Cerebrospinal Fluid and Brain Tissue Penetration of Tenofovir, Lamivudine, and Efavirenz in Postmortem Tissues with Cryptococcal Meningitis

CNS Viral Infections-What to Consider for Improving Drug Treatment: A Plea for Using Mathematical Modeling Approaches

Neurotropic viruses may cause meningitis, myelitis, encephalitis, or meningoencephalitis. These inflammatory conditions of the central nervous system (CNS) may have serious and devastating consequences if not treated adequately. In this review, we first summarize how neurotropic viruses can enter the CNS by (1) crossing the blood-brain barrier or blood-cerebrospinal fluid barrier; (2) invading the nose via the olfactory route; or (3) invading the peripheral nervous system. Neurotropic viruses may then enter the intracellular space of brain cells via endocytosis and/or membrane fusion. Antiviral drugs are currently used for different viral CNS infections, even though their use and dosing regimens within the CNS, with the exception of acyclovir, are minimally supported by clinical evidence. We therefore provide considerations to optimize drug treatment(s) for these neurotropic viruses. Antiviral drugs should cross the blood-brain barrier/blood cerebrospinal fluid barrier and pass the brain cellular membrane to inhibit these viruses inside the brain cells. Some antiviral drugs may also require intracellular conversion into their active metabolite(s). This illustrates the need to better understand these mechanisms because these processes dictate drug exposure within the CNS that ultimately determine the success of antiviral drugs for CNS infections. Finally, we discuss mathematical model-based approaches for optimizing antiviral treatments. Thereby emphasizing the potential of CNS physiologically based pharmacokinetic models because direct measurement of brain intracellular exposure in living humans faces ethical restrictions. Existing physiologically based pharmacokinetic models combined with in vitro pharmacokinetic/pharmacodynamic information can be used to predict drug exposure and evaluate efficacy of antiviral drugs within the CNS, to ultimately optimize the treatments of CNS viral infections.

Clinical pharmacology of the SingleTablet Regimen (STR) Bictegravir/Emtricitabine/Tenofovir Alafenamide (BIC/FTC/TAF)

In Italy a proportion of HIV patients exceeding 50% are diagnosed at advanced stages of disease. A sizeable proportion of patients under chronic HIV treatment has a story of poor adherence with archived resistance associated mutations, a condition implying some risks in case of treatment with dual regimens. Conventional three-drug regimens will remain necessary in the short-mid term, in order to avoid treatment failure and selection of drug resistance. Efficacy, tolerability, safety, genetic barrier, forgiveness and a good compatibility with concurrent medications are all features that describe the overall quality of BIC/FTC/TAF, a combination whose robustness will remain a point of reference for the next years.

A post-mortem analysis of tenofovir, lamivudine, efavirenz and fluconazole penetration in female genital tissues

BACKGROUND

Optimal penetration of anti-infectives in the female genital tract (FGT) is paramount in the treatment and prevention of infectious diseases. While exposure of anti-infectives in lower FGT tissues (e.g. cervix, vagina) has been described, little data exist on upper genital tissues (e.g. ovary, uterus).

METHODS

Autopsies were performed and post-mortem tissues were collected within 24 h of death for female participants with advanced HIV in Uganda (n = 27). Tenofovir, lamivudine, efavirenz and fluconazole concentrations were measured using LC-MS/MS in plasma, ovarian, uterine, cervical and vaginal tissues. Tissue penetration was calculated as tissue-to-plasma concentration ratios (TPRs).

RESULTS

TPRs of tenofovir, lamivudine and fluconazole were highest in vaginal tissue (medians 1.86, 1.83 and 0.94, respectively), while the TPR of efavirenz was highest in ovarian tissue (median 0.65). With cervix as a reference compartment, vaginal TPRs were significantly higher than cervical for all four drugs; TPRs of efavirenz in uterine and ovarian compartments were also significantly higher than cervical. Most of the post-mortem FGT samples had a TPR of greater than 1 for tenofovir and lamivudine, while less than 50% had a TPR of greater than 1 for both efavirenz and fluconazole.

CONCLUSIONS

Penetration of anti-infectives was not homogeneous among the FGT compartments. Approximately 70% of FGT tissues had a TPR of greater than 1 for tenofovir and lamivudine, favouring the prevention of local HIV replication and transmission in the FGT.

Rates of refusal of clinical autopsies among HIV-positive decedents and an overview of autopsies in Uganda

Background: Human immunodeficiency virus (HIV)-related mortality remains high in sub-Saharan Africa. Clinical autopsies can provide invaluable information to help ascertain the cause of death. We aimed to determine the rate and reasons for autopsy refusal amongst families of HIV-positive decedents in Uganda. Methods: We consented the next-of-kin for post-mortem examinations among Ugandan decedents with HIV from 2017-2020 at Kiruddu National Referral Hospital. For those who refused autopsies, reasons were recorded. Results: In this analysis, 165 decedents with HIV were included from three selected wards at Kiruddu National Referral Hospital.  Autopsy was not performed in 45% of the deceased patients; the rate of autopsy refusal was 36%. The most common reasons for autopsy refusal were time constraints (30%), family satisfaction with clinical diagnosis (15%), fear of disfigurement of the remains (15%), and lack of perceived benefit (15%). By seeking consent from multiple family members and clearly explaining to them the purpose of performing the autopsy, we found a reduction in the rate of autopsy refusal among relatives of the deceased patients at this hospital compared to previous studies at the same site (36% vs. 60%). Conclusions: We found lower rates of autopsy refusal compared to previous studies at the same site. This underscores the importance of clearly explaining the purpose of autopsies as they increase active sensitization about their relevance and dispel myths related to autopsies among the general population. Good, culturally sensitive, and timely explanations to the family of the benefits of autopsy increase the rate of obtaining permission. Building capacity for performing autopsies by training more pathologists and increasing laboratory resources to decrease the turn-around-time for autopsy reports and extending these services to peripheral health facilities could improve autopsy acceptance rates.

Rates of refusal of clinical autopsies among HIV-positive decedents and an overview of autopsies in Uganda

Background: Human immunodeficiency virus (HIV)-related mortality remains high in sub-Saharan Africa. Clinical autopsies can provide invaluable information to help ascertain the cause of death. We aimed to determine the rate and reasons for autopsy refusal amongst families of HIV-positive decedents in Uganda. Methods: We consented the next-of-kin for post-mortem examinations among Ugandan decedents with HIV from 2017-2020 at Kiruddu National Referral Hospital. For those who refused autopsies, reasons were recorded. Results: In this analysis, 165 decedents with HIV were included from three selected wards at Kiruddu National Referral Hospital.  Autopsy was not performed in 45% of the deceased patients; the rate of autopsy refusal was 36%. The most common reasons for autopsy refusal were time constraints (30%), family satisfaction with clinical diagnosis (15%), fear of disfigurement of the remains (15%), and lack of perceived benefit (15%). By seeking consent from multiple family members and clearly explaining to them the purpose of performing the autopsy, we found a reduction in the rate of autopsy refusal among relatives of the deceased patients at this hospital compared to previous studies at the same site (36% vs. 60%). Conclusions: We found lower rates of autopsy refusal compared to previous studies at the same site. This underscores the importance of clearly explaining the purpose of autopsies as they increase active sensitization about their relevance and dispel myths related to autopsies among the general population. Good, culturally sensitive, and timely explanations to the family of the benefits of autopsy increase the rate of obtaining permission. Building capacity for performing autopsies by training more pathologists and increasing laboratory resources to decrease the turn-around-time for autopsy reports and extending these services to peripheral health facilities could improve autopsy acceptance rates.

Pharmacokinetics and tissue distribution of tenofovir, emtricitabine and dolutegravir in mice

BACKGROUND

Studies of antiretroviral drug (ARV) tissue distribution in preclinical models, such as mice, are key to understanding viral persistence.

OBJECTIVES

To determine the plasma and tissue pharmacokinetics and tissue distributions of tenofovir, emtricitabine and dolutegravir in mice.

METHODS

ARVs were simultaneously administered to two different strains, and their levels in plasma and tissue samples were determined by a validated LC-MS/MS method. A non-compartmental analysis was performed to estimate the main pharmacokinetic parameters. A tissue penetration factor (TPF) was calculated as the ratio of the concentration in the tissue concerned to that in plasma.

RESULTS

ARV plasma pharmacokinetic parameters in both strains were similar to those estimated in the clinical context. Tissue concentrations were highest in the digestive tract, followed by the liver and kidneys, lymphatic system, pancreas, adipose tissue and lungs. Tissue concentrations were lowest in the brain. Triple therapy could not be considered effective in any of the tissues considered. The TPF values obtained showed that tenofovir diffused widely, especially in the digestive tract, liver and kidneys. Emtricitabine had a TPF above 100% in two-thirds of the tissues. Dolutegravir was poorly distributed to all tissues.

CONCLUSIONS

Drug specificity was observed, with higher levels of exposure to tenofovir than to emtricitabine or dolutegravir. Tissue specificity was also observed, with strong penetration of the digestive tract and weak penetration of the brain. These data have important implications for future preclinical and clinical studies for developing new HIV therapies with the goal of an HIV cure.

Treating viruses in the brain: Perspectives from NeuroAIDS

Aggressive use of antiretroviral therapy has led to excellent viral suppression within the systemic circulation. However, despite these advances, HIV reservoirs still persist. The persistence of HIV within the brain can lead to the development of HIV-associated neurocognitive disorders (HAND). Although the causes of the development of neurocognitive disorders is likely multifactorial, the inability of antiretroviral therapy to achieve adequate concentrations within the brain is likely a major contributing factor. Information about antiretroviral drug exposure within the brain is limited. Clinically, drug concentrations within the cerebrospinal fluid (CSF) are used as markers for central nervous system (CNS) drug exposure. However, significant differences exist; CSF concentration is often a poor predictor of drug exposure within the brain. This article reviews the current information regarding antiretroviral exposure within the brain in humans as well as preclinical animals and discusses the impact of co-morbidities on antiretroviral efficacy within the brain. A more thorough understanding of antiretroviral penetration into the brain is an essential component to the development of better therapeutic strategies for neuroAIDS.