The use of holding regimens for people living with HIV (PLWH) without effective antiretroviral options can have effects on outcomes and future treatment options. We aimed to investigate the use of holding regimens for PLWH in Asian countries. Data from adults enrolled in routine HIV care in IeDEA Asia-Pacific cohorts were included. Individuals were considered to be on holding regimen if they had been on combination antiretroviral therapy for at least 6 months, had two confirmed viral loads (VL) ≥1000 copies/mL, and had remained on the same medications for at least 6 months. Survival time was analyzed using Fine and Gray's competing risk regression. Factors associated with CD4 changes and VL <1000 copies/mL were analyzed using linear regression and logistic regression, respectively. A total of 425 PLWH (72.9% male; 45.2% high-income and 54.8% low-to-middle-income country) met criteria for being on a holding regimen. From high-income countries, 63.0% were on protease inhibitors (PIs); from low-to-middle-income countries, 58.4% were on non-nucleoside reverse transcriptase inhibitors (NNRTIs); overall, 4.5% were on integrase inhibitors. The combination of lamivudine, zidovudine, and efavirenz was the most commonly used single regimen (n = 46, 10.8%), followed by lamivudine, zidovudine, and nevirapine (n = 37, 8.7%). Forty-one PLWH (9.7%) died during follow-up (mortality rate 2.0 per 100 person-years). Age >50 years compared to age 31-40 years (sub-hazard ratio [SHR] 3.29, 95% CI 1.45-7.43, p = 0.004), and VL ≥1000 copies/ml compared to VL <1000 copies/mL (SHR, 2.14, 95% CI 1.08-4.25, p = 0.029) were associated with increased mortality, while higher CD4 counts were protective. In our Asia regional cohort, there was a diversity of holding regimens, and the patterns of PI vs. NNRTI use differed by country income levels. Considering the high mortality rate of PLWH with holding regimen, efforts to extend accessibility to additional antiretroviral options are needed in our region.
Zidovudine (ZDV) is converted to its active triphosphate (ZDVTP) by intracellular kinases. The intermediate ZDV monophosphate (ZDVMP) is believed to play a major role in ZDV toxicity. Manipulation of ZDV phosphorylation is a possible therapeutic strategy for altering the risk-benefit ratio. Here we investigate whether combining RBV with ZDV is able to modulate efficacy and toxicity of ZDV. We have measured the intracellular activation of ZDV (0.3 microM) in the absence and presence of ribavirin (RBV; 2 and 20 microM) in Molt 4 and U937 cells. MTT cytotoxicity of ZDV (10-1000 microM) was also measured with and without RBV (2 microM) in Molt 4 and U937 cells. Measurement of endogenous deoxythymidine triphosphate (dTTP) allowed investigation of the dTTP/ZDVTP ratio. The antiviral efficacy of ZDV in combination with RBV (2 microM) was assessed by HIV p24 antigen measurements. In the presence of RBV (2 and 20 microM) a decrease in total ZDV phosphates was observed, owing mainly to an effect primarily on ZDVMP rather than the active ZDVTP. RBV also increased endogenous dTTP pools in both cell types, resulting in an increase in the dTTP/ZDVTP ratio. ZDV alone significantly reduced p24 antigen production, with an IC50 of 0.34 microM. Addition of RBV increased the IC50 approximately fivefold (1.52 microM). However, at higher concentrations of ZDV (10 and 100 microM) the antagonistic effect of RBV (2 microM) on ZDV was lost. The RBV-mediated decrease in ZDVMP may explain the reduction in ZDV toxicity when combined with RBV (2 microM). Cytotoxicity of ZDV was reduced in the presence of RBV (2 microM) at all concentrations in both cell lines, probably owing to saturation of ZDVTP formation. The interaction of ZDV and RBV is concentration dependent.
1. Zidovudine (3'-azido-3'-deoxythymidine; AZT) is the drug of proven efficacy available for the treatment of patients with AIDS or ARC. It is eliminated mainly by hepatic glucuronidation. Therefore, interference with this metabolic pathway may lead to enhancement of AZT effect or to increased toxicity of the drug. We have examined the effect of a number of drugs which themselves undergo glucuronidation on AZT conjugation by human liver microsomes in vitro. 2. AZT glucuronidation followed Michaelis-Menten kinetics. The apparent Km and Vmax values (mean +/- s.d., n = 5), were 2.60 +/- 0.52 mM and 68.0 +/- 23.4 nmol h-1 mg-1, respectively, as determined from Eadie-Hofstee plots. 3. Dideoxyinosine, sulphanilamide and paracetamol were essentially non-inhibitory at concentrations up to 10 mM (4 times the concentration of AZT in the incubation). The most marked inhibitory effects were seen with indomethacin, naproxen, chloramphenicol, probenecid and ethinyloestradiol, with enzyme activity decreased by 97.7, 94.9, 88.7, 83.4% and 79.0%, respectively, at a concentration of 10 mM. Other compounds producing some inhibition of AZT conjugation were oxazepam, salicylic acid and acetylsalicylic acid. 4. Further studies are necessary to characterise the inhibition observed but the method described enables a screen of potentially important drug interactions to be carried out.
The co-use of conventional drug and herbal medicines may lead to herb-drug interaction via modulation of drug-metabolizing enzymes (DMEs) by herbal constituents. UDP-glucuronosyltransferases (UGTs) catalyzing glucuronidation are the major metabolic enzymes of Phase II DMEs. The in vitro inhibitory effect of several herbal constituents on one of the most important UGT isoforms, UGT2B7, in human liver microsomes (HLM) and rat liver microsomes (RLM) was investigated. Zidovudine (ZDV) was used as the probe substrate to determine UGT2B7 activity. The intrinsic clearance (Vmax/Km) of ZDV in HLM is 1.65 µL/mg/min which is ten times greater than in RLM, which is 0.16 µL/mg/min. Andrographolide, kaempferol-3-rutinoside, mitragynine and zerumbone inhibited ZDV glucuronidation in HLM with IC50 values of 6.18 ± 1.27, 18.56 ± 8.62, 8.11 ± 4.48 and 4.57 ± 0.23 µM, respectively, hence, herb-drug interactions are possible if andrographolide, kaempferol-3-rutinoside, mitragynine and zerumbone are taken together with drugs that are highly metabolized by UGT2B7. Meanwhile, only mitragynine and zerumbone inhibited ZDV glucuronidation in RLM with IC50 values of 51.20 ± 5.95 μM and 8.14 ± 2.12 µM, respectively, indicating a difference between the human and rat microsomal model so caution must be exercised when extrapolating inhibitory metabolic data from rats to humans.
Polymyxins are used as a last-line therapy against multidrug-resistant (MDR) New Delhi metallo-β-lactamase (NDM)-producing Klebsiella pneumoniae However, polymyxin resistance can emerge with monotherapy; therefore, novel strategies are urgently needed to minimize the resistance and maintain their clinical utility. This study aimed to investigate the pharmacodynamics of polymyxin B in combination with the antiretroviral drug zidovudine against K. pneumoniae Three isolates were evaluated in static time-kill studies (0 to 64 mg/liter) over 48 h. An in vitro one-compartment pharmacokinetic/pharmacodynamic (PK/PD) model (IVM) was used to simulate humanized dosage regimens of polymyxin B (4 mg/liter as continuous infusion) and zidovudine (as bolus dose thrice daily to achieve maximum concentration of drug in broth [Cmax] of 6 mg/liter) against K. pneumoniae BM1 over 72 h. The antimicrobial synergy of the combination was further evaluated in a murine thigh infection model against K. pneumoniae 02. In the static time-kill studies, polymyxin B monotherapy produced rapid and extensive killing against all three isolates followed by extensive regrowth, whereas zidovudine produced modest killing followed by significant regrowth at 24 h. Polymyxin B in combination with zidovudine significantly enhanced the antimicrobial activity (≥4 log10 CFU/ml) and minimized bacterial regrowth. In the IVM, the combination was synergistic and the total bacterial loads were below the limit of detection for up to 72 h. In the murine thigh infection model, the bacterial burden at 24 h in the combination group was ≥3 log10 CFU/thigh lower than each monotherapy against K. pneumoniae 02. Overall, the polymyxin B-zidovudine combination demonstrates superior antimicrobial efficacy and minimized emergence of resistance to polymyxins.
This prospective, observational, study evaluates the clinical outcomes, drug utilization patterns, and adherence to treatment of patients on highly active anti retroviral therapy (HAART) at a government institution in Kerala, India.
Matched MeSH terms: Zidovudine/economics; Zidovudine/therapeutic use
Figure 1 is a picture of a 48-year-old male patient who presents with progressive painful enlargement of the areolae of 10 months’ duration. There was no bleeding or nipple discharge. He was diagnosed with human immunodeficiency virus (HIV) infection 16 months ago and was initiated on antiretroviral therapy (ARV), which consisted of zidovudine, lamivudine and efavirenz. As his CD4 cell count at diagnosis was less than 200 cells/mm3, he was prescribed trimethoprim-sulphamethoxazole (Bactrim) for prophylaxis against pneumonia due to pneumocystis jirovecii. Physical examination was unremarkable except for bilateral breast enlargement and right-sided old shingles scar in the T4 dermatome distribution.