Hybrids of delavirdine and piperdin-4-yl-aminopyrimidines (DPAPYs) as potent HIV-1 NNRTIs: Design, synthesis and biological activities.

The hybrids of delavirdine and piperdin-4-yl-aminopyrimidine (DPAPYs) were designed from two excellent HIV-1 NNRTIs delavirdine and piperidin-4-yl-aminopyrimidine via molecular hybridization. The target compounds 4a-r were prepared and evaluated for their cellular anti-HIV activities and cytotoxicities as well as the inhibitory activities against HIV-1 reverse transcriptase (RT). All the newly synthesized compounds demonstrated moderate to excellent potency against wild-type (WT) HIV-1 with EC50 values in a range of 5.7 to 0.0086 µM and against RT with IC50 values ranging from 12.0 to 0.11 µM, indicating that the DPAPYs were specific RT inhibitors. Among all, 4d displayed the most potent activity against WT HIV-1 (EC50 = 8.6 nM, SI = 2151). Gratifyingly, it exhibited good to excellent potency against the single HIV-1 mutants L100I, K103N, Y181C, Y188L, E138K, as well as the double mutant F227L + V106A. Furthermore, the preliminary structure-activity relationships were summarized, molecular modeling was conducted to explore the binding mode of DPAPYs and HIV-1 RT, and their physicochemical properties were also predicted.

In silico design, synthesis and anti-HIV activity of quinoline derivatives as non-nucleoside reverse transcriptase inhibitors (NNRTIs).

A series of quinoline derivatives has been designed, synthesized and screened for their anti-HIV properties. The drug-like properties of compounds were evaluated first and then molecular docking using DS v20.1.0.19295 software showed that the compounds behaved as non-nucleoside reverse transcriptase inhibitors (NNRTIs) while interacting at the allosteric site of target HIV-RT protein (PDB:3MEC). The docking results revealed that all compounds formed hydrogen bonds with Lys101, Lys103, Val179, Tyr188, Gln190, Gly190, Pro225, Phe227, and Tyr318, and showed π-interaction with Tyr188 and Tyr318. TOPKAT (Toxicity Prediction by Komputer Assisted Technology) results confirmed that the compounds were found to be less toxic than the reference drugs. Density functional theory (DFT) analysis was performed to assess the binding affinity of all compounds. Further, molecular dynamics (MD) simulations were performed on compound 6 and delavirdine with HIV-RT enzyme. Comprehensive MD analyses showed a similar pattern of conformational stability and flexibility in both the complexes suggesting alike inhibitory action. The hydrogen-bonding interactions and the binding energy of active-site residues for the compound 6 complex revealed strong inhibitory activity than the reference (delavirdine) complex. Thus, the compound 6 might act as a potential inhibitor against HIV-RT. Overall, this study revealed that compound 6 (5-hydroxy-N-(4-methyl-2-oxo-1,2-dihydroquinolin-8-yl) thiophene-2-sulfonamide) has prudent anti-HIV activity against both HIV-1 (SI = 2.65) and HIV-2 (SI = 2.32) that can further be utilised in drug discovery against HIV virus.

Prevalence of predicted resistance to doravirine in HIV-1-positive patients after exposure to non-nucleoside reverse transcriptase inhibitors.

This study investigated the prevalence of doravirine (DOR) resistance mutations in non-nucleoside reverse transcriptase inhibitor (NNRTI)-experienced patients. DOR resistance was assessed in samples from NNRTI-experienced patients who underwent genotypic testing for virological failure from the Antiretroviral Response Cohort Analysis (ARCA) database. Intermediate DOR resistance was defined as detection of any of V106A/M, Y188C/H, V108I, and K103N+P225H. High-level DOR resistance was defined as detection of any of Y188L, M230L, G190E, V106A/M+F227L, and V106A/M+L234I. Overall, 6893 patients were included in the study: 64.2% had experienced efavirenz (EFV), 54.4% nevirapine (NVP), 6.8% etravirine (ETR), 7.7% rilpivirine (RPV) and 0.7% delavirdine. Among NNRTI-experienced patients, 12.7% and 6.1% of subjects had intermediate and high-level DOR resistance, respectively. The most common DOR resistance mutation was Y188L. In multivariable analysis, previous EFV use (OR = 1.52, 95% CI 1.15-2.02) and ETR use (OR = 1.91, 95% CI 1.34-2.73) were associated with detection of high-level DOR resistance, whilst RPV use was associated with a lower probability of high-level DOR resistance (OR = 0.39, 95% CI 0.22-0.71). Moreover, EFV use (OR = 1.76, 95% CI 1.19-2.58) and ETR use (OR = 1.72, 95% CI 1.10-2.68) were associated with detection of the Y188L mutation, whereas RPV use was not (OR = 0.16, 95% CI 0.05-0.50). In Italy, DOR resistance is uncommon among NNRTI-experienced patients, confirming a distinguishing resistance pattern within NNRTIs. However, previous EFV and ETR experience poses a higher risk of DOR resistance. These results support the use of DOR in NNRTI-experienced patients.

Important pharmacogenomic aspects in the management of HIV/AIDS

In managing HIV/AIDS with highly active antiretroviral agents, the historical therapeutic aim remains to maintain the plasma concentrations at a level above the half maximal inhibitory concentration (IC50) required for 50% inhibition in viral replication.Concentration dependent toxicity is often observed in patients with elevated drug exposure and high peak plasma levels in lieu of accurately calculated drug dosages. Similarly lowplasmaconcentrationsarefrequently witnessed in individuals receiving adequate dosage regimens. Pharmacogenetic variations in drug metabolizing enzymes may contribute to this phenomenon.Over the last decade, knowledge about the role of pharmacogenetics in the treatment and prediction of ARV plasma levels have increased significantly. However, the extent of these genetic variations remain largely unknown in the South African population,which has sparked a renewed enthusiasm forlocalpharmacogenetic studies

An accelerated background subtraction algorithm for processing high-resolution MS data and its application to metabolite identification.

BACKGROUND: Metabolite identification without radiolabeled compound is often challenging because of interference of matrix-related components. RESULTS: A novel and an effective background subtraction algorithm (A-BgS) has been developed to process high-resolution mass spectral data that can selectively remove matrix-related components. The use of a graphics processing unit with a multicore central processing unit enhanced processing speed several 1000-fold compared with a single central processing unit. A-BgS algorithm effectively removes background peaks from the mass spectra of biological matrices as demonstrated by the identification of metabolites of delavirdine and metoclopramide. CONCLUSION: The A-BgS algorithm is fast, user friendly and provides reliable removal of matrix-related ions from biological samples, and thus can be very helpful in detection and identification of in vivo and in vitro metabolites.

Antileishmanial activity of antiretroviral drugs combined with miltefosine.

Co-infection of Leishmaniasis, a neglected tropical disease, with human immunodeficiency virus (HIV) has hindered treatment efficacy. In this study, we aim to evaluate the antileishmanial activity of two protease inhibitors (darunavir and atazanavir) and four reverse transcriptase inhibitors (tenofovir, efavirenz, neviraprine, and delavirdine mesylate) on Leishmania infantum. The activity of different antiretrovirals combinations and of antiretroviral with miltefosine, a drug used on leishmaniasis treatment, was also evaluated. Only two non-nucleoside reverse transcriptase inhibitors (NNRTIs) were active on L. infantum. Efavirenz showed the best antileishmanial activity on promastigotes cells with IC50 value of 26.1 µM followed by delavirdine mesylate with an IC50 value of 136.2 µM. Neviraprine, tenofovir, atazanavir, and darunavir were not active at the concentrations tested (IC50 > 200 µM). The efavirenz also showed high antileishmanial activity on intramacrophage amastigotes with IC50 of 12.59 µM. The interaction of efavirenz with miltefosine improved antileishmanial activity on promastigotes and intracellular amastigotes (IC50 values of 11. 8 µM and 8.89 µM, respectively). These results suggest that combined-therapy including efavirenz and miltefosine could be alternative options for treating Leishmaniasis and Leishmania/HIV co-infections.

Role of the K101E substitution in HIV-1 reverse transcriptase in resistance to rilpivirine and other nonnucleoside reverse transcriptase inhibitors.

Resistance to the recently approved nonnucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine (RPV) commonly involves substitutions at positions E138K and K101E in HIV-1 reverse transcriptase (RT), together with an M184I substitution that is associated with resistance to coutilized emtricitabine (FTC). Previous biochemical and virological studies have shown that compensatory interactions between substitutions E138K and M184I can restore enzyme processivity and the viral replication capacity. Structural modeling studies have also shown that disruption of the salt bridge between K101 and E138 can affect RPV binding. The current study was designed to investigate the impact of K101E, alone or in combination with E138K and/or M184I, on drug susceptibility, viral replication capacity, and enzyme function. We show here that K101E can be selected in cell culture by the NNRTIs etravirine (ETR), efavirenz (EFV), and dapivirine (DPV) as well as by RPV. Recombinant RT enzymes and viruses containing K101E, but not E138K, were highly resistant to nevirapine (NVP) and delavirdine (DLV) as well as ETR and RPV, but not EFV. The addition of K101E to E138K slightly enhanced ETR and RPV resistance compared to that obtained with E138K alone but restored susceptibility to NVP and DLV. The K101E substitution can compensate for deficits in viral replication capacity and enzyme processivity associated with M184I, while M184I can compensate for the diminished efficiency of DNA polymerization associated with K101E. The coexistence of K101E and E138K does not impair either viral replication or enzyme fitness. We conclude that K101E can play a significant role in resistance to RPV.

Synthesis and biological evaluation of pyridazine derivatives as novel HIV-1 NNRTIs.

In continuation of our efforts toward identification and optimization of novel non-nucleoside reverse transcriptase inhibitors (NNRTIs), we have employed a structure-based bioisosterism strategy, with which a new series of diarylpyridazine (DAPD) derivatives were synthesized and evaluated for their anti-HIV-1 (human immunodeficiency virus type 1) activity. Most of the title compounds displayed excellent anti-HIV-1 activity at submicromolar concentrations ranging from 34 nM to 5.08 µM. The most promising compound 8g inhibited HIV-1 IIIB in MT-4 cells at a low EC50 value (0.034 µM), which was lower than the reference drug nevirapine and delavirdine. The structure activity relationships (SARs) were discussed and rationalized by docking simulations.

Methylmethacrylate-sulfopropylmethacrylate nanoparticles with surface RMP-7 for targeting delivery of antiretroviral drugs across the blood-brain barrier.

This study investigates the capability of methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) nanoparticles (NPs) with grafted RMP-7 (RMP-7/MMA-SPM NPs) to deliver stavudine (D4T), delavirdine (DLV), and saquinavir (SQV) across the blood-brain barrier (BBB). The permeability coefficients of the three drugs across the BBB were evaluated by a co-culture model containing human brain-microvascular endothelial cells and human astrocytes. An increase in the concentration of ammonium persulfate (APS), the polymerization initiator, enhanced the particle size of drug-loaded RMP-7/MMA-SPM NPs. When the concentration of APS was 0.6%, the average particle diameter was smaller than 50 nm. These spherical drug carriers were uniform in size and displayed a dominant topography of discrete hillocks and deep pits in deposited film. Smaller RMP-7/MMA-SPM NPs yielded a larger drug loading efficiency. The order of drug in the loading efficiency and in the particle uptake was, respectively, D4T>DLV>SQV and D4T>SQV>DLV. Endocytosis of RMP-7/MMA-SPM NPs and tight junction mediation can improve the permeability of D4T, DLV, and SQV across the BBB.

Solid lipid nanoparticles comprising internal Compritol 888 ATO, tripalmitin and cacao butter for encapsulating and releasing stavudine, delavirdine and saquinavir.

Solid lipid nanoparticles (SLNs) with complex internal phase were fabricated for formulating stavudine (D4T), delavirdine (DLV), and saquinavir (SQV). The lipids including Compritol 888 ATO, tripalmitin, and cacao butter were stabilized by L-α-phospatidylcholine, cholesteryl hemisuccinate, and taurocholate to form SLNs. The results revealed that the morphology of SLNs was spheroidal with shallow surface pits. An increase in the weight percentage of Compritol 888 ATO increased the average diameter of D4T-entrapping SLNs and decreased that of DLV- and SQV-entrapping SLNs. Preservation at 4°C over 6 weeks slightly enhanced the size of SLNs. For a specific drug, an increase in the entrapment efficiency enlarged the nanocarriers. The order of drug in the average particle diameter and in the entrapment efficiency was SQV>DLV>D4T, in general. In addition, the dissolution of the three drugs from SLNs showed the characteristics of sustained release. The order of drug in the cumulative release percentage was D4T>DLV>SQV. SLNs containing Compritol 888 ATO, tripalmitin, and cacao butter are efficient in carrying antiretroviral agents for medicinal application.

Human immunodeficiency virus type 1 resistance or cross-resistance to nonnucleoside reverse transcriptase inhibitors currently under development as microbicides.

Microbicides based on nonnucleoside reverse transcriptase inhibitors (NNRTIs) are currently being developed to protect women from HIV acquisition through sexual contact. However, the large-scale introduction of these products raises two major concerns. First, when these microbicides are used by undiagnosed HIV-positive women, they could potentially select for viral resistance, which may compromise subsequent therapeutic options. Second, NNRTI-based microbicides that are inactive against NNRTI-resistant strains might promote the selective transmission of these viruses. In order to address these concerns, drug resistance was selected in vitro by the serial passage of three viral isolates from subtypes B and C and CRF02_AG (a circulating recombinant form) in activated peripheral blood mononuclear cells (PBMCs) under conditions of increasing concentrations of three NNRTIs (i.e., TMC120, UC781, and MIV-160) that are currently being developed as candidate microbicides. TMC120 and MIV-160 displayed a high genetic barrier to resistance development, whereas resistance to UC781 emerged rapidly, similarly to efavirenz and nevirapine. Phenotypically, the selected viruses appeared to be highly cross-resistant to current first-line therapeutic NNRTIs (i.e., delavirdine, nevirapine, and efavirenz), although they retained some susceptibility to the more recently developed NNRTIs lersivirine and etravirine. The ability of UC781, TMC120, and MIV-160 to inhibit the in vitro-selected NNRTI-resistant viruses was also limited, although residual activity could be observed for the candidate microbicide NNRTI MIV-170. Interestingly, only four p2/p7/p1/p6/PR/RT/INT recombinant NNRTI-resistant viruses (i.e., TMC120-resistant VI829, EFV-resistant VI829, MIV-160-resistant VI829, and EFV-resistant MP568) showed impairments in replicative fitness. Overall, these in vitro analyses demonstrate that due to potential cross-resistance, the large-scale introduction of single-NNRTI-based microbicides should be considered with caution.

HIV-1 drug resistance among newly HIV-1 infected individuals attending tertiary referral center in Chennai, India.

CONTEXT: In the era of free HAART, accessibility and availability of ARV has been dramatically increased in India. However, rates of treatment literacy and adherence appear to be sub-optimal. Therefore, it is essential to monitor the extent of primary drug resistance in such settings. MATERIALS AND METHODS: Between July and October 2006, 18 anti-retroviral-naοve individuals were identified as recent infected by the BED-Capture enzyme immunoassay in a VCTC clinic in Chennai. Specimens from these individuals were subjected to genotypic drug resistance testing. Phylogenetic trees were generated using MEGA for Windows version 4.0 using neighbor-joining method. The significant differences in polymorphic mutation frequencies between the study specimens and established subtype C-specific polymorphisms were examined using the Chi-square test. RESULTS: Amino acid substitution (K103N and V106MV) at drug resistance positions occurred in two (11%) isolates, conferring high-level resistance to the non-nucleoside reverse-transcriptase inhibitors nevirapine (NVP), efavirenz (EFV), delavirdine (DLV) and notably extensive genetic variations were observed. K122E (94.4%) and K49R/KR (11.1%) polymorphisms identified in this study have not been previously described in established subtype-C specific polymorphisms. The rate of polymorphisms showed marked difference at the locations V60, D121, V35, and D123 (P < 0.0001). All the sequences showed maximum homology with Indian HIV-1 subtype C reference strain C.IN.95IN21068. CONCLUSIONS: The finding of resistance to NNRTIs is of public health importance. There is an urgent need to establish surveillance for primary drug resistance in large scale. Further studies are required to determine the phenotype impact of newer polymorphic mutations in relation to drug resistance and viral fitness.

The home as an appropriate setting for women undertaking cervical ripening before the induction of labour.

OBJECTIVES: to explore women's experiences of cervical ripening using isosorbide mononitrate (IMN) in the home as part of the main randomised controlled trial. DESIGN: qualitative study with semi-structured interviews carried out at three weeks post partum. Interview transcripts were analysed to identify recurrent themes, focusing on why women became involved in the study, their views about both the self-medication and the home setting, and whether they would repeat the experience. SETTING: the home. PARTICIPANTS: twenty women enrolled in the main randomised controlled trial. INTERVENTION: the study is part of a double-blind randomised controlled trial with 350 patients investigating whether a nitric oxide donor (IMN) used in cervical ripening improves the process of induction of labour. FINDINGS: women liked the opportunity to remain at home during the cervical ripening process. Timing and setting were central issues; women hoped that it would hasten labour, while the home was seen as a setting offering freedom, security and reassurance, as opposed to the hospital, seen as constraining. Two women reported problems with IMN but the remainder reported that they would repeat the experience. IMPLICATIONS FOR PRACTICE: women were very positive about the opportunity to undertake cervical ripening at home. It is important to explore this setting further for appropriate interventions.

Modifying the diffusion layer of soluble salts of poorly soluble basic drugs to improve dissolution performance.

The dissolution mechanism of soluble salts of poorly soluble bases can be complex because both the dissolution of the salt and precipitation of the free base can occur depending on the experimental conditions and properties of the molecule. The dissolution of three soluble salts of poorly soluble bases is described in this paper. Two of these compounds precipitate as free base under normal stomach pH conditions (pH from 2-4) during dissolution. This free base precipitation is a result of formation of free base on the surface of the dissolving salt. Diffusion Layer modulated (DLM) solids are defined and presented that can effectively counteract this precipitation mechanism. These DLM materials employ excipients in order to modify the pH or solubility conditions at the surface of the dissolving salt to minimize precipitation of the free base that can occur. Rotating disk dissolution data is presented which shows how these formulated solids can act to improve the dissolution profile for these materials.

Progress of bis(heteroaryl)piperazines (BHAPs) as non-nucleoside reverse transcriptase inhibitors (NNRTIs) against human immunodeficiency virus type 1 (HIV-1).

Since the first case of acquired immunodeficiency syndrome (AIDS) was reported in 1981, AIDS, as the global disease affecting 33.2 million people in 2007, has always been an unsolved problem worldwide. Reverse transcriptase (RT) is a crucial enzyme in the life cycle of human immunodeficiency virus type 1 (HIV-1), and thereby has been the prime drugs target for antiretroviral (ARV) therapy against AIDS. To date, two classes of RT inhibitors (RTIs), e.g., nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), and a lot of compounds tested as RTIs have been described. To our knowledge, bis(heteroaryl)piperazines (BHAPs) have been considered as one class of promising NNRTIs, such as structurally and chemically related NNRTI delavirdine, which was approved by the U. S. Food and Drug Administration (FDA) for the treatment of HIV-1 infection in 1997. In this mini-review, we make attempts to report the progress of synthesis and structure-activity relationship (SAR) of BHAPs, in the meantime, the synergistic inhibition of HIV-1 replication by combining delavirdine with other HIV-1 inhibitors is also discussed. It will pave the way for the design and development of BHAPs as anti-HIV-1 agents in AIDS chemotherapy in the future.

[Establishment of pharmacological evaluation system for non-nucleoside reverse-transcriptase inhibitors resistant HIV-1].

Consistent non-nucleoside reverse-transcriptase inhibitors (NNRTIs) resistant HIV-1 strains occurred due to the clinical use for more than ten years of efavirenz (EFV), nevirapine (NVP), and delavirdine (DLV). In this study, we established nine cell-based pharmacological models according to most NNRTIs-resistant clinical tested strains, Resistant mutations were introduced into vector, pNL4-3.Luc.R-E-, by overlapping PCR. Then, pseudovirions were produced by co-transfection of VSV-G plasmid and pNL4-3.Luc.R-E- -mut. All nine recombinant VSVG/HIV-mut pseudovirions (VSVG/HIV-wt, VSVG/HIV(-K103N), VSVG/HIV(-Y181C), VSVG/HIV(-L100I,K103N), VSVG/HIV(-Y188L), VSVG/HIV(-K103N,Y181C), VSVG/HIV(-K103N,P225H), VSVG/HIV(-K103N,Y188L), VSVG/HIV(-K103N,G109A) and VSVG/HIV(-K103N,V108I)) had high efficient infectivity. Furthermore, they all showed resistant characteristics to EFV and NVP with IC50 changes consisting with clinical reports, not to nucleoside reverse-transcriptase inhibitors (AZT and d4T). This series safe cell-based model, which could be carried out in BSL-2 laboratory, can be used for evaluating NNRTIs candidates.

A study of 3-substituted benzylidene-1,3-dihydro-indoline derivatives as antimicrobial and antiviral agents.

3-Substituted benzylidene-1,3-dihydro-indoline derivatives were tested for their in vitro antibacterial activity against the Gram-negative bacteria Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and the Gram-positive bacteria Bacillus subtilis, Staphylococcus aureus, and for their their in vitro antifungal activity against Candida krusei and Candida albicans. The minimum inhibitory concentration (MIC) values were determined by the 2-fold serial dilution technique in Mueller Hinton broth and Sabouraud dextrose agar using antibacterial and antifungal assays, respectively. For comparison of the antimicrobial activity, rifampicin, ampicillin trihydrate, gentamicin sulfate, and ofloxacin were used as reference antibacterial agents, and fluconazole and amphotericin B were employed as reference antifungal agents. The most active compound 10 showed notable inhibition against Bacillus subtilis, Staphylococcus aureus, and Candida krusei. Compounds 1 and 6 were found slightly effective against Klebsiella pneumoniae and Escherichia coli. In addition, compounds 13 and 14 showed inhibition against Bacillus subtilis and Staphylococcus aureus. Indole derivatives were also tested in vitro for replication of the HepAD38 cell line and compared with lamivudine (3TC, L-2',3'-dideoxy-3'-thiacytidine). The IC50 values of the compounds were found to be >1000 microM against HBV except for compound 13 which exhibited activity with an IC50 value of 500 microM.

The human immunodeficiency virus type 1 nonnucleoside reverse transcriptase inhibitor resistance mutation I132M confers hypersensitivity to nucleoside analogs.

We previously identified a rare mutation in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), I132M, which confers high-level resistance to the nonnucleoside RT inhibitors (NNRTIs) nevirapine and delavirdine. In this study, we have further characterized the role of this mutation in viral replication capacity and in resistance to other RT inhibitors. Surprisingly, our data show that I132M confers marked hypersusceptibility to the nucleoside analogs lamivudine (3TC) and tenofovir at both the virus and enzyme levels. Subunit-selective mutagenesis studies revealed that the mutation in the p51 subunit of RT was responsible for the increased sensitivity to the drugs, and transient kinetic analyses showed that this hypersusceptibility was due to I132M decreasing the enzyme's affinity for the natural dCTP substrate but increasing its affinity for 3TC-triphosphate. Furthermore, the replication capacity of HIV-1 containing I132M is severely impaired. This decrease in viral replication capacity could be partially or completely compensated for by the A62V or L214I mutation, respectively. Taken together, these results help to explain the infrequent selection of I132M in patients for whom NNRTI regimens are failing and furthermore demonstrate that a single mutation outside of the polymerase active site and inside of the p51 subunit of RT can significantly influence nucleotide selectivity.

Systematic review: Helicobacter pylori infection and impaired drug absorption.

BACKGROUND: Impaired acid secretion may affect drug absorption and may be consequent to corporal Helicobacter pylori-gastritis, which may affect the absorption of orally administered drugs. AIM: To focus on the evidence of impaired drug absorption associated with H. pylori infection. METHODS: Data sources were the systematic search of MEDLINE/EMBASE/SCOPUS databases (1980-April 2008) for English articles using the keywords: drug malabsorption/absorption, stomach, Helicobacter pylori, gastritis, gastric acid, gastric pH, hypochlorhydria, gastric hypoacidity. Study selection was made from 2099 retrieved articles, five studies were identified. Data were extracted from selected papers, investigated drugs, study type, main features of subjects, study design, intervention type and results were extracted. RESULTS: In all, five studies investigated impaired absorption of l-dopa, thyroxine and delavirdine in H. pylori infection. Eradication treatment led to 21-54% increase in l-dopa in Parkinson's disease. Thyroxine requirement was higher in hypochlorhydric goitre with H. pylori-gastritis and thyrotropin levels decreased by 94% after treatment. In H. pylori- and HIV-positive hypochlorhydric subjects, delavirdine absorption increased by 57% with orange juice administration and by 150% after eradication. CONCLUSIONS: A plausible mechanism of impaired drug absorption is decreased acid secretion in H. pylori-gastritis patients. Helicobacter pylori infection and hypochlorhydria should be considered in prescribing drugs the absorption of which is potentially affected by intragastric pH.