[Non-cirrhotic portal hypertension due to didanosina. A rare case]

Liver involvement is usually seen in patients infected with the human immunodeficiency virus (HIV), especially in patients coinfected with hepatitis B or C, in alcohol abuse, etc. However, there is a group of patients who develop liver involvement and portal hypertension of unspecified cause. Non-cirrhotic portal hypertension (NCPH) is a liver disorder recently described, but potentially serious. It has been reported in HIV-infected patients with highly active antiretroviral therapy (HAART), specifically didanosine (DDI). The pathophysiology involves the infectious agent (HIV) and its treatment (HAART), since both generate a pre-hepatic portal venulopathy. Similarly, HIV infection produces a prothrombotic state by protein S deficiency leading to the obliteration of small hepatic venules. It has been postulated that DDI as a cofactor in the pathogenesis of NCPH. All this leads that many of the liver biopsies show nodular regenerative hyperplasia. We present the case of a HIV-infected patient who was treated with a longstanding DDI. She developed upper gastrointestinal bleeding (UGB) and ascites due to NCPH, whose diagnosis was confirmed by biopsy. However, there is no similar study in our country.

Didanosine Therapy in Patients Intolerant of or Failing Zidovudine Therapy

OBJECTIVE:

To examine the effect of didanosine (2′,3′-dideoxyinosine, ddI) on surrogate markers of HIV infection (CD4+ lymphocyte count, p24 antigen) and to evaluate the incidence of adverse effects from ddI.

DESIGN:

This study was performed as a retrospective chart review of patients who were enrolled in Bristol-Myers Squibb's expanded-access program for ddI.

SETTING:

Patient records were obtained from primary care physicians' offices.

PATIENTS:

Twenty-five HIV-infected patients diagnosed with AIDS or AIDS-related complex (ARC) who were intolerant of zidovudine (ZDV) therapy or deteriorating clinically despite ZDV therapy and were eligible for inclusion in the ddI expanded-access program.

INTERVENTION:

ddI was administered orally in a citrate-phosphate buffer every 12 hours. Patients were followed by their private physician on a monthly basis.

MAIN OUTCOME MEASURES:

Laboratory analysis at each month included CD4+ lymphocyte count, hemoglobin, hematocrit, serum amylase, uric acid, serum triglycerides, and p24 antigen. Mean CD4+ cell count, serum amylase, hemoglobin, and uric acid at each month during ddI therapy were compared with baseline concentrations for nine months.

RESULTS:

Patients had received prior ZDV therapy for an average of 15.5 months before starting ddI. Mean CD4+ cell counts increased from 53.9/mm3 at baseline to 72.4/mm3 after 4 months of therapy (p=0.04) but returned to concentrations comparable with those at baseline after 5 months. One case of documented pancreatitis, two cases of suspected pancreatitis, and nine cases of peripheral neuropathy occurred during ddI therapy. The estimated mean cumulative dose for the development of neuropathy was 1.16 g/kg, which is lower than previously reported.

CONCLUSIONS:

Patients who have received prolonged therapy with ZDV or who have low initial CD4+ counts may not have sustained increases in CD4+ counts from ddI therapy. Also, development of peripheral neuropathy may occur at lower cumulative doses in these patient populations.

Didanosine

OBJECTIVE:

To review the chemistry, intracellular metabolism, pharmacokinetics, and clinical experience with didanosine (2',3'-dideoxyinosine [ddI]).

DATA SOURCES:

English-language articles and conference proceedings (indexing terms were didanosine, 2′,3′-dideoxyinosine, and ddI).

STUDY SELECTION:

Available Phase I studies and abstracts determined to have clinical significance were included.

DATA EXTRACTION:

Clinical experience with ddI is limited to uncontrolled Phase I studies and a large “expanded-access” program. The primary outcome parameters used to evaluate ddI were the HIV surrogate markers: CD4+ lymphocytes and p24 antigen. Thus, the clinical data reviewed here must be evaluated critically and be considered preliminary until the results of studies comparing ddI with zidovudine (ZDV) and combination studies are available.

DATA SYNTHESIS:

Didanosine has been approved for the treatment of HIV infection in patients who are unable to tolerate ZDV because of adverse effects (e.g., anemia and neutropenia) or who experience clinical or immunologic deterioration while receiving ZDV. Compared with ZDV, ddI has a long intracellular half-life and negligible bone-marrow toxicity. It also has in vitro activity against ZDV-resistant strains of HIV. Phase I studies indicate that ddI has a beneficial effect on the CD4+ cell counts and HIV p24 antigen concentrations. As a result of the acid-labile nature of ddI, oral formulations are buffered or must be mixed with antacid to neutralize gastric pH. Bioavailability then averages 20–40 percent, depending on the dose and formulation given. The plasma half-life, total body clearance, and volume of distribution of ddI are one to two hours, 0.7–1 L/kg/h, and 0.8–1 L/kg, respectively. Painful peripheral neuropathy and pancreatitis (dose-limiting toxicities of ddI) occurred in 34 and 9 percent of patients in Phase I studies, respectively.

CONCLUSIONS:

Didanosine has demonstrated preliminary efficacy in the treatment of late-stage HIV infection; however, its effect on patient survival, its efficacy relative to ZDV, and its utility in combination with other agents are still under evaluation.

Risk Factors for Hyperlactataemia in HIV-Infected Patients, Aquitaine Cohort, 1999–2003

The objectives of our study were to describe the characteristics of a subset of patients who had been prescribed serum lactate in clinical practice within a large cohort of HIV-infected patients and to determine the factors associated with hyperlactataemia. Hyperlactataemia (⩾T2 mmol/l) was found in 219 [29% (95% confidence interval: 25.3–31.7)] of the 768 HIV-infected participants. In multivariate analysis (logistical regression), an increased risk of hyperlactataemia was associated with increasing age, CD4 count <500/mm3, triglycerides >2.2 mmol/L, lipoatrophy and stavudine use. In a second model coding for the NRTI-based drug combinations, only those including stavudine were associated with an increased risk of hyperlactataemia. In a third model including exposure duration to NRTIs, we estimated a 20% increased risk of hyperlactataemia per year of exposure to didanosine or stavudine. The risk of hyperlactataemia could increase over time in patients treated with these drugs and is also closely associated with increased age, decreased CD4 count, lipodystrophy and increased plasma triglycerides. It could be proposed that patients having one or more of these risk factors undergo regular monitoring of plasma lactate and renal function to prevent lactic acidosis.

A farewell to didanosine: harm reduction and cost savings by eliminating use of didanosine

Didanosine (ddI) is a nucleoside reverse transcriptase inhibitor associated with adverse events and public health concerns which have diminished its place in HIV clinical practice, particularly in resource-rich settings. While international guidelines do not contain ddI-containing regimens in preferred first- or second-line antiretroviral therapy (ART), there is no guidance for management of patients currently on ddI. In 2012 at least 20 countries purchased a total of $1-2 million of ddI. Drug purchase data in that year show 3.2-10.3 times higher costs for ddI compared to lamivudine (3TC). Given issues of multiple toxicities, monitoring, drug interactions, inconvenience, and virologic efficacy, as well as cost and formulary concerns, national (including resource-limited setting) ART programmes should consider complete phase-out of ddI.

Simplicity and Efficacy of a Once-Daily Antiretroviral Regimen with Didanosine, Lamivudine, and Efavirenz in Naïve Patients: The VESD Study

PURPOSE

Our aim was to analyze the efficacy and safety of didanosine-lamivudine-efavirenz in a cohort of HIV patients starting antiretroviral therapy between January and September 2003.

METHOD

We undertook a prospective, open-label, observational, multicenter study.

RESULTS

163 patients were enrolled. Over a 48-week period, plasma HIV RNA levels declined sharply, with a median decrease at the end of the observation time of >4.62 log copies/mL. The proportion of patients achieving a plasma HIV RNA level below 50 copies/mL was 62.9% (intention-to-treat analysis) at the end of the study period. The mean CD4 cell count increased steadily over time by 199 cells/microL. Antiviral efficacy was similar in patients with a baseline HIV RNA level above or below 100,000 copies/mL. Overall, 57 (34.1%) patients interrupted therapy; 9 due to lack of treatment response, 18 due to adverse side-effects, and 30 patients lost to follow-up or who withdrew their consent. Adherence was very high (90%-95%) and quality of life was good or very good in 69%.

CONCLUSION

The once-daily combination of didanosine-lamivudine-efavirenz resulted in sustained viral suppression and was well-accepted by patients under real-life conditions, even immunosuppressed patients and those with a high viral load. Associated adverse events and virological failures were few.

Comparison of Two Once-Daily Regimens with a Regimen Consisting of Nelfinavir, Didanosine, and Stavudine in Antiretroviral Therapy-Naïve Adults: 48-Week Results from the Antiretroviral Regimen Evaluation Study (ARES)

BACKGROUND

To improve the dosing frequency and pill burden of antiretroviral therapy, we compared two once-daily dosed regimens to a twice-daily dosed regimen.

METHOD

HIV-1-infected, antiretroviral drug-naïve adults were randomized to either twice-daily nelfinavir and stavudine and once-daily didanosine (regimen A) or simplified once-daily dosed antiretroviral regimens consisting of nevirapine, didanosine, and lamivudine (regimen B) or saquinavir, ritonavir, didanosine, and lamivudine (regimen C).

RESULTS

At 48 weeks of therapy, the proportion of patients with a blood plasma HIV-1 RNA concentration (pVL) <50 copies/mL by intention-to treat analysis was 42.3%, 50.0%, and 56.5% for regimens A (n = 26), B (n = 22), and C (n = 23), respectively. The time to a pVL <50 copies/mL for the first time was significantly shorter in regimen C, and there was significantly more progression to CDC events in regimen B. These differences are possibly due to differences in baseline characteristics. Adverse events were lowest for regimen C; more signs associated with mitochondrial toxicity occurred in regimen A. Increase in CD4 count was comparable between arms.

CONCLUSION

No statistically significant difference in efficacy was found between the two investigated once-daily dosed treatment regimens (B and C) and the reference (A). Regimen C possibly had a better virological response and less toxicity than regimens A and B.

A woman with didanosine retinopathy and non-cirrhotic portal hypertension

We present a case of structural and functional changes compatible with didanosine retinopathy in a patient who also developed non-cirrhotic portal hypertension.

Drug-Drug and Drug-Food Interactions Between Tenofovir Disoproxil Fumarate and Didanosine

The drug-drug and drug-food interactions between tenofovir DF and didanosine EC were evaluated in 2 pharmacokinetic studies in healthy adult subjects. When 400 mg was dosed with tenofovir DF, mean didanosine AUC was increased by 44% to 60% following fasted or fed administration. Staggered coadministration (2 hour, fasted) of a reduced didanosine dose of 250 mg resulted in equivalent didanosine exposure, while simultaneous administration with tenofovir DF in the fasted and fed state resulted in didanosine AUCs similar to that of the reference treatment of 400 mg alone in the fasted state. These data indicate that a dose reduction of didanosine is warranted when it is used with tenofovir DF. The drug-drug-food interaction of didanosine may offer more flexible dosing of didanosine EC when it is used with tenofovir DF. Patients receiving tenofovir DF and didanosine together should be carefully monitored for safety and efficacy.

An unusual cause of oesophageal variceal bleeding in a Chinese human immunodeficiency virus-infected patient

Non-cirrhotic portal hypertension is an unusual but potentially serious liver disorder in human immunodeficiency virus-infected patients with prolonged exposure to didanosine. Due to its rarity, the diagnosis is often delayed. It is postulated that didanosine contributes to obliterative portal venopathy and causes portal hypertension. Affected patients may present with abnormal liver function or signs of portal hypertension, while the diagnosis usually depends on liver biopsy. We report a case of non-cirrhotic portal hypertension in a human immunodeficiency virus-infected patient. The reported histological features include nodular regenerative hyperplasia and hepatoportal sclerosis. Early recognition is important as timely management of severe portal hypertension may prevent potentially fatal gastro-intestinal bleeding.

The role of nucleoside reverse transcriptase inhibitors usage in the incidence of hyperlactatemia and lactic acidosis in HIV/AIDS patients

Hyperlactatemia and lactic acidosis (LA) are among the most dangerous and life-threatening side effect that occurs during therapy with some nucleoside reverse transcriptase inhibitors (NRTIs), mainly didanosine (ddI) and stavudine (d4T), also known as d-drugs. Therefore, we performed a prospective, follow-up study and aimed to examine the incidence rates (IR) and rate ratios (RR) of hyperlactatemia and LA for each NRTI. Three hundred and ninety-six HIV-patients were included in final analysis comprising 783.8 person-years of follow-up. Between 1st January 2000 and 1st January 2008, 19 cases of hyperlactatemia and 15 cases of LA were recorded. Between regimens with the significant impact for developing hyperlactatemia and LA the lowest IR was for didanosine (IR=2.87 per 100 person-years, 95%CI=0.45-9.25 and IR=4.31 per 100 person-years, 95%CI=1.07-13.91, respectively), and the highest for didanosine+stavudine (IR=10.17 per 100 person-years, 95%CI=1.02-19.76 and IR=7.39 per 100 person-years, 95%CI=1.02-13.05, respectively). Compared to didanosine alone the RR of hyperlactatemia was 2.67 (95%CI=1.11-12.52) for stavudine, and 4.06 (95%CI=1.31-15.48) for didanosine+stavudine. The RR of LA was 3.12 (95%CI=1.13-10.65) for stavudine, and 5.13 (95%CI=1.54-13.37) for didanosine+stavudine in comparison with didanosine alone. Other risk factors for AP were CD4 cell count less than 200 cells/mm³ and female sex. Our results suggest that the use of stavudine alone or in combination with didanosine should not be used as first-line therapy, especially in patients with CD4 cell count less than 200 cells/mm³ and females if other treatment options are available.

Noncirrhotic portal hypertension associated with didanosine: a case report and literature review

Noncirrhotic portal hypertension (NCPH) has recently been reported as a liver complication in human immunodeficiency virus (HIV)-infected patients and has been found to be associated with exposure to didanosine. Here, we describe the case of an HIV-infected patient with portal hypertension who initially presented with massive ascites and portal vein thrombosis. The patient's HIV-1 infection was well-controlled with highly active antiretroviral therapy (lamivudine/didanosine plus nevirapine) for 3 years since its diagnosis in 2007. He had no history of alcoholism, drug abuse, or liver diseases. An extensive work-up for other possible causes of liver disease was performed, but the results were inconclusive. In addition to reporting this case, we have reviewed the literature on didanosine-related NCPH and analyzed the findings of 61 similar previously reported cases.

[Regenerative nodular hyperplasia in HIV]

Nodular regenerative hyperplasia of the liver is a rare condition. We describe here the case of a patient with HIV who presented with a clinical syndrome of portal hypertension. After multiple evaluations the diagnosis was recognized by the histology. The findings were attributed to the prolonged use of didanosine.

A randomized factorial trial comparing 4 treatment regimens in treatment-naive HIV-infected persons with AIDS and/or a CD4 cell count <200 cells/μL in South Africa

BACKGROUND

Few randomized trials comparing antiretroviral therapy (ART) regimens have been conducted in resource-limited settings.

METHODS

In the Republic of South Africa, antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals >14 years old with a CD4 cell count <200 cells/μL or a prior AIDS diagnosis were randomized to receive efavirenz (EFV) or lopinavir/ritonavir (LPV/r) with either zidovudine (ZDV) plus didanosine (ddI) or stavudine (d4T) plus lamivudine (3TC) in an open-label, 2-by-2 factorial study and followed up for the primary outcome of AIDS or death and prespecified secondary outcomes, including CD4 cell count and viral load changes, treatment discontinuation, and grade 4 events.

RESULTS

In total, 1771 persons were randomized and followed up for a median of 24.7 months. AIDS or death occurred in (1) 163 participants assigned EFV and 157 assigned LPV/r (hazard ratio [HR], 1.04 [95% confidence interval {CI}, 0.84-1.30]) and in (2) 170 participants assigned ZDV+ddI and 150 assigned d4T+3TC (HR, 1.15 [95% CI, 0.93-1.44]). HIV RNA levels were lower (P < .001) and CD4 cell counts were greater (P < .01) over follow-up for d4T+3TC versus ZDV+ddI. Rates of potentially life-threatening adverse events and overall treatment discontinuation were similar for d4T+3TC and ZDV+ddI; however, more participants discontinued d4T because of toxicity (12.6%) than other treatments (<5%).

CONCLUSION

EFV and LPV/r are effective components of first-line ART. The poorer viral and immune responses with ZDV+ddI and the greater toxicity-associated discontinuation rate with d4T+3TC suggest that these treatments be used cautiously as initial therapy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00342355.

Efficacy and safety of 1-month postpartum zidovudine-didanosine to prevent HIV-resistance mutations after intrapartum single-dose nevirapine

BACKGROUND

Intrapartum single-dose nevirapine plus third trimester maternal and infant zidovudine are essential components of programs to prevent mother-to-child transmission of human immunodeficiency virus (HIV) in resource-limited settings. The persistence of nevirapine in the plasma for 3 weeks postpartum risks selection of resistance mutations to nonnucleoside reverse-transcriptase inhibitors (NNRTIs). We hypothesized that a 1-month zidovudine-didanosine course initiated at the same time as single-dose nevirapine (sdNVP) would prevent the selection of nevirapine-resistance mutations.

METHODS

HIV-infected pregnant women in the PHPT-4 cohort with CD4 cell counts >250 cells/mm3 received antepartum zidovudine from the third trimester until delivery, sdNVP during labor, and a 1-month zidovudine-didanosine course after delivery. These women were matched on the basis of baseline HIV load, CD4 cell count, and duration of antepartum zidovudine to women who received sdNVP in the PHPT-2 trial (control subjects). Consensus sequencing and the more sensitive oligonucleotide ligation assay were performed on samples obtained on postpartum days 7-10, 37-45, and 120 (if the HIV load was >500 copies/mL) to detect K103N/Y181C/G190A mutations.

RESULTS

The 222 PHPT-4 subjects did not differ from matched control subjects in baseline characteristics except for age. The combined group median CD4 cell count was 421 cells/mm3 (interquartile range [IQR], 322-549 cells/mm3), the median HIV load was 3.45 log10 copies/mL (IQR, 2.79-4.00 log10 copies/mL), and the median duration of zidovudine prophylaxis was 10.4 weeks (IQR, 9.1-11.4 weeks). Using consensus sequencing, major NNRTI resistance mutations were detected after delivery in 0% of PHPT-4 subjects and 10.4% of PHPT-2 controls. The oligonucleotide ligation assay detected resistance in 1.8% of PHPT-4 subjects and 18.9% of controls. Major NNRTI resistance mutations were detected by either method in 1.8% of PHPT-4 subjects and 20.7% of controls (P < .001).

CONCLUSIONS

A 1-month postpartum course of zidovudine plus didanosine prevented the selection of the vast majority of NNRTI resistance mutations.

[Therapeutic effect and safety evaluation on 6-year highly active antiretroviral therapy for Chinese HIV-1 infected patients]

OBJECTIVE

To evaluate the long-term efficacy and safety of nevirapine (NVP)-based regimens for HIV-infected Chinese patients in routine clinical practice.

METHODS

From October 2002 to May 2004, 57 HIV-1-infected patients commenced highly active antiretroviral therapy (HAART), and were followed to December 2008. They originally received 2 nucleoside reverse transcriptase inhibitors (NRTIs) and nevirapine. HIV RNA levels, T lymphocyte subsets and safety were assessed. Blood routine test and main laboratory parameter changes were traced. If apparent side effects or virological failure appeared we would, if necessary, terminate the therapy or change the regimen.

RESULTS

Of the 57 subjects, 34 were followed-up for more than 4 years. After 5-6 years, 63.3% of the subjects (19/30) had HIV RNA levels<50 copies/microL, and the median increase in CD4(+) cell count from the baseline was 329 cells/microL. The mean decrease in CD8(+) cell count was 128 cells/microL. At the same time, the CD4(+) CD45RA+CD62L cell count and CD4(+)CD45RO(+) cell gradually increased, and the counts of CD8(+)CD38(+) cell declined gradually. These changes are apparent 2 years after HAART. The increase rate slowed down after 2 years. But they did not recover completely as well as healthy people at year 6. About 56% (32/57) of HIV-infected patients developed various drug-related side effects. The most common was gastrointestinal side effect, followed nervous disorder, baldness, and rashes, mostly happened in 6 months. Gamma-GT increased occurred in 29.8% of patients (17/57), and serum cholesterol and triglyceride elevated in 26.3% of the patients (15/57). Six patients developed lipodystrophy, mainly in female patients, and 25 patients showed abnormal blood picture and liver function, renal function changes and amylase elevation. Grade 3-4 adverse events occurred in 3 cases (2 peripheral neuropathy, and 1 suspected lactic acidosis). One subject experienced grade 3 rashes.

CONCLUSION

Antiretroviral therapy with NVP-based regimens is safe and effective by suppressing HIV viremia and producing continued CD4 cell increases in subjects with HIV or AIDS for 6 years.

Proximal tubular dysfunction associated with tenofovir and didanosine causing Fanconi syndrome and diabetes insipidus: a report of 3 cases

We report 3 cases of patients with HIV/AIDS in whom Fanconi syndrome and nephrogenic diabetes insipidus developed secondary to use of an antiretroviral regimen containing tenofovir disoproxil fumarate and didanosine. These patients presented with a history of polydipsia, polyuria, weight loss, anorexia, and wasting. Interestingly, 1 patient was not taking protease inhibitors. This response is a well-documented yet uncommon complication of tenofovir use in the HIV population. We recommend continued monitoring for renal toxicity when using NRTI combination of tenofovir and didanosine.

Use of nucleoside reverse transcriptase inhibitors and risk of myocardial infarction in HIV-infected patients enrolled in the D:A:D study: a multi-cohort collaboration

BACKGROUND

Whether nucleoside reverse transcriptase inhibitors increase the risk of myocardial infarction in HIV-infected individuals is unclear. Our aim was to explore whether exposure to such drugs was associated with an excess risk of myocardial infarction in a large, prospective observational cohort of HIV-infected patients.

METHODS

We used Poisson regression models to quantify the relation between cumulative, recent (currently or within the preceding 6 months), and past use of zidovudine, didanosine, stavudine, lamivudine, and abacavir and development of myocardial infarction in 33 347 patients enrolled in the D:A:D study. We adjusted for cardiovascular risk factors that are unlikely to be affected by antiretroviral therapy, cohort, calendar year, and use of other antiretrovirals.

FINDINGS

Over 157,912 person-years, 517 patients had a myocardial infarction. We found no associations between the rate of myocardial infarction and cumulative or recent use of zidovudine, stavudine, or lamivudine. By contrast, recent-but not cumulative-use of abacavir or didanosine was associated with an increased rate of myocardial infarction (compared with those with no recent use of the drugs, relative rate 1.90, 95% CI 1.47-2.45 [p=0.0001] with abacavir and 1.49, 1.14-1.95 [p=0.003] with didanosine); rates were not significantly increased in those who stopped these drugs more than 6 months previously compared with those who had never received these drugs. After adjustment for predicted 10-year risk of coronary heart disease, recent use of both didanosine and abacavir remained associated with increased rates of myocardial infarction (1.49, 1.14-1.95 [p=0.004] with didanosine; 1.89, 1.47-2.45 [p=0.0001] with abacavir).

INTERPRETATION

There exists an increased risk of myocardial infarction in patients exposed to abacavir and didanosine within the preceding 6 months. The excess risk does not seem to be explained by underlying established cardiovascular risk factors and was not present beyond 6 months after drug cessation.

[Evaluation of antiretroviral therapy in HIV-infected adults in the Department of Haematology, University Hospital of Brazzavllle, Congo]

A retrospective study was conducted during 32 months; from 1 May 2003 to 30 December 2005 in haematology department. The objective of the study was to assess the effectiveness of the anti retroviral therapy 157 patients receiving antiretroviral treatment for at least a twelve month-period and presenting AIDS symptoms based on revised CDC criteria were included. The average number of initial T4 lymphocytes is 133/mm3 (extremes 1 and 385) and the initial plasmatic average viral load, quantified in 96 patients is 214,000 copies (extreme 30,000 et 999,000) The initial antiretroviral combinations were as follows: ZDV or D4T + LMV + NVP (59.2%); ZDV or D4T + LMV + EFV (28.7%), ZDV or D4T + LMV + IDNV (8.9%); ZDV or D4T + DDI + NVP (3.2%). The results of the study are: observance rate during the first 12 months (84%), antiretroviral therapy taken irregularly (10.8%), early submission of therapy (5.2%), weight gain after 24 months: +18 kgs, clinical response globally positive. The immune response is characterised by an average increase of 353/mm3 of CD4 after 24 months. Among 96 patients tested, the plasmatic viral load was undetectable in 71% of cases after a 12 month-follow up. Mild adverse drug effects have been noticed, represented by cutaneous and nervous toxicity anaemia and digestive disorders due to indinavir These therapeutic results confirm the importance of the antiretroviral therapy in the improvement of the quality of life of HIV/AIDS patients but a concern remains on the possible drug resistance still not documented.

The risk of developing peripheral neuropathy induced by nucleoside reverse transcriptase inhibitors decreases over time: evidence from the Delta trial

BACKGROUND

Peripheral neuropathy (PN) in HIV-infected individuals is thought be due to a toxic effect on mitochondria induced by some nucleoside reverse transcriptase inhibitors (NRTI).

METHODS

A time-to-event analysis was performed using data from the Delta trial to study the incidence of PN in HIV-infected individuals receiving zidovudine (AZT) alone or in combination with didanosine (ddl) or zalcitabine (ddC). In an on-treatment analysis, changes in the incidence of PN by duration of treatment were directly estimated using a flexible parametric survival model.

RESULTS

A total of 3,195 patients (total follow-up 4,593 person-years) were included in the analysis. AZT+ddC was associated with a higher incidence of PN (6.2 cases/100 person-years) compared with AZT monotherapy (3.0 cases/100 person-years) and AZT+ddl (2.2 cases/100 person-years). The risk of PN peaked around day 90 following randomization (at 8.9 events/100 person-years in the AZT+ddC arm). PN was also associated with age at entry (hazard ratio (HR)=2.35 for those aged 35-44 years compared with <30) and current CD4+ T-cell count (HR=2.27 for CD4+ T-cell counts <150 cell/mm3 compared with >350).

CONCLUSION

Our findings challenge the common supposition that PN arises from cumulative exposure to NRTIs. We found that patients who developed PN tended to do so shortly after exposure to antiretroviral therapy. Therefore, our results support the hypothesis of a susceptibility in a subgroup of patients. These results will be of direct interest to those working in resource-limited countries where potentially neurotoxic dideoxynucleosides are still widely used.

Poor efficacy and tolerability of stavudine, didanosine, and efavirenz-based regimen in treatment-naive patients in Senegal

OBJECTIVE

To study the effectiveness and tolerance of an antiretroviral therapy (ART) regimen composed of the antiretroviral agents (ARVs) stavudine (d4T) plus didanosine (ddI) plus efavirenz (EFV) in patients with advanced HIV infection in Senegal.

DESIGN AND METHODS

This was an open-label, single-arm, 18-month trial in treatment-naive patients. The primary virologic end point was the percentage of patients with plasma HIV RNA < 500 copies/mL at months 6 (M6), 12 (M12) and 18 (M18). The primary analysis was done as intent-to-treat.

RESULTS

The staging of HIV disease, performed using the definitions of the US Centers for Disease Control and Prevention (CDC), was CDC stage B or C for all 40 recruited patients. At baseline, the mean CD4+ cell count was 133 +/- 92/mcL (+/- standard deviation [SD]; range 1-346), and 23% of patients had CD4+ cell counts below 50/mcL. The mean baseline plasma HIV RNA level was 5.5 +/- 0.4 log(10) copies/mL (+/- SD; range 4.6-5.9). The proportion of patients with plasma HIV-1 RNA below 500 copies/mL fell during the study from 73% (95% CI [56; 85]) at M6 to 56% (95% CI [41; 73]) at M12 and 43% (95% CI [27; 59]) at M18. Plasma HIV-RNA was below 50 copies/mL in 50% of study subjects (95% CI [31; 66]) at M6, 43% (95% CI [27; 59]) at M12, and 33% (95% CI [19; 49]) at M18. The mean increase in the CD4+ cell count was 105 +/- 125/mcL (n = 38) at M3 and 186 +/- 122/mcL (n = 21) at M18. Eight patients died, including 6 because of infectious complications. The last viral load (VL) value before death was < 500 copies/mL in all these patients except 1 nonadherent patient. Fifteen patients (37.5%) had peripheral neuropathy that was severe enough in 5 patients (12.5%) to require ddI and d4T discontinuation.

CONCLUSION

Virologic efficacy combination therapy with d4T, ddI, and EFV was measured by the percentage of patients with plasma HIV RNA values below 500 copies/mL and 50 copies/mL; for both parameters, virologic efficacy decreased during the study period. This is explained by the high mortality rate (20%) and treatment modifications due to adverse events (13%). These data strengthen the recently revised World Health Organization (WHO) guidelines advocating initiation of highly active antiretroviral therapy (HAART) before profound CD4 lymphocyte depletion occurs and avoiding HAART regimens containing d4T and ddI because of treatment-limiting side effects.

Didanosine enteric-coated capsule: current role in patients with HIV-1 infection

Didanosine, which is a synthetic nucleoside analogue intracellularly phosphorylated to the active metabolite, inhibits the activity of HIV-1 reverse transcriptase by competing with the natural substrate. Currently, didanosine is mainly provided as an enteric-coated capsule. In vitro, the molecule is active against laboratory strains and clinical isolates of HIV-1 in resting and activated T cells and monocyte/macrophages. Didanosine may select for resistance mutations that may render the drug inactive against the virus; L74V and K65R remain as the main didanosine-related mutations. In vitro, phenotypic susceptibility to didanosine was decreased beyond a defined fold change clinical cut-off (1.7), and it is considered that genotypic resistance exists when five thymidine-associated mutations or four plus M184V are present. In vivo, clinical studies have shown that didanosine retains significant antiviral activity in patients who have up to five nucleoside analogue mutations at baseline. Didanosine is useful in patients with no previous therapy, as well as in experienced patients in whom one or more antiretroviral regimens has failed.Enteric-coated didanosine is taken once daily, its co-administration with food has been recently evaluated and a reduction of the efficacy of the antiretroviral treatment was not observed. Administered with lamivudine (or emtricitabine), it can be considered a good alternative for use in the nucleoside analogue backbone included in combination therapies for antiretroviral-naive patients. Didanosine could be used in initial treatments for patients intolerant of zidovudine, abacavir or tenofovir. It can be included in once-daily combination regimens, which are more convenient and patient friendly.Prospective, observational and open-label studies, as well as clinical trials (with durations between 24 and 96 weeks), have demonstrated the safety and efficacy of didanosine plus lamivudine (or emtricitabine) plus efavirenz (or nevirapine) in previously untreated HIV-1-infected patients. The administration of didanosine to treatment-experienced patients has been evaluated in two different contexts: patients in whom previous therapies have failed (rescue therapy) and those with controlled viraemia who are switched to a didanosine-containing regimen for simplification.Adverse events associated with the administration of didanosine have been well known since the initial clinical trials with the drug. Gastrointestinal intolerance, peripheral neuropathy and hyperamylasaemia/pancreatitis were the most frequently reported. In the highly active antiretroviral therapy (HAART) era, the rate of adverse events has decreased. The tolerability of didanosine has been clearly improved with the development of the enteric-coated capsule. Severe manifestations of mitochondrial toxicity, including lactic acidosis and abnormal fat distribution, are rare complications, and occur most frequently when didanosine is used in combination with stavudine.

Long-term safety and efficacy of a once-daily regimen of emtricitabine, didanosine, and efavirenz in HIV-infected, therapy-naive children and adolescents: Pediatric AIDS Clinical Trials Group Protocol P1021

BACKGROUND

Compliance with complex antiretroviral therapy regimens is a problem for HIV-1-infected children and their families. Simple, safe, and effective regimens are important for long-term therapeutic success.

METHODS

A novel, once-daily dosing regimen of 3 antiretroviral drugs, emtricitabine, didanosine, and efavirenz, was tested in 37 therapy-naive HIV-infected children and adolescents between 3 and 21 years of age (inclusive). Subjects were followed for > or = 96 weeks on an intention-to-treat basis. Signs, symptoms, plasma HIV-1 RNA viral load, CD4 counts, and safety laboratories were followed regularly. End points were the proportion of subjects with plasma HIV < 400 or 50 HIV copies per mL and safety and tolerability of the regimen.

RESULTS

Thirty-seven subjects enrolled at 16 sites. Two subjects with rashes during the first 2 weeks of therapy were the only adverse events leading to study-drug discontinuation. Other early (before protocol-scheduled conclusion) study discontinuations included 3 viral failures on treatment and 5 patients who stopped therapy for apparently nonmedical reasons. Possible drug-related adverse events included 1 grade 4 low-glucose and 5 varied grade 3 events. There were no deaths. Virologic outcomes demonstrated that 32 (85%) of 37 subjects achieved viral suppression to < 400 RNA copies per mL, and 26 (72%) of 37 subjects maintained sustained suppression at < 50 copies per mL through week 96. The median baseline CD4 count was 310 per microL (17%), which increased at week 96 by a median of +329 cells per microL (by +18% CD4). Pharmacokinetic results were as predicted for emtricitabine, didanosine, and efavirenz capsules, whereas efavirenz concentrations in children receiving efavirenz oral solution were lower than anticipated, requiring a dose escalation after the planned assessment point.

CONCLUSIONS

A once-daily regimen of emtricitabine, didanosine, and efavirenz proved to be safe and tolerable and demonstrated good immunologic and virologic efficacy in this 2-year study.

Nucleoside reverse-transcriptase inhibitor dosing errors in an outpatient HIV clinic in the electronic medical record era

Information on antiretroviral dosing errors among health care providers for outpatient human immunodeficiency virus (HIV)-infected patients is lacking. We evaluated factors associated with nucleoside reverse-transcriptase inhibitor dosing errors in a university-based HIV clinic using an electronic medical record. Overall, older age, minority race or ethnicity, and didanosine use were related to such errors. Impaired renal function was more common in older patients and racial or ethnic minorities and, in conjunction with fixed-dose combination drugs, contributed to the higher rates of errors in nucleoside reverse-transcriptase inhibitor dosing. Understanding the factors related to nucleoside reverse-transcriptase inhibitor dosing errors is an important step in the building of preventive tools.

Amprenavir and didanosine are associated with declining kidney function among patients receiving tenofovir

OBJECTIVE

To examine the effect of antiretroviral agents and clinical factors on the development of tenofovir-associated kidney dysfunction.

METHODS

Observational cohort study of HIV-infected patients receiving tenofovir in an HIV clinic population. Patients' kidney function prior to initiating and while receiving tenofovir was evaluated in relation to other antiretroviral medications and demographic and clinical characteristics. Decline in kidney function was assessed by the glomerular filtration rate (GFR) as estimated by the Cockcroft-Gault (CG) equation, which incorporates weight. Logistic regression analysis was used to examine factors associated with GFR of > 90, 60-90, 30-60, and < 30 ml/min per 1.73 m(2) while on tenofovir. Secondary analyses used the simplified Modification of Diet in Renal Disease (MDRD) equation.

RESULTS

Among the 445 patients initiating tenofovir, 51 (11%) developed a decline in kidney function. In multivariate analysis, there was a significant association between decline in kidney function and concurrent use of amprenavir [odds ratio (OR) 3.6; P = 0.045] and didanosine (OR, 3.1; P = 0.006), age over 50 years (OR, 4.4; P = 0.03), and lower baseline weight (OR, 0.95/kg; P < 0.001). Patients identified with kidney dysfunction by the MDRD equation did not fully overlap with those identified by the CG equation.

CONCLUSIONS

Didanosine and amprenavir use, increased age, and lower baseline weight were significantly associated with risk for kidney dysfunction among patients receiving tenofovir. GFR results using the MDRD equation were inconsistent with those using CG, which highlights the impact of including weight in the estimation of GFR among HIV-infected patients.

Association of serum lipid levels with HIV serostatus, specific antiretroviral agents, and treatment regimens

BACKGROUND

The effects of HIV infection, highly active antiretroviral therapy (HAART), and specific antiretroviral agents on lipoproteins in women are not well described.

METHODS

In a cross-sectional substudy of the Women's Interagency HIV Study with 623 HIV-negative and 1556 HIV-positive women (636 untreated, 419 on non-protease inhibitor [PI] HAART, and 501 on PI-containing HAART), we performed multivariate analyses of associations among fasting lipoprotein levels, HIV infection, and HAART.

RESULTS

Untreated HIV-positive women had lower high-density lipoprotein cholesterol (HDL-C) and higher triglycerides (TGs) but not lower low-density lipoprotein cholesterol (LDL-C) than HIV-negative women and were the most likely to have unfavorable HDL-C by National Cholesterol Education Program (NCEP) guidelines. PI HAART users had higher LDL-C than untreated HIV-infected women (107 vs. 100 mg/dL, P = 0.0006) and were the most likely to have unfavorable LDL-C and TGs by NCEP guidelines. HIV-negative women and non-PI HAART users had similar HDL-C levels (55 and 53 mg/dL, respectively), which were higher than those in untreated HIV-infected women and PI HAART users (42 and 49 mg/dL, respectively; P < 0.001 for all). Lamivudine, didanosine, nevirapine, and efavirenz were independently associated with higher HDL-C (P < 0.001 for all). Ritonavir, indinavir/ritonavir, and nelfinavir were associated with higher LDL-C (P < 0.01 for all). Stavudine, abacavir, and all ritonavir-containing regimens were associated with higher TGs (P < 0.05 for all), and tenofovir was associated with lower TGs (P = 0.009).

CONCLUSIONS

A dyslipidemic pattern was associated with HIV infection itself, was more severe in users of PI-containing HAART, but was not present in women taking non-PI HAART.

Antiretroviral therapies associated with lipoatrophy in HIV-infected women

We previously demonstrated that HIV infection is associated with peripheral and central lipoatrophy in women. We now describe the association of specific antiretroviral drugs (ARV) with body fat changes over a four-year period from 1999 to 2003. 775 HIV-positive and 205 HIV-negative women in the Women's Interagency HIV Study with anthropometric measurements, weight, bioelectric impedance analysis and ARV collected semiannually were included in analysis. Exposure to ARV was defined as report of use for 3 consecutive semiannual study visits. The average 6-month change in weight, percent total body fat, and circumference measurements (i.e., hip, waist, chest, arm, and thigh) was compared between those exposed and those unexposed to the specific ARV for any of the same three consecutive visits. Weight, percent total body fat, and hip, waist, thigh, chest, and arm circumferences decreased in HIV-positive women, but increased in HIV-negative women on average for every six-month interval over the 4-year study period. Among the HIV-positive women, didanosine was the only ARV associated with decreases in circumference measures in the hip (-0.65 cm, 95% confidence interval [CI]: -1.18, -0.12), waist (-0.71 cm, 95% CI: -1.37, -0.04), chest (-0.71 cm, 95% CI: -1.17, -0.26), and arm (-0.23 cm, 95% CI: -0.48, 0.03; p = 0.08). These prospective data suggest that fat loss continues to predominate in HIV-positive women and exposure to didanosine for at least 12 months may further worsen fat loss.

Transplacentally exposed human and monkey newborn infants show similar evidence of nucleoside reverse transcriptase inhibitor-induced mitochondrial toxicity

Effective reduction in maternal-fetal human immunodeficiency virus-1 (HIV-1) transmission has been achieved by administration of nucleoside reverse transcriptase inhibitors (NRTIs) during pregnancy, and although most exposed children are clinically normal at birth, mitochondrial dysfunction has been reported. To examine mitochondrial integrity on a molecular level, we evaluated mitochondrial morphology by electron microscopy (EM) and mitochondrial DNA (mtDNA) quantity in umbilical cords and cord blood from NRTI-exposed and unexposed human and monkey newborns. Human subjects included infants born to HIV-1-infected mothers who received Combivir (Zidovudine [AZT] plus Lamivudine [3TC]) (n = 9) or AZT plus Didanosine [ddI] (n = 2) during pregnancy, and infants born to HIV-1-uninfected mothers (n = 7). NRTI-exposed Erythrocebus patas monkey dams (n = 3 per treatment group) were given human-equivalent dosing regimens containing 3TC, AZT/3TC, AZT/ddI, or Stavudine (d4T)/3TC during gestation. Four infants born to unexposed patas dams served as controls. Mitochondria in umbilical cord endothelial cells from NRTI-exposed monkey and human infants showed substantial abnormal pathology by EM, the extent of which was quantified from coded photomicrographs and shown to be different (P < 0.05) from the unexposed monkey and human newborns. Significant (P < 0.05) mtDNA depletion was found in umbilical cords from both human and monkey NRTI-exposed infants and in human, but not in monkey, cord blood leukocytes. For umbilical cords, an increase in mitochondrial morphological damage correlated with reduction in mtDNA quantity in fetal monkeys (r = 0.94). The treatment-induced mitochondrial compromise in infant monkeys ranked as follows: d4T/3TC > AZT/ddI > AZT/3TC > 3TC. The study demonstrates that transplacental NRTI exposures induce similar mitochondrial damage in cord blood and umbilical cords taken from retroviral-uninfected monkey infants and from human infants born to HIV-1-infected women.

CD4+ cell count decline despite HIV suppression: a probable didanosine-valganciclovir interaction

OBJECTIVE

To describe a case of significant CD4+ cell decline despite complete viral suppression in an HIV-positive patient receiving didanosine and valganciclovir.

CASE SUMMARY

A 68-year-old woman diagnosed with HIV and cytomegalovirus (CMV) enteritis (CD4+ cell count 22 cells/mm(3), viral load 88,898 [4.95 log] copies/mL) was treated with valganciclovir and began lamivudine, didanosine, and lopinavir/ritonavir. Three months later, her viral load was less than 50 copies/mL and CD4+ cell count was 317 cells/mm(3). Over the next 9 months, her viral load remained suppressed, but the CD4+ cell count declined to 83 cells/mm(3) and she experienced ongoing symptoms of didanosine toxicity. Didanosine was replaced with abacavir, leading to a complete CD4+ cell recovery and resolution of symptoms.

DISCUSSION

Paradoxical declines in CD4+ cell counts have been reported in HIV-infected patients virally suppressed on tenofovir/didanosine regimens, presumably via inhibition of purine nucleoside phosphorylase (PNP) by tenofovir and enhancement of didanosine toxicity. Ganciclovir and its prodrug valganciclovir also inhibit PNP and increase didanosine concentrations; thus, a similar immunological effect with this combination is possible. This hypothesis is consistent with observations from a historic multicenter CMV retinitis study, where a negative CD4+ cell response was observed in patients receiving ganciclovir, while those treated with foscarnet experienced a CD4+ cell increase and a mortality advantage. Of the subjects who received any type of nucleoside therapy during this study, didanosine use was proportionally higher in the ganciclovir arm versus the foscarnet arm. According to the Naranjo probability scale, our patient experienced a probable adverse reaction associated with the combination of didanosine and valganciclovir.

CONCLUSIONS

Patients receiving didanosine-containing highly active antiretroviral therapy and ganciclovir or valganciclovir for treatment of CMV infection should be monitored for didanosine toxicity and unexpected CD4+ cell loss or failure of CD4+ cell recovery. Reduction of didanosine dosage or substitution with an alternative antiretroviral may be necessary.

Evaluation of Human Immunodeficiency Virus Type 1-Infected Chinese Patients Treated with Highly Active Antiretroviral Therapy for Two Years

The purpose of this study was to evaluate the long-term efficacy and safety of nevirapine in combination with didanosine and stavudine in the treatment of human immunodeficiency virus (HIV)1-infected Chinese patients in routine clinical practice. The study, from April 2003 to May 2005, with follow-up through 24 mo, was conducted at the Department of Infectious Diseases, Second Xiangya Hospital, Central-South University in Changsha, Hunan Province, China. Twenty-seven HIV1-infected patients received didanosine, stavudine, and nevirapine. Information from case notes regarding age, sex, side effects, viral load, naive and memory T cells, and CD4(+) and CD8(+) T cell count at baseline, 3, 6, 12, 18, and 24 mo was collected and analyzed. Virologic suppression, defined as an HIV RNA concentration of less than 50 copies/mL at months 3, 6, 12, 18, and 24, was considered the main outcome measure. Of 27 patients, 17 were men with a mean age 33.5 yr. The mean baseline viral load was 5.15 log copies/mL and the mean CD4(+) cell count was 185 cells/dL. Of 27 patients, 3 patients discontinued study medication; treatment was changed, because of side effects, from didanosine (ddI), stavudine (d4T), and nevirapine (NVP) to zidovudine, lamivudine, and NVP for 24 patients who had completed 24 mo of treatment with ddI, d4T, and NVP; and viral load suppression was attained in 17 patients (70.8%) at 12 mo, in 14 patients (58.3%) at 18 mo, and in 13 patients (56.6%) at 24 mo. The CD4 T cell count increased by 114 cells/microL (mean, 299 cells/microL) after 12 mo of treatment and by 132 cells/microL (mean, 317 cells/microL) after 24 mo of treatment. Naive T cells and memory cells also increased in number, but at a slower rate. Activated (CD38(+)) CD8(+) T cells were elevated at baseline (67.7%) and declined by month 24 (49.7%), but did not reach normal levels. We conclude that a regimen of NVP with ddI and d4T provided durable suppression of plasma viral load in HIV-infected patients, with significant improvement in the CD4 cell count, and can be well tolerated by patients with HIV-1 infection.

Metabolic and anthropometric changes one year after switching from didanosine/stavudine to tenofovir in HIV-infected patients

BACKGROUND

Nucleoside analogues such as Didanosine and Stavudine are known to cause metabolic and body habitus changes during antiretroviral therapy. The most frequently observed are lactic acidosis, hypercholesterinaemia, hypertriglyceridaemia and lipodystrophy.

METHODS

Over one year we monitored a cohort of 43 patients who switched from either Stavudine, Didanosine or the combination of both to Tenofovir. A group of 11 patients was kept on their original regimen and acted as control group. Blood samples were taken every 3 months from baseline, anthropometric measurements were performed at baseline, after 6 and 12 months.

RESULTS

During observation the levels of lactic acid and cholesterol decreased significantly in the switch group while virologic and immunologic efficacy remained stable. Serum creatinine levels rose significantly in patients switched to Tenofovir, but remained within physiological limits. The mean skin fold thickness increased significantly by 1.8 mm in the switch group after 6 months (p < or =0.001 - p = 0.032).

CONCLUSION

These results implicate an improvement of lipid profiles, serum lactate and lipodystrophy in HIV-positive patients after switch to Tenofovir. As a moderate increase in serum creatinine levels was observed, the renal function of patients on a Tenofovir-based regimen should be monitored closely.

Severity of the toxicity associated with combinations that include didanosine plus stavudine in HIV-infected experienced patients

BACKGROUND

The combination of didanosine (ddI) and stavudine (d4T) is no longer recommended as a first-line treatment because of toxicity, but it may be useful in experienced patients.

METHODS

Retrospective chart review of experienced patients on ddI plus d4T was conducted at a single institution, recording the development of adverse events as well as their severity and action taken. The risk of developing severe toxicities was estimated by Kaplan-Meier analysis.

RESULTS

A total of 616 patients were on ddI plus d4T for a median time of 12 months (interquartile range: 5.0-24.7 months). Among them, 213 (34.6%) had AIDS, 161 (27.4%) had CD4 counts <200 cells/mm, and 503 (81.2%) had >2 previous treatment failures. Adverse events related to ddI plus d4T were recorded in 136 patients (22.1%), which were mild to moderate in 118 (19.1%) patients and severe in 18 (2.9%) patients. The mean times to development of severe and nonsevere adverse events were 72 (95% confidence interval [CI]: 70 to 75) weeks and 52 (95% CI: 48 to 55) weeks, respectively. The probability of developing severe adverse events was related to the nadir CD4 count, with higher risk in patients with <200 cells/mm (log rank test, P = 0.045).

CONCLUSIONS

Multiexperienced patients treated with combinations, including ddI plus d4T, frequently develop drug-related toxicity, but these events are rarely severe. Thus, these drugs can still be considered a valid option for salvage regimens.

Tenofovir plus didanosine as Nrti backbone in HIV-infected subjects

Nucleoside reverse transcriptase inhibitors (NRTI) are essential components of highly active antiretroviral treatment (HAART). Although several combinations can be used as NRTI backbones, not all are associated with good virological and/or immunological results. In particular, some NRTI combinations should be avoided due to antagonism (zidovudine plus stavudine) or to high rate of toxicity (didanosine plus stavudine). Tenofovir (TDF) and didanosine (ddI) are among the more often prescribed NRTI for their convenient posology (one pill each per day), relatively high genetic barrier for resistance, quite acceptable safety profile and remarkable antiviral potency when such drugs have been used as single drug or in combinations with other NRTIs. However, antiretroviral regimens containing TDF and ddI have been associated with a high rate of virological failure in HIV-infected naïve patients due to possible drug-interactions. The virological efficacy of this backbone in HIV-infected, HAART pre-treated subjects, is still controversial. Aim of this review is to assess the possible role that antiretroviral regimens containing TDF and ddI can have in the treatment of HIV-positive subjects, focusing on their plasmatic and/or intracellular interactions to optimize the antiretroviral efficacy and minimize the toxicities of this combination.