Impact of low abundance HIV variants on response to ritonavir-boosted atazanavir or fosamprenavir given once daily with tenofovir/emtricitabine in antiretroviral-naive HIV-infected patients

Population genotyping (PG) can underestimate resistance if resistance-containing low abundance variants go undetected. PG and clonal analysis (CA) results were compared in virologic failures (VFs) from a 48-week clinical trial that evaluated once-daily fosamprenavir/ritonavir (FPV/r) 1400 mg/100 mg or atazanavir/ritonavir (ATV/r) 300 mg/100 mg, each combined with tenofovir/emtricitabine, in antiretroviral-naive patients. VF was defined as confirmed HIV-1 RNA > or =400 copies/ml at > or =24 weeks or viral rebound >400 copies/ml any time following viral suppression. All patients had baseline PG. One hundred and six patients enrolled (53/arm). Baseline resistance mutations were more prevalent in patients receiving FPV/r (10/53) than ATV/r (3/53). Seven patients (7%) were VFs-four on FPV/r and three on ATV/r. In the four FPV/r-treated VFs, baseline HIV TAMs combinations and/or PI mutations were detected in one by PG at VF (RT: L210W + T215C; PR: M46I + L76V) and three others by CA alone (RT: L210W + T215Y; RT: M41L; RT: K65R + K70R; PR: I47V); all four had study drug-associated mutations (CA detecting more HIV-1 resistance mutations than PG). In the three ATV/r VFs, no baseline drug-associated mutations were detected by PG; for one patient CA detected RT: K65R; PR: I84V. Phylogenetic analysis revealed tight clustering for FPV/r-treated VFs with highly related clones, whereas HIV-1 from ATV/r-treated VFs had no outgrowth from baseline of low abundance resistance-containing variants. In conclusion, low-abundance HIV resistance-containing variants were detected in baseline samples from patients with VF. The archived viruses that reemerged under selection pressure and acquired additional mutations were found primarily in patients in the FPV/r arm. Despite this and a baseline resistance imbalance between the two arms, FPV/r and ATV/r provided similar virologic suppression through 48 weeks; however, these findings highlight the necessity for the development of quick and inexpensive methods for detection of minority species to better guide therapy selection.

Overlap/switch to adefovir monotherapy for lamivudine-resistant patients who responded to combination therapy: a pilot controlled study

OBJECTIVE

The aim of this study was to investigate the outcome of overlap/switch to adefovir dipivoxil (ADV) monotherapy for chronic hepatitis B (CHB) patients with lamivudine (LAM)-resistant HBV, who responded to LAM plus ADV combination therapy.

METHODS

In 29 of 35 LAM-resistant CHB patients, serum HBV-DNA levels decreased to <3.7 log genome equivalent (LGE)/mL at 12 months after LAM plus ADV combination therapy, defined as complete virological response (CVR). The 29 CVR patients were randomly allocated to continuation of combination therapy or switch to ADV monotherapy within 12 months. The cumulative rates of sustained CVR were compared between the two groups.

RESULTS

The follow-up duration after randomization was 19.3-36.7 months (median, 28.2 months) for the combination group and 21.0-36.4 months (29.0 months) for the overlap/switch group. The cumulative rate of sustained CVR during the follow-up period was 100% in all patients of both groups. The total medical expenses during follow-up after randomization were median US$20,949 for the combination group and US$16,107 for the overlap/switch group (p=0.012). Overlap/switch to ADV monotherapy sufficiently repressed the replication of LAM-resistant mutants without the development of ADV-resistant mutants. The rate of sustained CVR was not influenced by treatment regimen (continuation of combination therapy or switching to ADV monotherapy), the duration of the overlap period, or patient and virological characteristics.

CONCLUSION

In LAM-resistant CHB patients who achieved CVR to LAM plus ADV combination therapy, CVR was maintained after overlap/switch to ADV monotherapy, suggesting that it could be a useful regimen for such patients.

[Efficacy and durability of generic adefovir dipivoxil in patients with HBeAg positive chronic hepatitis]

OBJECTIVE

To study the efficacy and durability of generic adefovir dipivoxil (ADV) in patients with HBeAg positive chronic hepatitis.

METHODS

54 nucleosides-naïve patients with HBeAg positive chronic hepatitis were enrolled in this randomized, double-blinded, placebo-controlled, prospective study. 38 patients received ADV (10 mg once daily) and the others received placebo. Then all the patients were treated with ADV for 96 weeks and were followed up for 12 weeks.

RESULTS

(1) At week 12, the level of ALT declined significantly in ADV group(135.84 +/- 10.63 U/L to 58.92 +/- 4.95 U/L, P < 0.001) compared with placebo group (145.56 +/- 17.19 U/L to 159.50 +/- 37.05 U/L) (P < 0.001). The HBV-DNA level also declined significantly in adefovir group compared with placebo group (2.51 vs. 1.04 log10 copies/ml, P < 0.001). (2) The rates of normal ALT, normal of AST and undetectable HBV-DNA at 48 and 96 weeks of therapy with ADV were 63.30%, 70.50%, 87.80%, 88.60%, 53.06%, 54.55%, respectively. (3) There were 17 patients discontinuated ADV after 96 weeks. The follow-up results showed that HBV-DNA became positive again in all these 17 patients and abnormal liver function developed in 88.24% (15/17) patients.

CONCLUSIONS

Treatment of chronic hepatitis B with generic ADV was effective and well tolerated, but relapse may develop when treatment was discontinued.

Segmented polyurethane intravaginal rings for the sustained combined delivery of antiretroviral agents dapivirine and tenofovir

Dual segment polyurethane intravaginal rings (IVRs) were fabricated to enable sustained release of antiretroviral agents dapivirine and tenofovir to prevent the male to female sexual transmission of the human immunodeficiency virus. Due to the contrasting hydrophilicity of the two drugs, dapivirine and tenofovir were separately formulated into polymers with matching hydrophilicity via solvent casting and hot melt extrusion. The resultant drug loaded rods were then joined together to form dual segment IVRs. Compression testing of the IVRs revealed that they are mechanically comparable to the widely accepted NuvaRing IVR. Physical characterization of the individual IVR segments using wide angle X-ray scattering and differential scanning calorimetry determined that dapivirine and tenofovir are amorphous and crystalline within their polymeric segments, respectively. In vitro release of tenofovir from the dual segment IVR was sustained over 30 days while dapivirine exhibited linear release over the time period. A 90 day accelerated stability study confirmed that dapivirine and tenofovir are stable in the IVR formulation. Altogether, these results suggest that multisegment polyurethane IVRs are an attractive formulation for the sustained vaginal delivery of drugs with contrasting hydrophilicity such as dapivirine and tenofovir.

[Budget impact of a set-dose combination of efavirenz-emtricitabine-tenofovir in the treatment of patients infected with HIV-1]

OBJECTIVE

Estimate the budgetary impact of using a set-dose combination of efavirenz-emtricitabine-tenofovir for the Spanish health care system's treatment of patients infected with HIV-1, while evaluating repercussions for each autonomous community in 2008.

METHODS

We developed a budgetary impact model with pharmacological costs for the different currently available treatment options, based on GeSida's recommended guidelines for treating HIV-positive patients. The model defines five possible scenarios in which various possibilities for substituting different drug cocktails with the efavirenz-emtricitabine-enofovir combination are contemplated.

RESULTS

The investment per patient on a national level amounts to euro7,989 in the base scenario (without considering the availability of the efavirenz-emtricitabine-tenofovir combination) and to euro7,997, euro8,424, euro7,830, euro8,375 and euro8,527 for scenario 1 (substitution of recommended drugs with efavirenz, emtricitabine and tenofovir or efavirenz, lamivudine and tenofovir); scenario 2 (substitution of recommended drugs with efavirenz); scenario 3 (substitution of recommended drugs with tenofovir); scenario 4 (substitution of recommended drugs with tenoforvir or zidovudine) and scenario 5 (total substitution), respectively. Compared with the base scenario this means increments of 0.11 %, 5.45 %, -1.99 %, 4.83 % and 6.73 % for scenarios 1, 2, 3, 4 and 5.

CONCLUSION

Use of a set combination of efavirenz, emtricitabine and tenofovir to treat adult patients with the HIV-1 virus would lead to slight surpluses or even budgetary savings by decreasing the number of daily doses, which could increase patients' quality of life and help them stay on the treatment properly.

[The analyse of effectiveness in HBeAg-positive chronic viral hepatitis B treated by adefovir dipivoxil combined with bicyclol]

OBJECTIVE

To analyze the efficacy of adefovir dipivoxil combined with bicyclol in treatment of HBeAg-positive chronic viral hepatitis B (CHB).

METHODS

A total of 91 patients with CHB were randomized into experimental group and control group to be treated. The patients in experimental group (46 samples) received adefovir dipivoxil orally 10 mg daily and bicyclol orally 150 mg daily for 48 weeks and those in control group (45 samples) received adefovir dipivoxil orally 10 mg daily alone for 48 weeks. The serum aminotransferace (ALT/ AST), HBV-DNA, HBeAg/antiHBe were observed before and after treatment.

RESULTS

Compared with pretreatment, the serum aminotransferace were all decreased obviously in two groups, the experimental group is better (P < 0.05). HBVDNA negative conversion rate was significantly higher in experimental group than in the control group (47.8% vs. 31.1%, P < 0.05). There were nostatistically differrence between the two groups in the portion of HBeAg loss rate and HBeAg seroconversion rate. There were no obvious adverse reaction in the study.

CONCLUSION

Adefovir dipivoxil combined with bicyclol is efective in the treatment of chronic hepatitis B.

Acute renal failure in patients with AIDS on tenofovir while receiving prolonged vancomycin course for osteomyelitis

Renal failure developed after a prolonged course of vancomycin therapy in 2 patients who were receiving tenofovir disoproxil fumarate as part of an antiretroviral regimen. Tenofovir has been implicated in the development of Fanconi syndrome and renal insufficiency because of its effects on the proximal renal tubule. Vancomycin nephrotoxicity is infrequent but may result from coadministration with a nephrotoxic agent. Clinicians should be aware that tenofovir may raise the risk of renal failure during prolonged administration of vancomycin.

Salvage therapy with tenofovir followed by adefovir maintenance in a cirrhotic patient with a lamivudine resistant HBV flare

A 36 year old man with chronic hepatitis B and cirrhosis was admitted in our Department for the onset of jaundice, ascites and ALT flare (x 35 u.n.v.) while under lamivudine treatment. Serum HBV-DNA was 1.48 x 10(6) IU/ml and lamivudine (LAM) resistance mutations were present. Tenofovir (TDF) 300 mg/day was added to LAM after its off-label use was authorised. HBV-DNA decreased in a biphasic manner and became undetectable by day 45. A parallel improvement in ALT and bilirubin values was detected. Tenofovir was substituted with adefovir dipivoxil 10 mg/day. Ten months after this switch HBV-DNA remained undetectable. Tenofovir is an effective salvage therapy for critically ill patients with LAM-resistant HBV flares and can be switched to adefovir after HBV-DNA becomes undetectable. Local cost and reimbursement policies are important determinants in antiviral therapy.

Tenofovir: new indication. In chronic hepatitis B: beware bone toxicity

Tenofovir is more effective than adefovir in reducing viraemia in the short term, but with no histological or serological evidence of improvement. It is also associated with a small increase in gastrointestinal disturbances and exacerbation of hepatitis. Its renal and bone risks also need to be closely monitored.

Therapeutic paint of cidofovir/sucralfate gel combination topically administered by spraying for treatment of orf virus infections

The aim of the research was to study a new cidofovir/sucralfate drug product to be used as a spray for treating the mucosal and/or skin lesions. The product, i.e., a water suspension of sucralfate (15% w/w) and cidofovir (1% w/w), combines the potent antiviral activity of the acyclic nucleoside phosphonate cidofovir ((S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine) and the wound healing properties of sucralfate gel (sucrose octasulphate basic aluminum salt). The product was characterized in vitro with respect to compatibility between drug and carrier, spray particle size, spray deposition, drying kinetics, and drug content and release. An interaction between the two active substances was found. The interaction between sucralfate and cidofovir was counteracted by introducing sodium dihydrogen phosphate (16% w/w) in the preparation. The spray formulation containing cidofovir/sucralfate gel painted the skin and dried quickly to a scab, remaining firmly adhered to the lesions. The therapeutic paint was tested in vivo on lambs infected with orf virus by treating the animals with different cidofovir/sucralfate formulations (0.5% or 1% cidofovir + sucralfate 15% + NaH(2)PO(4) 16% w/w) and with sucralfate gel suspension alone as control. The treatment with formulations containing cidofovir and phosphate salt for four consecutive days resulted in a rapid resolution of the lesions, with scabs containing significantly lower amounts of viable virus when compared with untreated lesions and lesions treated with sucralfate suspension alone.

[A study on the treatment of chronic hepatitis B with YMDD mutation]

OBJECTIVE

To explore the strategy for the treatment of chronic hepatitis B with YMDD mutation.

METHODS

A total of 120 chronic hepatitis B patients with YMDD mutation were randomly assigned into four groups. In group A, patients received adefovir dipivoxil for 48 weeks. In group B, patients received adefovir dipivoxil in combination with lamivudine during the first 12 weeks and adefovir dipivoxil only for the following 36 weeks. In group C, patients received adefovir dipivoxil in combination with lamivudine for 48 weeks. In group D, patients received entecavir for 48 weeks.

RESULTS

The rate of rebound of alanine aminotransferase (ALT) was 30.0% (9/30), 10.0% (3/30), 6.7% (2/30), 10.0% (3/30) (P < 0.05) during the first 12 weeks, and one patient with severe hepatitis was found in group A. The positive rate of YMDD mutation was 17.9%, 0, 0, 0 at week 12. There was no significant difference in the level of ALT and the rate of HBeAg seroconversion after 48-week treatment (P > 0.05). At week 48, there was significant difference in the ALT normalization rate and undetectable HBV DNA rate between group C and group A, and also between group D and group A, and the rate of drug resistant genotype was 6.9%, 6.7%, 0, 0. Two patients had rtN236T mutation in group A, and one patient had rtN236T mutation and another one had rtA181V mutation in group B.

CONCLUSION

Adefovir dipivoxil in combination with lamivudine or entecavir are safe and effective therapies for chronic hepatitis B patients with YMDD mutation.

Treatment results in adult-onset recurrent respiratory papillomatosis

PROBLEMS/OBJECTIVES

To assess remission rate, treatment results, and factors for remission in patients with adult-onset recurrent respiratory papillomatosis (AORRP).

METHODOLOGY

In this retrospective study, the clinical and pathological data of 51 patients with AORRP, treated in University Hospitals between 1972 and 2006 were reviewed. The male-female ratio was 7:3. At diagnosis, the median age was 43 years, and the median retrospective Coltrera-Derkay Staging and Severity score was 6 (range, 2-28). Twenty-one patients (41%) received only surgical treatment. Thirty patients (59%) were treated with surgery and adjuvant intralesional cidofovir.

RESULTS

At the time of analysis in December 2006, 69% of the patients were in remission. Of those, 46% had been treated with adjuvant cidofovir. Of the patients who were not in remission, 87% had been treated with adjuvant cidofovir. This difference was statistically significant (p = 0.005). No significant difference was found between the remission group and the non-remission group for the factors age, gender, smoking habits, alcohol habits, GERD, severity and duration of therapy.

CONCLUSIONS

AORRP was curable in most patients after long intensive treatment, with a general remission rate of 69%. Cidofovir was a negative factor for remission (p = 0.005). No other statistically significant factors for remission were found. Although a control group was present, it was not possible to perform a randomized study with comparable groups. A well-designed placebo-controlled, double-blinded, randomized trial to assess the outcomes of adjuvant intralesional cidofovir therapy for RRP would be valuable.

Coadministration of cidofovir and smallpox vaccine reduced vaccination side effects but interfered with vaccine-elicited immune responses and immunity to monkeypox

While the smallpox vaccine, Dryvax or Dryvax-derived ACAM2000, holds potential for public immunization against the spread of smallpox by bioterror, there is serious concern about Dryvax-mediated side effects. Here, we report that a single-dose vaccination regimen comprised of Dryvax and an antiviral agent, cidofovir, could reduce vaccinia viral loads after vaccination and significantly control Dryvax vaccination side effects. However, coadministration of cidofovir and Dryvax also reduced vaccine-elicited immune responses of antibody and T effector cells despite the fact that the reduced priming could be boosted as a recall response after monkeypox virus challenge. Evaluations of four different aspects of vaccine efficacy showed that coadministration of cidofovir and Dryvax compromised the Dryvax-induced immunity against monkeypox, although the covaccinated monkeys exhibited measurable protection against monkeypox compared to that of naïve controls. Thus, the single-dose coadministration of cidofovir and Dryvax effectively controlled vaccination side effects but significantly compromised vaccine-elicited immune responses and vaccine-induced immunity to monkeypox.

[Clinical management of patients with chronic hepatitis B virus infection]

Chronic hepatitis B is still a major public health problem, aggravated by the growing phenomenon of immigration from areas with a high prevalence of infection with this virus. In the last few years, marked progress has been achieved in diagnostic methods, knowledge of the natural history of the disease and in therapeutic options, including liver transplantation, which has improved survival in these patients. These advances have been accompanied by an increase in the complexity of decision making. Six treatments have currently been approved for hepatitis B, including two interferon formulations--standard and pegylated--and four neucleos(t)ide analogs, lamivudine, adefovir, entecavir and telbivudine, as well as two further drugs that are used in patients coinfected with HIV, tenofovir and emtricitabine. However, none of the current treatments is able to eradicate the virus and consequently prolonged treatments are often required with the consequent risk of generating resistance. For this reason, as well as the heterogeneity of the natural history of the disease, there is a lack of consensus on the indications for treatment and the parameters in which treatment should be based, the most suitable drug or drug combination, and the criteria to be used to continue, modify or suspend treatment. Therefore, despite the enormous progress made, numerous questions remain that make the clinical management of these patients a major challenge.

[Hepatitis B in patients with HIV infection]

Chronic hepatitis B virus infection affects approximately 10% of HIV-infected patients. There are an estimated 4 million patients with HIV/HBV coinfection. HIV infection has a deleterious effect on the natural history of chronic hepatitis B and increases the risk of progression to cirrhosis and terminal liver disease. Since the widespread use of highly active antiviral therapy (HAART), liver disease has emerged as one of the main causes of morbidity and mortality in HIV-positive patients. Therefore, all patients with HIV/HBV coinfection should be evaluated for treatment of hepatitis B, independently of the CD4 lymphocyte count. Six drugs are currently authorized for the treatment of chronic hepatitis B: standard interferon-alpha (2a and 2b), pegylated interferon alpha-2a, lamivudine, adefovir, entecavir and telbivudine. Other drugs with activity against HBV, such as tenofovir and emtricitabine, are used for the treatment of HIV infection. In patients not requiring HAART, treatment of hepatitis B should preferably consist of drugs without activity against HIV, such as pegylated interferon or adefovir. In contrast, in patients requiring HAART, a combination of drugs with activity against both viruses should be used, such as lamivudine, emtricitabine and tenofovir, with the aim of achieving maximal viral suppression and avoiding the development of resistance. Patients with HIV/HBV coinfection require periodic clinical and virological monitoring. Patients with cirrhosis should undergo ultrasonography and alphafetoprotein determination every 6 months for the early detection of hepatocellular carcinoma.

Tenofovir disoproxil fumarate versus adefovir dipivoxil for chronic hepatitis B

BACKGROUND

Tenofovir disoproxil fumarate (DF) is a nucleotide analogue and a potent inhibitor of human immunodeficiency virus type 1 reverse transcriptase and hepatitis B virus (HBV) polymerase.

METHODS

In two double-blind, phase 3 studies, we randomly assigned patients with hepatitis B e antigen (HBeAg)-negative or HBeAg-positive chronic HBV infection to receive tenofovir DF or adefovir dipivoxil (ratio, 2:1) once daily for 48 weeks. The primary efficacy end point was a plasma HBV DNA level of less than 400 copies per milliliter (69 IU per milliliter) and histologic improvement (i.e., a reduction in the Knodell necroinflammation score of 2 or more points without worsening fibrosis) at week 48. Secondary end points included viral suppression (i.e., an HBV DNA level of <400 copies per milliliter), histologic improvement, serologic response, normalization of alanine aminotransferase levels, and development of resistance mutations.

RESULTS

At week 48, in both studies, a significantly higher proportion of patients receiving tenofovir DF than of those receiving adefovir dipivoxil had reached the primary end point (P<0.001). Viral suppression occurred in more HBeAg-negative patients receiving tenofovir DF than patients receiving adefovir dipivoxil (93% vs. 63%, P<0.001) and in more HBeAg-positive patients receiving tenofovir DF than patients receiving adefovir dipivoxil (76% vs. 13%, P<0.001). Significantly more HBeAg-positive patients treated with tenofovir DF than those treated with adefovir dipivoxil had normalized alanine aminotransferase levels (68% vs. 54%, P=0.03) and loss of hepatitis B surface antigen (3% vs. 0%, P=0.02). At week 48, amino acid substitutions within HBV DNA polymerase associated with phenotypic resistance to tenofovir DF or other drugs to treat HBV infection had not developed in any of the patients. Tenofovir DF produced a similar HBV DNA response in patients who had previously received lamivudine and in those who had not. The safety profile was similar for the two treatments in both studies.

CONCLUSIONS

Among patients with chronic HBV infection, tenofovir DF at a daily dose of 300 mg had superior antiviral efficacy with a similar safety profile as compared with adefovir dipivoxil at a daily dose of 10 mg through week 48. (ClinicalTrials.gov numbers, NCT00116805 and NCT00117676.)

Changes in sexual risk behavior among participants in a PrEP HIV prevention trial

BACKGROUND

One of the concerns raised regarding the introduction of any new HIV-prevention measure, such as PrEP, is the potential for risk disinhibition or sexual risk compensation. The oral tenofovir HIV prevention trial has been the subject of international discussion in this regard.

METHODS

This article maps the changes in sexual risk behavior among women participating in the oral tenofovir HIV prevention trial in Ghana. Content-driven, thematic analysis was carried out on qualitative data obtained from in-depth interviews with study participants. Growth curve analysis was the primary method used to document trends over time in self-reported sexual behavior collected monthly.

RESULTS

Overall, the study found that sexual risk behavior did not increase during the trial. Number of sexual partners and rate of unprotected sex acts decreased across the 12-month period of study enrollment. Certain subgroups of women, however, exhibited different growth curves. Data indicate that the HIV prevention counseling associated with the trial was effective.

CONCLUSIONS

Counseling during the trial was effective. Different types of counseling and messaging may be needed for different subgroups within a population. These findings also have implications for required sample sizes for future HIV prevention trials where seroconversion is the main outcome.

Low trough levels of tipranavir in a combination antiretroviral therapy of tipranavir/ritonavir and tenofovir require therapeutic drug monitoring

The new non-peptidic protease inhibitor tipranavir is used boosted with ritonavir in a 500/200 mg bid scheme. Multiple drug interactions are described for both drugs because of their different action in CYP450 3A4 and p-glycoprotein. In this retrospective analysis of 22 patients during therapy with tipranavir/ritonavir (TPV) 500 mg/200 mg bid, we found significantly decreased TPV-trough levels in combination with tenofovir (15.32+/-5.22 microg/ml) in comparison to TPV trough levels without tenofovir (20.21+/-14.87 microg/ml). Therapeutic drug monitoring of TPV is recommended.

Core promoter mutant HBV non-responding to adefovir after viral breakthrough on lamivudine: rapid virologic response to tenofovir plus lamivudine in a cirrhotic patient

BACKGROUND

In chronic hepatitis B patients undergoing therapy with LAM or ADV, viral breakthrough is possible due to the emergence of drug resistance. LAM resistant HBV strains are susceptible to ADV, while ADV resistant mutants remain sensitive to LAM.

CASE REPORT

A male patient with HBV-related cirrhosis developed viral breakthrough (HBV DNA>1.8 x 106 IU/ml) after 4 1/2 years of treatment with LAM, and therapy was switched to ADV (10 mg/d). After three months, HBV remained highly replicative without any changes of ALT values, and ADV dose was increased (20 mg/d). Because of unchanged VL sequence analysis was performed three months later, which showed the mutation (rtS219A) and the concomitant mutation (sS210R) and 2 mutations in core promoter region (A1762T), (G1764A). During the sixth month of ADV monotherapy the patient developed liver failure. After administration of TDF plus LAM, HBV DNA became undetectable within 39 days. At day 41, the patient underwent OLT. TDF plus LAM were well tolerated, and the patient maintained undetectable HBV DNA levels, and in addition to HBIG a sustained HBsAg negative status over twenty-eight months post OLT.

CONCLUSION

TDF plus LAM is a safe drug combination in case of viral breakthrough during LAM treatment and subsequent primary non-response to ADV. High VL persisting for >or= 6 months of continuous antiviral treatment may indicate drug resistance. Especially in cirrhotic patients with LAM resistance, "add on" of a nucleotide analogue is the right therapeutic strategy even before viral breakthrough gets apparent.

[Two novel fixed formulations of nucleoside analogues (tenofovir-emtricitabine, and abacavir-lamivudine). Prospective, open study on clinical practice and therapeutic perspectives, in patients naïve and in subjects pre-treated with antiretrovirals]

The introduction of novel, fixed nucleoside-nucleotide reverse transcriptase inhibitor (NRTI) combinations (tenofovir-emtricitabine, and abacavir-lamivudine), expanded the spectrum of available formulations and increased patient's adherence. A prospective survey of the open-label use of these two fixed combinations was performed in 158 patients belonging to our single-centre cohort of over 1,000 HIV-infected subjects enrolled in the last 18 months, and followed for at least 12 months. During the last 18 months, 95 consecutive, evaluable patients (60.1%) received for the first time tenofovir-emtricitabine, or abacavir-lamivudine (63 patients, 39.9%), and were followed for at least 12 months. A major role seems to be played by tenofovir-emtricitabine in first-line treatments (preferably among "compact" regimens based on efavirenz), while the proportionally increased abacavir-lamivudine prescription to pre-treated patients is mostly attributable to the different genetic barrier of abacavir (often associated with boosted protease inhibitors, in this last patient group). The present availability to two more fixed NRTI combinations favored by their single pill, once-daily administration encourages randomized, controlled "head to head" studies in both first-line and experienced patients, in order to better exploit and target their therapeutic potential.

Multidrug resistance-associated protein 2 (MRP2) affects hepatobiliary elimination but not the intestinal disposition of tenofovir disoproxil fumarate and its metabolites

The role of multidrug resistance-associated protein 2 (MRP2) on the intestinal disposition and hepatobiliary elimination of tenofovir disoproxil fumarate (DF) and its metabolites [tenofovir (mono)ester and tenofovir] was studied in the Caco-2 system, Ussing chambers and rat in-situ efflux experiments. In the Caco-2 model and Ussing chambers, no statistically significant differences in transport could be observed when the MRP inhibitor probenecid was included. In Ussing chambers, transport was also similar when using intestinal tissue from MRP2-deficient rats. After intravenous administration of tenofovir DF, the excretion of tenofovir [(mono)ester] in bile was significantly decreased in MRP2-deficient rats and in rats treated with probenecid. The area under the blood concentration-time curve was increased in MRP2-deficient rats [1.0+/-0.1 and 0.36+/-0.03 microM.min-1 for tenofovir and tenofovir (mono)ester, respectively] and rats treated with probenecid (1.42+/-0.04 and 0.36+/-0.02 microM.min-1) compared with control rats (0.64+/-0.05 and 0.15+/-0.06 microM.min-1). The appearance of tenofovir [(mono)ester] in intestinal perfusate was similar in control rats upon co-administering probenecid or when using MRP2-deficient rats. In conclusion, MRP2 appeared to have no modulatory effect on the intestinal disposition of tenofovir and tenofovir (mono)ester. However, inhibition (probenecid) or the total absence of MRP2 (MRP2-deficient rats) significantly reduced hepatobiliary elimination, which was accompanied by increased systemic exposure.

Chronic administration of tenofovir to rhesus macaques from infancy through adulthood and pregnancy: summary of pharmacokinetics and biological and virological effects

The reverse transcriptase (RT) inhibitor tenofovir (TFV) is highly effective in the simian immunodeficiency virus (SIV) macaque model of human immunodeficiency virus infection. The current report describes extended safety and efficacy data on 32 animals that received prolonged (>or=1- to 13-year) daily subcutaneous TFV regimens. The likelihood of renal toxicity (proximal renal tubular dysfunction [PRTD]) correlated with plasma drug concentrations, which depended on the dosage regimen and age-related changes in drug clearance. Below a threshold area under the concentration-time curve for TFV in plasma of approximately 10 microg x h/ml, an exposure severalfold higher than that observed in humans treated orally with 300 mg TFV disoproxil fumarate (TDF), prolonged TFV administration was not associated with PRTD based on urinalysis, serum chemistry analyses, bone mineral density, and clinical observations. At low-dose maintenance regimens, plasma TFV concentrations and intracellular TFV diphosphate concentrations were similar to or slightly higher than those observed in TDF-treated humans. No new toxicities were identified. The available evidence does not suggest teratogenic effects of prolonged low-dose TFV treatment; by the age of 10 years, one macaque, on TFV treatment since birth, had produced three offspring that were healthy by all criteria up to the age of 5 years. Despite the presence of viral variants with a lysine-to-arginine substitution at codon 65 (K65R) of RT in all 28 SIV-infected animals, 6 animals suppressed viremia to undetectable levels for as long as 12 years of TFV monotherapy. In conclusion, these findings illustrate the safety and sustained benefits of prolonged TFV-containing regimens throughout development from infancy to adulthood, including pregnancy.

Lack of a significant drug interaction between raltegravir and tenofovir

Raltegravir is a novel human immunodeficiency virus type 1 (HIV-1) integrase inhibitor with potent in vitro activity (95% inhibitory concentration of 31 nM in 50% human serum). This article reports the results of an open-label, sequential, three-period study of healthy subjects. Period 1 involved raltegravir at 400 mg twice daily for 4 days, period 2 involved tenofovir disoproxil fumarate (TDF) at 300 mg once daily for 7 days, and period 3 involved raltegravir at 400 mg twice daily plus TDF at 300 mg once daily for 4 days. Pharmacokinetic profiles were also determined in HIV-1-infected patients dosed with raltegravir monotherapy versus raltegravir in combination with TDF and lamivudine. There was no clinically significant effect of TDF on raltegravir. The raltegravir area under the concentration time curve from 0 to 12 h (AUC(0-12)) and peak plasma drug concentration (C(max)) were modestly increased in healthy subjects (geometric mean ratios [GMRs], 1.49 and 1.64, respectively). There was no substantial effect of TDF on raltegravir concentration at 12 h postdose (C(12)) in healthy subjects (GMR [TDF plus raltegravir-raltegravir alone], 1.03; 90% confidence interval [CI], 0.73 to 1.45), while a modest increase (GMR, 1.42; 90% CI, 0.89 to 2.28) was seen in HIV-1-infected patients. Raltegravir had no substantial effect on tenofovir pharmacokinetics: C(24), AUC, and C(max) GMRs were 0.87, 0.90, and 0.77, respectively. Coadministration of raltegravir and TDF does not change the pharmacokinetics of either drug to a clinically meaningful degree. Raltegravir and TDF may be coadministered without dose adjustments.

Pharmacotherapy of hepatitis B infection: a brief review

Chronic infection with hepatitis B virus can lead to liver disease, cirrhosis, and hepatocellular carcinoma. Treatment options include interferons and antiviral drugs. The interferons have immunomodulatory, antiproliferative, and antiviral effects. Nucleoside analogs, such as entecavir, lamivudine and telbivudine, and neucleotide analogs, such as adefovir and tenofovir, exhibit antiviral effects by inhibiting viral replication. Treatment is directed at suppressing viral replication and halting the progression of disease.

Effectiveness and safety of generic fixed-dose combination of tenofovir/emtricitabine/efavirenz in HIV-1-infected patients in Western India

OBJECTIVE

To assess effectiveness and safety of a generic fixed-dose combination of tenofovir (TDF)/emtricitabine (FTC)/efavirenz (EFV) among HIV-1-infected patients in Western India.

METHODS

Antiretroviral (ARV)-naive and experienced (thymidine analog nucleoside reverse transcriptase inhibitor [tNRTI] replaced by TDF) patients were started on a regimen of 1 TDF/FTC/EFV pill once a day. They were followed clinically on a periodic basis, and viral loads and CD4 counts were measured at 6 and 12 months. Creatinine clearance was calculated at baseline and at 6 months and/or as clinically indicated. Effectiveness was defined as not having to discontinue the regimen due to failure or toxicity.

RESULTS

One hundred forty-one patients who started TDF/FTC/EFV before 1 June 2007 were eligible. Of these, 130 (92.2%) and 44 (31.2%) had 6- and 12-months follow-up, respectively. Thirty-five percent of the patients were ARV-naive. Eleven patients discontinued treatment (4 for virologic failure, 1 for grade 3-4 central nervous system disturbances, 4 for grade 3-4 renal toxicity, and 2 for cost). Ninety-six percent of patients were virologically suppressed at 6 months. Frequency of TDF-associated grade 3-4 renal toxicity was 2.8%; however, 3 of these patients had comorbid conditions associated with renal dysfunction.

CONCLUSION

A fixed-dose combination of generic TDF/FTC/EFV is effective in ARV-naive and experienced patients. Although frequency of severe renal toxicity was higher than has been reported in the literature, it was safe in patients with no comorbid renal conditions.

Prevention of SIV rectal transmission and priming of T cell responses in macaques after local pre-exposure application of tenofovir gel

BACKGROUND

The rectum is particularly vulnerable to HIV transmission having only a single protective layer of columnar epithelium overlying tissue rich in activated lymphoid cells; thus, unprotected anal intercourse in both women and men carries a higher risk of infection than other sexual routes. In the absence of effective prophylactic vaccines, increasing attention is being given to the use of microbicides and preventative antiretroviral (ARV) drugs. To prevent mucosal transmission of HIV, a microbicide/ARV should ideally act locally at and near the virus portal of entry. As part of an integrated rectal microbicide development programme, we have evaluated rectal application of the nucleotide reverse transcriptase (RT) inhibitor tenofovir (PMPA, 9-[(R)-2-(phosphonomethoxy) propyl] adenine monohydrate), a drug licensed for therapeutic use, for protective efficacy against rectal challenge with simian immunodeficiency virus (SIV) in a well-established and standardised macaque model.

METHODS AND FINDINGS

A total of 20 purpose-bred Indian rhesus macaques were used to evaluate the protective efficacy of topical tenofovir. Nine animals received 1% tenofovir gel per rectum up to 2 h prior to virus challenge, four macaques received placebo gel, and four macaques remained untreated. In addition, three macaques were given tenofovir gel 2 h after virus challenge. Following intrarectal instillation of 20 median rectal infectious doses (MID50) of a noncloned, virulent stock of SIVmac251/32H, all animals were analysed for virus infection, by virus isolation from peripheral blood mononuclear cells (PBMC), quantitative proviral DNA load in PBMC, plasma viral RNA (vRNA) load by sensitive quantitative competitive (qc) RT-PCR, and presence of SIV-specific serum antibodies by ELISA. We report here a significant protective effect (p = 0.003; Fisher exact probability test) wherein eight of nine macaques given tenofovir per rectum up to 2 h prior to virus challenge were protected from infection (n = 6) or had modified virus outcomes (n = 2), while all untreated macaques and three of four macaques given placebo gel were infected, as were two of three animals receiving tenofovir gel after challenge. Moreover, analysis of lymphoid tissues post mortem failed to reveal sequestration of SIV in the protected animals. We found a strong positive association between the concentration of tenofovir in the plasma 15 min after rectal application of gel and the degree of protection in the six animals challenged with virus at this time point. Moreover, colorectal explants from non-SIV challenged tenofovir-treated macaques were resistant to infection ex vivo, whereas no inhibition was seen in explants from the small intestine. Tissue-specific inhibition of infection was associated with the intracellular detection of tenofovir. Intriguingly, in the absence of seroconversion, Gag-specific gamma interferon (IFN-gamma)-secreting T cells were detected in the blood of four of seven protected animals tested, with frequencies ranging from 144 spot forming cells (SFC)/10(6) PBMC to 261 spot forming cells (SFC)/10(6) PBMC.

CONCLUSIONS

These results indicate that colorectal pretreatment with ARV drugs, such as tenofovir, has potential as a clinically relevant strategy for the prevention of HIV transmission. We conclude that plasma tenofovir concentration measured 15 min after rectal administration may serve as a surrogate indicator of protective efficacy. This may prove to be useful in the design of clinical studies. Furthermore, in vitro intestinal explants served as a model for drug distribution in vivo and susceptibility to virus infection. The finding of T cell priming following exposure to virus in the absence of overt infection is provocative. Further studies would reveal if a combined modality microbicide and vaccination strategy is feasible by determining the full extent of local immune responses induced and their protective potential.

Solid lipid nanoparticles loading adefovir dipivoxil for antiviral therapy

Herein, solid lipid nanoparticles (SLN) were proposed as a new drug delivery system for adefovir dipivoxil (ADV). The octadecylamine-fluorescein isothiocynate (ODA-FITC) was synthesized and used as a fluorescence maker to be incorporated into SLN to investigate the time-dependent cellular uptake of SLN by HepG2.2.15. The SLN of monostearin with ODA-FITC or ADV were prepared by solvent diffusion method in an aqueous system. About 15 wt% drug entrapment efficiency (EE) and 3 wt% drug loading (DL) could be reached in SLN loading ADV. Comparing with free ADV, the inhibitory effects of ADV loaded in SLN on hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA levels in vitro were significantly enhanced.