revisåo dos principais tópicos referentes ao uso do AZT, como histórico, consideraçÆes gerais, mecanismo de açåo, farmacocinética, uso terapêutico e efeitos clínicos, reaçÆes adversas e interaçÆes medicamentosas. Pretender uma introduçåo para a descriçåo de nossa experiência com a droga, através de dois grupos de pacientes, 40 no total, a ser publicada num futuro próximo

Effect of a thymidine kinase inhibitor (L-653,180) on antiviral treatment of experimental herpes simplex virus infection in mice.

Thymidine kinase (TK) inhibitors can block the activity of TK-dependent antiviral drugs in vitro. We have examined the ability of the TK inhibitor (+/-)-9-([(Z)-2-(hydroxymethyl)cyclohexyl] methyl)guanine (L-653,180) to prevent the therapeutic effect of acyclovir (ACV) in experimental herpes simplex virus type 1 (HSV) skin infections of mice. The results showed that ACV given in the drinking water prevents, in a dose-dependent way, the evolution of the viral infection, and that L-653,180 can reverse some of the therapeutic effects of the antiviral drug. Among the parameters used to evaluate the effect of the TK inhibitor mortality was increased compared to ACV treatment alone, only in the presence of low doses of ACV, whereas the establishment of latent infections in sensory ganglia was significantly increased compared to ACV treatment alone, even when high doses of ACV were administered together with L-653,180.