Saquinavir soft-gel capsule: an updated review of its use in the management of HIV infection

Antiviral drugs suppress infection of 2019-nCoV spike pseudotyped virus by interacting with ACE2 protein

The outbreak of coronavirus disease 2019 (COVID‐19) has induced a large number of deaths worldwide. Angiotensin‐converting enzyme 2 (ACE2) is the entry receptor for the 2019 novel coronavirus (2019‐nCoV) to infect the host cells. Therefore, ACE2 may be an important target for the prevention and treatment of COVID‐19. The aim of this study was to investigate the inhibition effect of valaciclovir hydrochloride (VACV), zidovudine (ZDV), saquinavir (SQV), and efavirenz (EFV) on 2019‐nCoV infection. The results of molecule docking and surface plasmon resonance showed that VACV, ZDV, SQV, and EFV could bind to ACE2 protein, with the K_D value of (4.33 ± 0.09) e⁻⁸, (6.29 ± 1.12) e⁻⁶, (2.37 ± 0.59) e⁻⁵, and (4.85 ± 1.57) e⁻⁵ M, respectively. But only ZDV and EFV prevent the 2019‐nCoV spike pseudotyped virus to enter ACE2‐HEK293T cells with an EC₅₀ value of 4.30 ± 1.46 and 3.92 ± 1.36 μM, respectively. ZDV and EFV also have a synergistic effect on preventing entry of virus into cells. In conclusion, ZDV and EFV suppress 2019‐nCoV infection of ACE2‐HEK293T cells by interacting with ACE2.

Inositols: From Established Knowledge to Novel Approaches

Myo-inositol (myo-Ins) and D-chiro-inositol (D-chiro-Ins) are natural compounds involved in many biological pathways. Since the discovery of their involvement in endocrine signal transduction, myo-Ins and D-chiro-Ins supplementation has contributed to clinical approaches in ameliorating many gynecological and endocrinological diseases. Currently both myo-Ins and D-chiro-Ins are well-tolerated, effective alternative candidates to the classical insulin sensitizers, and are useful treatments in preventing and treating metabolic and reproductive disorders such as polycystic ovary syndrome (PCOS), gestational diabetes mellitus (GDM), and male fertility disturbances, like sperm abnormalities. Moreover, besides metabolic activity, myo-Ins and D-chiro-Ins deeply influence steroidogenesis, regulating the pools of androgens and estrogens, likely in opposite ways. Given the complexity of inositol-related mechanisms of action, many of their beneficial effects are still under scrutiny. Therefore, continuing research aims to discover new emerging roles and mechanisms that can allow clinicians to tailor inositol therapy and to use it in other medical areas, hitherto unexplored. The present paper outlines the established evidence on inositols and updates on recent research, namely concerning D-chiro-Ins involvement into steroidogenesis. In particular, D-chiro-Ins mediates insulin-induced testosterone biosynthesis from ovarian thecal cells and directly affects synthesis of estrogens by modulating the expression of the aromatase enzyme. Ovaries, as well as other organs and tissues, are characterized by a specific ratio of myo-Ins to D-chiro-Ins, which ensures their healthy state and proper functionality. Altered inositol ratios may account for pathological conditions, causing an imbalance in sex hormones. Such situations usually occur in association with medical conditions, such as PCOS, or as a consequence of some pharmacological treatments. Based on the physiological role of inositols and the pathological implications of altered myo-Ins to D-chiro-Ins ratios, inositol therapy may be designed with two different aims: (1) restoring the inositol physiological ratio; (2) altering the ratio in a controlled way to achieve specific effects.

Predicting the Animal Susceptibility and Therapeutic Drugs to SARS-CoV-2 Based on Spike Glycoprotein Combined With ACE2

Recently, a few animals have been frequently reported to have been diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Whether they are SARS-CoV-2 intermediate hosts is worthy of great attention. The interaction of SARS-CoV-2 spike protein and its acceptor protein ACE2 is an important issue in determining viral host range and cross-species infection, while the binding capacity of Spike protein to ACE2 of different species is unknown. Here, we used the atomic structure model of SARS-CoV-2 and human ACE2 to assess the receptor utilization capacity of ACE2s from 10 kinds of animals. Results show that chimpanzees, domestic cats and cattles are more susceptible to infection by SARS-CoV-2. Cats in particular, such as pet cats and stray cats, interact very closely with humans, implying the necessity to carefully evaluate the risk of cats during the current COVID-19 pandemic. Furthermore, based on ACE2(cats)-SARS-CoV-2-RBD model, through high-throughput screening methods using a pool of 30,000 small molecules, eight compounds were selected for binding free energy calculations. All the eight compounds can effectively interfere with the binding of ACE2 and Spike protein, especially Nelfinavir, providing drug candidates for the treatment and prevention of SARS-CoV-2, suggesting further assessment of the anti-SARS-CoV-2 activity of these compounds in cell culture. Although we only reported the results of the simulation, and more laboratory and epidemiological investigation are required. Like cats are a risk factor, we can further detect SARS-CoV-2 according to the susceptibility of different animals, find the potential host of infection, and completely cut off the living space of the virus. Especially, cats could be a choice of animal model for screening antiviral drugs or vaccine candidates against SARS-CoV-2.

Enhancement of saquinavir absorption and accumulation through the formation of solid drug nanoparticles

Background

Nanotechnology is now considered a promising drug delivery method for orally administered hydrophobic drugs to their sites of action. The effect of nanodispersion on cellular transport and accumulation of saquinavir (SQV) was investigated.

Methods

The transport of five solid drug nanoparticle (SDN) SQV formulations along Caco-2 cell monolayers (CCM) was compared to that of standard SQV. The SDNs were prepared using SQV mesylate (20%), Pluronic F127 (10%) plus five other excipients (HPMC, PVP, PVA, Lecithin S75 and Span 80) in different proportions. Cellular accumulation in CEM parental and CEMVBL (P-gp overexpressing) cells was conducted to ascertain the effect of nanodispersion on P-gp mediated efflux of SQV. All SDN formulations were dissolved in water, whereas SQV in DMSO to improve solubility. Quantification was via HPLC.

Results

From transport results, an SDN sample composed of SQV mesylate/Pluronic F127 plus HPMC (70%) and had a 24% increase in apparent absorption compared to standard SQV, largely driven by a 38% reduction in basolateral to apical permeation. Additionally, the formulation and two others (SQV mesylate/Pluronic F127 alone; and + HPMC (65%)/Lecithin [5%]) accumulated more significantly in CEM cells, suggesting enhanced delivery to these cells. Moreover, accumulation and transport of the three SDNs compared well to that of SQV despite being dissolved in water, suggestive of improved dissolution. The inclusion of PVA resulted in increased efflux.

Conclusion

The use of HPMC and Pluronic F127 produced SQV SDNs with improved permeation in Caco-2 cells and improved accumulation in CEM cells, but negative effects with PVA.

Design strategies in the prodrugs of HIV-1 protease inhibitors to improve the pharmaceutical properties

Combination antiretroviral therapy (cART) is currently the most effective treatment for HIV-1 infection. HIV-1 protease inhibitors (PIs) are an important component of some regimens of cART. However, PIs are known for sub-optimal ADME properties, resulting in poor oral bioavailability. This often necessitates high drug doses, combination with pharmacokinetic enhancers and/or special formulations in order to effectively deliver PIs, which may lead to a high pill burden and reduced patient compliance. As a remedy, improving the ADME properties of existing drugs via prodrug and other approaches has been pursued in addition to the development of next generation PIs with improved pharmacokinetic, resistance and side effect profiles. Phosphate prodrugs have been explored to address the solubility-limiting absorption and high excipient load. Prodrug design to target carrier-mediated drug delivery has also been explored. Amino acid prodrugs have been shown to improve permeability by engaging active transport mechanisms, reduce efflux and mitigate first pass metabolism while acyl migration prodrugs have been shown to improve solubility. Prodrug design efforts have led to the identification of one marketed agent, fosamprenavir, and clinical studies with two other prodrugs. Several of the reported approaches lack detailed in vivo characterization and hence the potential preclinical or clinical benefits of these approaches are yet to be fully determined.

Targeting SVCT for enhanced drug absorption: synthesis and in vitro evaluation of a novel vitamin C conjugated prodrug of saquinavir

In order to improve oral absorption, a novel prodrug of saquinavir (Saq), ascorbyl-succinic-saquinavir (AA-Su-Saq) targeting sodium dependent vitamin C transporter (SVCT) was synthesized and evaluated. Aqueous solubility, stability and cytotoxicity were determined. Affinity of AA-Su-Saq towards efflux pump P-glycoprotein (P-gp) and recognition of AA-Su-Saq by SVCT were studied. Transepithelial permeability across polarized MDCK-MDR1 and Caco-2 cells were determined. Metabolic stability of AA-Su-Saq in rat liver microsomes was investigated. AA-Su-Saq appears to be fairly stable in both DPBS and Caco-2 cells with half lives of 9.65 and 5.73 h, respectively. Uptake of [(3)H]Saquinavir accelerated by 2.7 and 1.9 fold in the presence of 50 μM Saq and AA-Su-Saq in MDCK-MDR1 cells. Cellular accumulation of [(14)C]AA diminished by about 50-70% relative to control in the presence of 200 μM AA-Su-Saq in MDCK-MDR1 and Caco-2 cells. Uptake of AA-Su-Saq was lowered by 27% and 34% in the presence of 5mM AA in MDCK-MDR1 and Caco-2 cells, respectively. Absorptive permeability of AA-Su-Saq was elevated about 4-5 fold and efflux index reduced by about 13-15 fold across the polarized MDCK-MDR1 and Caco-2 cells. Absorptive permeability of AA-Su-Saq decreased 44% in the presence of 5mM AA across MDCK-MDR1 cells. AA-Su-Saq was devoid of cytotoxicity over the concentration range studied. AA-Su-Saq significantly enhanced the metabolic stability but lowered the affinity towards CYP3A4. In conclusion, prodrug modification of Saq through conjugation to AA via a linker significantly raised the absorptive permeability and metabolic stability. Such modification also caused significant evading of P-gp mediated efflux and CYP3A4 mediated metabolism. SVCT targeted prodrug approach can be an attractive strategy to enhance the oral absorption and systemic bioavailability of anti-HIV protease inhibitors.

Improved oral bioavailability and brain transport of Saquinavir upon administration in novel nanoemulsion formulations

The aim of this investigation was to develop novel oil-in-water (o/w) nanoemulsions containing Saquinavir (SQV), an anti-HIV protease inhibitor, for enhanced oral bioavailability and brain disposition. SQV was dissolved in different types of edible oils rich in essential polyunsaturated fatty acids (PUFA) to constitute the internal oil phase of the nanoemulsions. The external phase consisted of surfactants Lipoid-80 and deoxycholic acid dissolved in water. The nanoemulsions with an average oil droplet size of 100-200 nm, containing tritiated [(3)H]-SQV, were administered orally and intravenously to male Balb/c mice. The SQV bioavailability as well as distribution in different organ systems was examined. SQV concentrations in the systemic circulation administered in flax-seed oil nanoemulsions were threefold higher as compared to the control aqueous suspension. The oral bioavailability and distribution to the brain, a potential sanctuary site for HIV, were significantly enhanced with SQV delivered in nanoemulsion formulations. In comparing SQV in flax-seed oil nanoemulsion with aqueous suspension, the maximum concentration (C(max)) and the area-under-the-curve (AUC) values were found to be five- and threefold higher in the brain, respectively, suggesting enhanced rate and extent of SQV absorption following oral administration of nanoemulsions. The results of this study show that oil-in-water nanoemulsions made with PUFA-rich oils may be very promising for HIV/AIDS therapy, in particular, for reducing the viral load in important anatomical reservoir sites.

Efficacy of Low-Dose Boosted Saquinavir Once Daily Plus Nucleoside Reverse Transcriptase Inhibitors in Pregnant HIV-1-Infected Women With a Therapeutic Drug Monitoring Strategy

The efficacy of low-dose, ritonavir-boosted saquinavir (SQV/rtv) once daily plus 2 nucleoside retrotranscriptase inhibitors (NRTIs) in pregnant human immunodeficiency virus (HIV)-1-infected women was prospectively evaluated, ensuring a SQV minimum concentration (Cmin) >/=100 ng/mL with a therapeutic drug monitoring strategy. The primary clinical endpoint was the percentage of women with an HIV-RNA viral load (VL) of <50 copies/mL at the time of delivery. Forty-nine pregnancy episodes were included, with a median CD4 count and VL of 441/muL and 3710 copies/mL, respectively. Two patients were lost to follow-up and 1 patient discontinued treatment because of abdominal discomfort. SQV levels were in excess of the target Cmin in 43 of 46 episodes (93.4%) in which the end of pregnancy was reached on 1200/100 mg daily. The dosage was increased to 1600/100 mg in the remaining 3 episodes to achieve the target levels. By an intention-to-treat analysis, VL was undetectable at delivery in 43 episodes (87.7%; 95% confidence interval, 78.5-96.9) after a median of 18 weeks of treatment (range, 3-39). In the 3 episodes remaining, VLs of 110,400 copies/mL and no available data were observed after only 3 weeks of treatment. Mild adverse events attributable to SQV/rtv occurred in 6 of 49 pregnancies (12.2%). No cases of HIV vertical transmission were observed. The pharmacokinetics, efficacy, and tolerability of this regimen suggest that once-daily low-dose boosted SQV may be considered an appropriate option in PI-naive or limited-PI-experienced HIV-infected pregnant women. Nevertheless, therapeutic drug monitoring is advisable to maintain appropriate levels throughout pregnancy.

Oral contraception does not alter single dose saquinavir pharmacokinetics in women

AIMS

Women experience more adverse drug reactions (ADR) to antiretroviral therapy than men. This may be attributed to higher plasma concentrations of protease inhibitors due to pharmacokinetic interactions with hormonal preparations. Thus, in the present study we aimed to investigate the influence of oral contraceptives (OC) on the pharmacokinetics of the protease inhibitor saquinavir.

METHODS

Saquinavir was administered in a hard gelatin capsule formulation (Invirase) to rule out confounding by pharmaceutical aids of the more frequently used soft gelatin capsule. After an overnight fast, eight healthy female participants ingested a single oral dose of 600 mg saquinavir immediately before and after the 19th dose of a combined, low dose OC (0.03 mg ethinylestradiol, 0.075 mg gestodene) in a prospective, fixed sequence study design. The first saquinavir application was scheduled on day 1, 2, or 3 of the individual menstrual cycle. Plasma concentrations of saquinavir and relative concentrations of its M2&M3-hydroxy metabolites were determined by LC/MS/MS for 48 h.

RESULTS

Intake of OC resulted in a significant decrease in morning serum concentrations (before intake of OC, compared to day 19 of OC therapy) of 17beta-estradiol by -23.4 pg ml-1 (57%, 95%CI: -76% to -37.4%); progesterone by -0.25 ng ml-1 (33%, 95%CI: -45.3% to -21.5%); follicle-stimulating hormone by -4.06 U l-1 (82%, 95%CI: -96.5% to -67.7%); and luteinizing hormone by -3.49 U l-1 (74%, 95%CI: -93 to -54.6%). Conversely, sexual hormone binding globulin serum concentrations increased by 83.6 nmol l-1 (205%, 95%CI: 32.2% to 377%). Pharmacokinetic parameters of saquinavir (AUC, Cmax, tmax, t1/2, CLR) were not affected by OC, nor was the relative metabolic ratio of saquinavir/M2&M3-hydroxy saquinavir. Furthermore, there was no association of serum hormone concentrations or MDR1-polymorphisms (C3435T and G2677T) with pharmacokinetic parameters of saquinavir.

CONCLUSIONS

There was no effect of OC on saquinavir pharmacokinetics. Thus, pharmacokinetic interactions of synthetic sexual steroids with saquinavir are not likely to account for the increased ADR to antiretroviral therapy seen in women.

Saquinavir: a review of its use in boosted regimens for treating HIV infection

Protease inhibitor boosting involves concurrent administration of a protease inhibitor, such as saquinavir, plus a potent inhibitor of cytochrome P450 (CYP) 3A4, usually ritonavir in subtherapeutic doses. Since protease inhibitors are extensively metabolised by CYP3A4, this results in a marked increase in systemic exposure of saquinavir or other protease inhibitors boosted by ritonavir. As with traditional protease inhibitor regimens, boosted regimens are typically used in combination with nucleoside reverse transcriptase inhibitors (NRTIs). In protease inhibitor-experienced and -naive patients with HIV infection, twice-daily and once-daily boosted saquinavir regimens achieved good rates of viral suppression, improved CD4+ cell counts and were generally well tolerated in clinical trials. Encouraging results have also been reported in a number of small studies in heavily pretreated HIV-infected patients who received salvage therapy comprising double-boosted regimens of saquinavir plus lopinavir with subtherapeutic doses of ritonavir, along with other agents. The largest clinical trials have been multicentre, randomised comparisons of twice-daily boosted saquinavir versus twice-daily boosted indinavir (MaxCmin1) or lopinavir (MaxCmin2) regimens. In the MaxCmin1 study, >90% of patients in both groups had an undetectable viral load (<400 copies/mL) after 48 weeks of therapy in the on-treatment analysis. However, viral suppression was achieved in significantly more saquinavir than indinavir recipients in the intention-to-treat analysis, which appeared to be due to the significantly greater percentage of patients in the indinavir group who switched from randomised therapy because of adverse events. Interim 24-week results of the MaxCmin2 trial indicate that 90% of patients in both groups combined had plasma HIV RNA levels <400 copies/mL; final results at 48 weeks will report data separately for the boosted regimens of saquinavir and lopinavir.

CONCLUSION

Boosted protease inhibitor regimens (including two NRTIs) are recommended as a first-line option in current HIV treatment guidelines and are used extensively in clinical practice. The convenient administration schedule and good pharmacokinetic profile associated with boosted saquinavir regimens have the potential to increase adherence to therapy and improve antiretroviral effects through increased drug exposure. Twice-daily boosted saquinavir is one of the most extensively evaluated boosted protease inhibitor regimens and has been shown to have good efficacy on surrogate markers of HIV disease as well as significant tolerability advantages over boosted indinavir. Once-daily boosted saquinavir regimens may be most suitable for HIV-infected patients with busy lifestyles and those who would benefit from directly observed therapy.

The role of pharmacological enhancement in protease inhibitor-based highly active antiretroviral therapy

Having changed the landscape in the treatment of HIV infection, the functional efficacy of current protease inhibitors (PIs) remains limited by their pharmacokinetic and pharmacodynamic profiles. Complex metabolism by the cytochrome P450 system (particularly the 3A4 isoenzyme), action of membrane drug transporter elements (such as P-glycoprotein and multi-drug resistance-associated proteins) and activation of the nuclear receptor steroid xenobiotic receptor may alter exposures and compromise the antiretroviral activity of these drugs. These factors, as well as inadequate adherence, can facilitate the emergence of PI resistance and lead to regimen failure. Coadministration of ritonavir can enhance exposures of a primary PI by inhibiting CYP3A4 metabolism, P-glycoprotein activity and multi-drug resistance protein-1-mediated efflux. Adding ritonavir, however, is not without cost. Dyslipidaemia (possibly increasing the risk of cardiovascular events), gastrointestinal intolerance, multiple drug-to-drug interactions and activation of steroid xenobiotic receptor can all result and must be balanced against the pharmacokinetic improvement rendered by the addition of ritonavir. Understanding the pharmacological origins for the variations in exposures of PIs, both between and within patients, is important for the successful use of these agents.

The effect of ritonavir on saquinavir plasma concentration is independent of ritonavir dosage: combined analysis of pharmacokinetic data from 97 subjects

OBJECTIVE

To determine the correlation between ritonavir (RTV) dose and the degree of enhancement of saquinavir (SQV) exposure.

METHODS

Combined analysis of pharmacokinetic data at steady state obtained from two open-label, randomized, parallel-group, multiple-dose, single-centre studies involving healthy volunteers. Plasma samples for SQV assay were obtained from 97 healthy subjects following multiple dosing of a range of SQV (400-1800 mg) plus RTV (100-400 mg) dosages for 13-14 days. The pharmacokinetics of SQV were derived by model-independent, noncompartmental methods. Data were analysed by multivariate regression of log transformed Cmin and Cmax (geometric means) of SQV dosage as the dependent variable and independent variables of SQV and RTV dosage. Ritonavir was fitted as both a continuous and a categorical variable.

RESULTS

There is a strong effect of any dose of RTV on Cmax and Cmin of SQV (P < 0.0001 for both parameters), but no greater effect of higher vs. lower RTV dosages on either parameter (Cmax: P=0.4373; Cmin: P=0.3393). Higher SQV dosage correlates linearly with higher Cmax (P=0.0093) and Cmin (P=0.0010), but the effects of increasing SQV dosages are less than with the addition of any RTV dose.

CONCLUSIONS

RTV enhances SQV concentrations to increase Cmax and Cmin. This effect is similar for RTV dosages of 100-400 mg twice daily. Based on this concept of 'mini-dose' RTV, once-daily dosing of 1600 mg SQV/100 mg RTV and twice-daily 1000 mg SQV/100 mg RTV are currently being evaluated in clinical trials.

Pharmacokinetic and other drug interactions in patients with AIDS

A variety of medications are used in treating patients infected with the human immunodeficiency virus (HIV). These medications are used to control viremia and to prevent and treat opportunistic infections. An individual is often required to take numerous drugs at the same time and thus clinicians are confronted with potential drug interactions, some of which are significant. Three different groups of anti-HIV drugs are used to treat patients. These groups include nucleoside reverse transcription inhibitors, non-nucleoside reverse transcription inhibitors, and protease inhibitors. This article reviews the most relevant drug interactions that occur during the treatment of HIV-infected patients with traditional and also alternative drugs. The role of therapeutic drug monitoring in the routine management of HIV-infected patients is discussed.

High-performance liquid chromatography of HIV protease inhibitors in human biological matrices

Methods for HPLC analysis of protease inhibitors (PIs) in human biological matrices were reviewed. Assays have been developed for analysis of single PIs or for simultaneous measurement of multiple PIs in plasma-serum, saliva, cerebrospinal fluid and semen. Liquid-liquid extraction was most often applied for sample pretreatment, but solid-phase extraction and protein precipitation were used as well. Reversed-phase or ion-pair chromatography have been used to separate PIs. Detection of PIs should be sensitive enough for quantitation of plasma concentrations below trough levels of single PIs, or below proposed therapeutic thresholds for PIs. The large majority of assays employs UV detection. As the potential for interferences is large, the selectivity of every method should be evaluated properly. The available high-performance liquid chromatography (HPLC) methods have been applied in clinical pharmacokinetic studies and for therapeutic drug monitoring of PIs. Participation in an interlaboratory quality control program is recommended for every laboratory engaged in the bioanalysis of PIs.