Absolute bioavailability and metabolic disposition of valaciclovir, the L-valyl ester of acyclovir, following oral administration to humans

Increasing hospitalisation of patients with herpes zoster ophthalmicus-an interdisciplinary retrospective analysis

BACKGROUND

The occurrence of herpes zoster is rising globally. Future trends will be influenced by changes in population demographics and the growing number of patients at risk. Overall this poses a challenge for healthcare systems.

METHODS

In our interdisciplinary, single-centre retrospective analysis, we aimed to assess the burden of the disease within the Department of Dermatology and the Eye Centre from the Medical Centre, University of Freiburg from 2009-2022. We obtained data from 3034 cases coded using the ICD-10 B02.x. Patients were characterised by sex, age, year of treatment, and type of treatment (inpatient vs. outpatient).

RESULTS

Overall we observed a 200% increase in the number of herpes zoster patients over the 13-year period. Upon closer analysis, this was mainly due to a rise in inpatient treatment for herpes zoster ophthalmicus.

CONCLUSIONS

If the incidence of herpes zoster ophthalmicus continues to increase at the current rate the number of hospitalisations of zoster ophthalmicus would double by 2040, assuming guideline-appropriate treatment. Overall, the results show a growing need for inpatient ophthalmological care.

Herpes simplex virus, varicella-zoster virus and cytomegalovirus keratitis: Facts for the clinician

Keratitis due to Herpes simplex virus (HSK), Varicella-Zoster virus (VZK) and Cytomegalovirus remains a frequent source of concern for many ophthalmologists. They are a frequent cause of emergency consultations at eye care centers and carry the risk of permanent loss of visual acuity or visual quality and/or chronic neurotrophic keratitis, resulting in a significant decrease in the quality of life. HSK and VZK can affect the corneal epithelium, stroma, or endothelium or a combination of layers. In contrast, most cases of CMV keratitis present as isolated endothelitis (CMVE), a clinical entity that has been described within the last 2 decades. These three types of viral keratitis are characterized by a high frequency of recurrences and each new episode increases the risk of sequelae. Hence, ophthalmologists must adapt the treatment to the clinical presentation of each recurrent episode in order to mitigate the immediate consequences of viral replication and the immune response on corneal transparency. In patients with frequent recurrences, preventive long-term antiviral treatment is strongly recommended. However, in some rare cases, continuous exposure to antivirals may promote the emergence of resistant viral strains, which can be difficult to manage. In the future, the introduction of new antiviral drugs, with differing modes of action compared to current medical therapy, could be an alternative until a truly effective preventive solution, such as a vaccine, is available.

Cell and Tissue Specific Metabolism of Nucleoside and Nucleotide Drugs: Case Studies and Implications for Precision Medicine

Many clinically used antiviral drugs are nucleoside or nucleotide analog drugs, which have a unique mechanism of action that requires intracellular phosphorylation. This dependence on intracellular activation presents novel challenges for the discovery and development of nucleoside/nucleotide analog drugs. Contrary to many small molecule drug development programs that rely on plasma pharmacokinetics and systemic exposures, the precise mechanisms that result in efficacious intracellular nucleoside triphosphate concentrations must be understood in the process of nucleoside/nucleotide drug development. The importance is highlighted here, using the following as case studies: the herpes treatment acyclovir, the cytomegalovirus therapy ganciclovir, and human immunodeficiency virus (HIV) treatments based on tenofovir, which are also in use for HIV prophylaxis. For each drug, the specificity of metabolism that results in its activation in different cells or tissues is discussed, and the implications explored. Acyclovir's dependence on a viral enzyme for activation provides selective pressure for resistance mutations. Ganciclovir is also dependent on a viral enzyme for activation, and suicide gene therapy capitalizes on that for a novel oncology treatment. The tissue of most relevance for tenofovir activation depends on its use as treatment or as prophylaxis, and the pharmacogenomics and drug-drug interactions in those tissues must be considered. Finally, differential metabolism of different tenofovir prodrugs and its effects on toxicity risk are explored. Taken together, these examples highlight the importance of understanding tissue specific metabolism for optimal use of nucleoside/nucleotide drugs in the clinic. SIGNIFICANCE STATEMENT: Nucleoside and nucleotide analogue drugs are cornerstones in current antiviral therapy and prevention efforts that require intracellular phosphorylation for activity. Understanding their cell and tissue specific metabolism enables their rational, precision use for maximum efficacy.

Herpes Simplex Virus and Varicella Zoster Virus Infections in Cancer Patients

Herpes simplex virus (HSV) and varicella zoster virus (VZV) are alpha herpesviruses that establish life-long latent infection in neuronal ganglia after primary infection. Periodic reactivation of these viruses results in recurrent infections that can have significant impact on patients' quality of life. HSV commonly causes oral and genital mucocutaneous infections whereas VZV is responsible for varicella/chickenpox and herpes zoster/shingles, but cancer patients are at particularly higher risk of complications including disseminated and visceral infections due to impaired cell-mediated immunity. While diagnosis of more common HSV and/or VZV infections is frequently clinically based, immunocompromised hosts may have atypical skin presentation or visceral involvement. Thus, diagnostic confirmation using virus-specific tests such as polymerase chain reaction or immunohistochemical staining is crucial in some cases. Oral acyclovir, valacyclovir and famciclovir are usually used for mild to moderate infections and intravenous acyclovir is the drug of choice for severe or disseminated infections. Foscarnet can be used when acyclovir-resistance is confirmed or suspected. Pharmaceutical prophylaxis against HSV and/or VZV should be considered in high-risk cancers patients. Currently, there is no commercially available vaccine against HSV, but VZV vaccines are available to prevent varicella and zoster.

An Insight into Current Treatment Strategies, Their Limitations, and Ongoing Developments in Vaccine Technologies against Herpes Simplex Infections

Herpes simplex virus (HSV) infection, the most prevalent viral infection that typically lasts for a lifetime, is associated with frequent outbreaks of oral and genital lesions. Oral herpes infection is mainly associated with HSV-1 through oral contact, while genital herpes originates due to HSV-2 and is categorized under sexually transmitted diseases. Immunocompromised patients and children are more prone to HSV infection. Over the years, various attempts have been made to find potential targets for the prevention of HSV infection. Despite the global distress caused by HSV infections, there are no licensed prophylactic and therapeutic vaccines available on the market against HSV. Nevertheless, there are numerous promising candidates in the pre-clinical and clinical stages of study. The present review gives an overview of two herpes viruses, their history, and life cycle, and different treatments adopted presently against HSV infections and their associated limitations. Majorly, the review covers the recent investigations being carried out globally regarding various vaccine strategies against oral and genital herpes virus infections, together with the recent and advanced nanotechnological approaches for vaccine development. Consequently, it gives an insight to researchers as well as people from the health sector about the challenges and upcoming solutions associated with treatment and vaccine development against HSV infections.

Acute retinal necrosis: pathophysiological aspects, diagnosis, and treatment

Acute retinal necrosis (ARN) is a devastating viral infection commonly associated with varicella zoster virus (VZV) and herpes simplex virus types 1 and 2 (HSV-1, HSV-2). Typically, ARN affects individuals without immune status disorders between the ages of 50-70. In two-thirds of the cases, one-eye involvement is observed and the inflammation can be presented as panuveitis. The most characteristic clinical manifestations are vitreitis, occlusion of the retinal arterioles, and peripheral necrotizing retinitis. Retinitis presents with the appearance of deep, multifocal, yellowish-white foci, typically localized in the peripheral retina. Systemic antivirals are the first treatment of choice for ARN. The goal of the therapy is to stop the viral replication and disease progression in the affected eye, as well as to prevent involvement of the healthy eye. The other eye can be attacked in an interval of 5 days to 30 years. The visual prognosis after illness is poor. Early diagnosis and timely initiation of treatment play an important role in maintaining visual acuity and preventing the other eye from being affected.

Discovery, Chemistry, and Preclinical Development of Pritelivir, a Novel Treatment Option for Acyclovir-Resistant Herpes Simplex Virus Infections

When the nucleoside analogue acyclovir was introduced in the early 1980s, it presented a game-changing treatment modality for herpes simplex virus infections. Since then, work has been ongoing to improve the weaknesses that have now been identified: a narrow time window for therapeutic success, resistance in immunocompromised patients, little influence on frequency of recurrences, relatively fast elimination, and poor bioavailability. The present Drug Annotation focuses on the helicase–primase inhibitor pritelivir currently in development for the treatment of acyclovir-resistant HSV infections and describes how a change of the molecular target (from viral DNA polymerase to the HSV helicase–primase complex) afforded improvement of the shortcomings of nucleoside analogs. Details are presented for the discovery process leading to the final drug candidate, the pivotal preclinical studies on mechanism of action and efficacy, and on how ongoing clinical research has been able to translate preclinical promises into clinical use.

Lack of an Effect of Polysorbate 80 on Intestinal Drug Permeability in Humans

PURPOSE

Despite no broad, direct evidence in humans, there is a potential concern that surfactants alter active or passive drug intestinal permeation to modulate oral drug absorption. The purpose of this study was to investigate the impact of the surfactant polysorbate 80 on active and passive intestinal drug absorption in humans.

METHODS

The human (n = 12) pharmacokinetics (PK) of three probe substrates of intestinal absorption, valacyclovir, chenodeoxycholic acid (CDCA), and enalaprilat, were assessed. Endogenous bile acid levels were assessed as a secondary measure of transporter and microbiota impact.

RESULTS

Polysorbate 80 did not inhibit peptide transporter 1 (PepT1)- or apical sodium bile acid transporter (ASBT)-mediated PK of valacyclovir and CDCA, respectively. Polysorbate 80 did not increase enalaprilat absorption. Modest increases in unconjugated secondary bile acid C_max ratios suggest a potential alteration of the in vivo intestinal microbiota by polysorbate 80.

CONCLUSIONS

Polysorbate 80 did not alter intestinal membrane fluidity or cause intestinal membrane disruption. This finding supports regulatory relief of excipient restrictions for Biopharmaceutics Classification System-based biowaivers.

[A Pharmacist's Query Avoiding Exacerbation of Adverse Effects in a Patient with Acyclovir Encephalopathy: A Case Report]

We report a haemodialysis patient with end-stage renal failure whom a pharmacist aided in the management of acyclovir (ACV) encephalopathy, which may have been related to valacyclovir hydrochloride (VACV) administered without sufficient dose reduction. The patient 78 years was admitted with a tentative diagnosis of varicella zoster viral meningitis. A pharmacist suspected ACV encephalopathy related to excessive VACV administration and raised a query with the attending physician. According to the pharmacist's proposal, ACV administration was discontinued and continuous hemodiafiltration (CHDF) was performed. On day 5 of hospitalisation, the consciousness disorder was improved. In this report, we showed the detailed CHDF conditions of the present case, and the contribution of a pharmacist to treating and avoiding ACV encephalopathy was discussed.

Efficacy and Safety of Antiviral Agents in Preventing Allograft Rejection Following CMV Prophylaxis in High-Risk Kidney Transplantation: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Many antiviral agents have been studied in clinical trials for allograft rejection prevention following cytomegalovirus (CMV) prophylaxis in high-risk kidney transplant patients. However, data on the most effective and safest treatment are lacking. We conducted a systematic review and network meta-analysis to rank CMV prophylaxis agents for allograft rejection prevention following CMV prophylaxis in high-risk kidney transplant patients according to their efficacy and safety. We conducted searches on the MEDLINE, Embase, SCOPUS, and CENTRAL databases, as well as the reference lists of selected studies up to December 2021, for published and peer-reviewed randomized controlled trials assessing the efficacy of CMV prophylaxis agents in high-risk kidney transplant patients. Thirteen studies were independently selected by three reviewers and included post-kidney transplant patients indicated for CMV prophylaxis who had been randomized to receive prophylactic antiviral agents or standard of care. The reviewers independently extracted data from the included studies, and direct and network meta-analyses were applied to assess the study outcomes. The probability of efficacy and safety was evaluated, and the drugs were assigned a numerical ranking. We evaluated the risk of bias using the Cochrane Risk of Bias 2.0 tool. The primary outcome was an incidence of biopsy-proven acute rejection, whereas the secondary outcome was a composite of major adverse drug reactions. Each outcome referred to the definition provided in the original studies. Valganciclovir, valacyclovir, and ganciclovir were identified to significantly decrease the incidence of biopsy-proven acute rejection with pooled risk differences (RDs) of −20.53% (95% confidence interval [CI] = −36.09% to −4.98%), −19.3% (95% CI = −32.7% to −5.93%), and −10.4% (95% CI = −19.7% to −0.12%), respectively. The overall major adverse drug reaction was 5.7% without a significant difference when compared with placebo. Valganciclovir had the best combined efficacy and safety among the examined antiviral agents and was the most effective and safest antiviral agent overall for allograft rejection prevention following CMV prophylaxis. Valacyclovir was the optimal alternative antiviral agent for patients who were unable to tolerate intravenous ganciclovir or access oral valganciclovir as financial problem. However, compliance and dose-related toxicities should be closely monitored.

Long-Term Follow-Up Results of a Patient Undergoing Acute Retinal Necrosis: A Case Report and Literature Review

Purpose

To describe the follow-up and treatment approach of a patient with acute retinal necrosis. Case Report. A 44-year-old male patient, who had complaints of pain in the right eye and blurred vision, was referred to our clinic. Best-corrected visual acuity (BCVA) was 0.4. There was 2+ anterior chamber reaction and diffuse smooth-rounded keratic precipitates. Fundus examination revealed optic nerve and vascular involvement. Fundus fluorescein angiography revealed extensive ischemia in the periphery. Oral antiviral therapy was preferred. In addition, systemic steroid and laser photocoagulation were applied. Nonetheless, retinal detachment developed 2 months later. Detachment, silicon removal, and cataract surgery were performed sequentially. It was observed that the patient was followed for 4.5 years and did not have contralateral eye involvement. Best-corrected visual acuity remained stable at 0.3.

Conclusion

Early diagnosis, appropriate treatment, accurate complication management, and frequent follow-up may provide useful vision in patients with acute retinal necrosis.

Geminal Diheteroatomic Motifs: Some Applications of Acetals, Ketals, and Their Sulfur and Nitrogen Homologues in Medicinal Chemistry and Drug Design

Acetals and ketals and their nitrogen and sulfur homologues are often considered to be unconventional and potentially problematic scaffolding elements or pharmacophores for the design of orally bioavailable drugs. This opinion is largely a function of the perception that such motifs might be chemically unstable under the acidic conditions of the stomach and upper gastrointestinal tract. However, even simple acetals and ketals, including acyclic molecules, can be sufficiently robust under acidic conditions to be fashioned into orally bioavailable drugs, and these structural elements are embedded in many effective therapeutic agents. The chemical stability of molecules incorporating geminal diheteroatomic motifs can be modulated by physicochemical design principles that include the judicious deployment of proximal electron-withdrawing substituents and conformational restriction. In this Perspective, we exemplify geminal diheteroatomic motifs that have been utilized in the discovery of orally bioavailable drugs or drug candidates against the backdrop of understanding their potential for chemical lability.

Role of Intravenous Acyclovir in Treatment of Herpes Simplex Virus Stromal Keratitis with Ulceration: A Review of 2 Cases

BACKGROUND Herpes simplex virus (HSV) stromal keratitis with ulceration is one of the most serious forms of herpes corneal infection and is one of the most difficult conditions in terms of clinical management. We assessed the efficacy of intravenous acyclovir in the treatment of this condition. CASE REPORT Two cases of HSV stromal keratitis with ulceration were reported in terms of clinical presentation, investigation, treatment, and outcome.Diagnosis was confirmed by polymerase chain reaction (PCR) analysis. PCR testing of corneal scraping samples identified HSV-1 in the first patient and HSV-2 in the second patient. The first patient initially presented with herpes geographic epithelial keratitis and progressed to HSV stromal keratitis with ulceration during treatment with a prophylactic dose of oral acyclovir. Despite oral acyclovir therapy, the cornea lesion continued to worsen. The treatment was switched to intravenous acyclovir. The stromal infiltration gradually improved, and the epithelial defect closed. The second patient, who had undergone penetrating keratoplasty for 13 years, presented with extensive corneal infiltration and corneal melting. The laboratory work-up was positive for HSV-2, and intravenous acyclovir was prescribed. The patient's corneal infiltration improved, but a persistent epithelial defect was present. Then, 100% autologous serum was used until the epithelial defect closed. Prophylactic treatment with oral acyclovir was prescribed to both patients to prevent disease recurrence. CONCLUSIONS Intravenous acyclovir might be considered as an alternative treatment for patients with HSV stromal keratitis with ulceration who do not respond to oral acyclovir or those with an extensive infection on a corneal graft.

Oral delivery of peptide therapeutics in infants: Challenges and opportunities

The vast majority of drugs are not designed or developed for pediatric and infant populations. Peptide drugs, which have become increasingly relevant in the past several decades, are no exception. Unfortunately, nearly all of the 60+ approved peptide drugs are formulated for injection, a particularly unfriendly mode of administration for infants. Although three peptide drugs were recently approved for oral formulations, this major advance in peptide drug delivery is available only for adults. In this review, we consider the current challenges and opportunities for the oral formulation of peptide therapeutics, specifically for infant populations. We describe the strategies that enable oral protein delivery and the potential impact of infant physiology on those strategies. We also detail the limited but encouraging progress towards 1) adapting conventional drug development and delivery approaches to infants and 2) designing novel infant-centric formulations. Together, these efforts underscore the feasibility of oral peptide delivery in infants and provide motivation to increase attention paid to this underserved area of drug delivery and formulation.

The evolution of nucleosidic analogues: self-assembly of prodrugs into nanoparticles for cancer drug delivery

Nucleoside and nucleotide analogs are essential tools in our limited arsenal in the fight against cancer. However, these structures face severe drawbacks such as rapid plasma degradation or hydrophilicity, limiting their clinical application. Here, different aspects of nucleoside and nucleotide analogs have been exposed, while providing their shortcomings. Aiming to improve their fate in the body and combating their drawbacks, two different approaches have been discussed, the prodrug and nanocarrier technologies. Finally, a novel approach called "PUFAylation" based on both the prodrug and nanocarrier technologies has been introduced, promising to be the supreme method to create a novel nucleoside or nucleotide analog based formulation, with enhanced efficacy and highly reduced toxicity.

A review: Mechanism of action of antiviral drugs

Antiviral drugs are a class of medicines particularly used for the treatment of viral infections. Drugs that combat viral infections are called antiviral drugs. Viruses are among the major pathogenic agents that cause number of serious diseases in humans, animals and plants. Viruses cause many diseases in humans, from self resolving diseases to acute fatal diseases. Developing strategies for the antiviral drugs are focused on two different approaches: Targeting the viruses themselves or the host cell factors. Antiviral drugs that directly target the viruses include the inhibitors of virus attachment, inhibitors of virus entry, uncoating inhibitors, polymerase inhibitors, protease inhibitors, inhibitors of nucleoside and nucleotide reverse transcriptase and the inhibitors of integrase. The inhibitors of protease (ritonavir, atazanavir and darunavir), viral DNA polymerase (acyclovir, tenofovir, valganciclovir and valacyclovir) and of integrase (raltegravir) are listed among the Top 200 Drugs by sales during 2010s. Still no effective antiviral drugs are available for many viral infections. Though, there are a couple of drugs for herpesviruses, many for influenza and some new antiviral drugs for treating hepatitis C infection and HIV. Action mechanism of antiviral drugs consists of its transformation to triphosphate following the viral DNA synthesis inhibition. An analysis of the action mechanism of known antiviral drugs concluded that they can increase the cell’s resistance to a virus (interferons), suppress the virus adsorption in the cell or its diffusion into the cell and its deproteinisation process in the cell (amantadine) along with antimetabolites that causes the inhibition of nucleic acids synthesis. This review will address currently used antiviral drugs, mechanism of action and antiviral agents reported against COVID-19.

Quercetin-Amino Acid Conjugates are Promising Anti-Cancer Agents in Drug Discovery Projects

Quercetin is a plant flavonoid with great potential for the prevention and treatment of disease. Despite the curative application of quercetin is hampered by low bioavailability, its core serves as a scaffold for generating more potent compounds with amplified therapeutic window. This review aims to describe recent advances in the improvement of the pharmacokinetic profile of quercetin via the amino acid prodrug approach which offers wide structural diversity, physicochemical and biological properties improvement. According to the findings, conjugation of quercetin with amino acids results in increased solubility, stability, cellular permeability as well as biological activity. In particular quercetin- amino acid conjugates exhibited potent anticancer, MDR-reversal and antibiotic resistance reversal activities. The synthetic pathways and examples of quercetin-amino acid conjugates are considered. Practical considerations and challenges associated with the development of these prodrugs are also discussed. This mini-review covers the literature on quercetin-amino acid conjugates since 2001 when the first thematic work was published.

Management Strategies of Acute Retinal Necrosis: Current Perspectives

Acute retinal necrosis is a rare yet devastating disease, with significant ocular morbidity. Over the past several decades, initial treatment regimens have shifted from intravenous antivirals requiring hospital admission to the routine use of oral antivirals with intravitreal antivirals for immediate local control. Given the rarity of this disease process and a lack of large-scale research trials, debate continues over recommended practice guidelines. In this paper, we review current diagnostic criteria and recommend a treatment algorithm based on available evidence.

Updates in bile acid-bioactive molecule conjugates and their applications

Bile acid conjugates are emerging as important chemical resources due to their low cost and wide availability of bile acids, making them privileged molecules in drug carrier systems and building blocks for derivatization and chiral template introduction into bioactive molecules. In recent years, bile acids as scaffolds in supramolecular, medicinal, and material chemistry attracted prime focus of researchers as an area of research to be followed with passion. Due to peculiar physicochemical and biological properties, bile acid exhibited various applications in biomedical and pharmaceutical fields. In this review, the bile acid conjugations with different bioactive compounds have been discussed to understand their influence on the bioavailability of bioactive compounds.

Viral Loads in Ocular Fluids of Acute Retinal Necrosis Eyes Infected by Varicella-Zoster Virus Treated with Intravenous Acyclovir Treatment

Acute retinal necrosis (ARN) is a rare viral endophthalmitis, and human herpesvirus is the principal pathogen. Early diagnosis and treatment are critical to avoid visual impairment by ARN, and pars plana vitrectomy (PPV) is required in advanced cases. In this study, we evaluated the transition of viral load in ocular fluids of ARN eyes with varicella-zoster virus (VZV) after intravenous acyclovir treatment. Fourteen eyes of 13 patients were analyzed retrospectively. All patients received intravenous acyclovir treatment, and eventually, all eyes underwent PPV. A polymerase chain reaction (PCR) test showed a 100% detection rate in all aqueous humor samples collected before the treatment (Pre-AH), as well as aqueous humor (Post-AH) and vitreous fluid samples (VF), collected during PPV conducted after the treatment. Within eight days or less of acyclovir treatment, viral loads both in AH and VF did not decrease significantly. Furthermore, the viral load of Pre-AH had a strong correlation with that of VH. These data suggest that in ARN eyes with VZV infection, the AH sample for the PCR test was reliable to confirm the pathogen. We propose that short-term treatment of intravenous acyclovir may be insufficient for reducing intraocular viral load, and the Pre-AH sample could be a predictor of viral activity in the eyes after acyclovir treatment.

Modifications on the heterocyclic base of ganciclovir, penciclovir, acyclovir - syntheses and antiviral properties

АBSTRACTEsters of the antiherpetic drugs ganciclovir, penciclovir with the bile acids (cholic, chenodeoxycholic and deoxycholic) and amino acid esters of acyclovir were generated and evaluated for their in vitro antiviral activity against herpes simplex viruses type 1 and type 2 (HSV-1, HSV-2). The antiviral assays demonstrated that modified analogs of ACV and PCV are less active compared to the initial substances against HSV-1and HSV-2. CC50 for ganciclovir-deoxycholate corresponded to the CC50 of the other analogs and its activity is lower than ganciclovir. Obtained results show that tested modification do not improve bioavailability of nucleoside analogs in cells.

In silico, in ovo and in vitro antiviral efficacy of phosphorylated derivatives of abacavir: an experimental approach

Outstanding increase of oral absorption, bioavailability, and antiviral efficacy of phosphorylated nucleosides and basic antiviral influence of abacavir is the central idea for the development of new series of phosphorylated abacavir (ABC) derivatives. The designed compounds were primarily screened for antiviral nature against HN protein of NDV and VP7 protein of BTV using the molecular environment approach. Out of all the designed compounds, the compounds which are having higher binding energies against these two viral strains were prompted for the synthesis of the target compounds (5A-K). Among the synthesized title compounds (5A-K), the compounds which have exhibited higher dock scores akin to the rest of the compounds were then selected and screened for the antiviral activity against NDV and BTV infected embryonated eggs and BHK 21 cell lines through the in ovo and in vitro approaches. The results revealed that all the designed compounds have formed higher binding energies against both the targets. Among all, the compounds which are selected based on their dock scores such as 5A, 5F, 5G, 5H, 5I, and 5K against NDV and 5J, 5E, 5I, 5C, 5A, and 5K against BTV have shown significant antiviral activity against HN protein of NDV, VP7 protein of Bluetongue virus in both NDV- and BTV-treated embryonated eggs and BHK 21 cell lines. Hence, it is concluded that, the best lead compounds will stand as the potential antiviral agents and prompted them as virtuous therapeutics against NDV and BTV in future.

Racemisation in Chemistry and Biology

The two enantiomers of a compound often have profoundly different biological properties and thus their liability to racemisation in aqueous solutions is an important piece of information. The authors reviewed the available data concerning the process of racemisation in vivo, in the presence of biological molecules (e.g., racemase enzymes, serum albumin, cofactors and derivatives) and under purely chemical but aqueous conditions (acid, base and other aqueous systems). Mechanistic studies are described critically in light of reported kinetic data. The types of experimental measurement that can be used to effectively determine rate constants of racemisation in various conditions are discussed and the data they provide is summarised. The proposed origins of enzymatic racemisation are presented and suggest ways to promote the process that are different from processes taking place in bulk water. Experimental and computational studies that provide understanding and quantitative predictions of racemisation risk are also presented.

Current Antivirals and Novel Botanical Molecules Interfering With Herpes Simplex Virus Infection

Herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent within the human population and are characterized by lifelong infections and sporadic recurrences due to latent neuron infection. Upon reactivations, HSVs may manifest either, symptomatically or asymptomatically and be shed onto others through mucosae body fluids. Although, HSVs can produce severe disease in humans, such as life-threatening encephalitis and blindness, the most common symptoms are skin and mucosal lesions in the oro-facial and the genital areas. Nucleoside analogs with antiviral activity can prevent severe HSV infection, yet they are not very effective for treating skin manifestations produced by these viruses, as they only reduce in a few days at most the duration of lesions. Additionally, HSV variants that are resistant to these antivirals may arise, especially in immunosuppressed individuals. Thus, new antivirals that can reduce the severity and duration of these cutaneous manifestations would certainly be welcome. Here, we review currently available anti-herpetic therapies, novel molecules being assessed in clinical trials and new botanical compounds reported in the last 20 years with antiviral activities against HSVs that might represent future treatments against these viruses.

Post liver transplant recurrent and de novo viral infections

Survival following liver transplantation has changed dramatically owing to improvement in surgical techniques, peri-operative care and optimal immunosuppressive therapy. Post-Liver transplant (LT) de novo or recurrent viral infection continues to cause major allograft dysfunction, leading to poor graft and patient survival in untreated patients. Availability of highly effective antiviral drugs has significantly improved post-LT survival. Patients transplanted for chronic hepatitis B infection should receive life-long nucleos(t)ide analogues, with or without HBIg for effective viral control. Patients with chronic hepatitis C should be commenced on directly acting antiviral (DAA) drugs prior to transplantation. DAA therapy for post-LT recurrent hepatitis C infection is associated with close to 100% sustained virological response (SVR), irrespective of genotype. De novo chronic Hepatitis E infection is an increasingly recognised cause of allograft dysfunction in LT recipients. Untreated chronic HEV infection of the graft may lead to liver fibrosis and allograft failure. CMV and EBV can reactivate leading to systemic illness following liver transplantation. With COVID-19 pandemic, post-transplant patients are at risk of SARS-Co-V2 infection. Majority of the LT recipients require hospitalization, and the mortality in this population is around 20%. Early recognition of allograft dysfunction and identification of viral aetiology is essential in the management of post-LT de novo or recurrent infections. Optimising immunosuppression is an important step in reducing the severity of allograft damage in the treatment of post-transplant viral infections. Viral clearance or control can be achieved by early initiation of high potency antiviral therapy.

[Acyclovir encephalopathy in a peritoneal dialysis patient despite adjusting the dose of oral acyclovir: a case report]

We report a case of acyclovir encephalopathy in a 77-year-old man who was introduced to peritoneal dialysis three years earlier. He developed herpes zoster and was treated with acyclovir (ACV) at 800 mg daily per oral. Two days later, he developed consciousness disturbance, hallucinations and asterixis. Acyclovir was stopped and continuous ambulatory peritoneal dialysis (CAPD) was switched to hemodialysis, which resulted in the resolution of his symptoms. Because the optimal dose of ACV varies among individuals depending on the bioavailability of ACV and metabolic enzyme activity, ACV encephalopathy can occur even when the acyclovir dose is modified according to the renal function of the affected patient. Because CAPD provides a poorer ACV clearance than hemodialysis, CAPD patients tend to have a higher risk of developing ACV encephalopathy and to recover more slowly. If CAPD patients develop ACV encephalopathy, a temporary change in the type of dialysis to hemodialysis should be considered.

Absorption, Distribution, Metabolism, and Excretion of the Novel Helicase-Primase Inhibitor, Amenamevir (ASP2151), in Rodents

BACKGROUND AND OBJECTIVES

The helicase-primase inhibitor amenamevir (ASP2151) is a novel therapeutic agent which has been approved for the treatment of herpes zoster. The present study examined the pharmacokinetic profile of amenamevir in rodents and compared it with data from the literature of past and current established therapies (acyclovir and valaciclovir) to provide additional data to facilitate drug discovery and proper drug use.

METHODS

In situ absorption, blood and plasma radioactivity concentrations, tissue distribution, and excretion were determined using liquid scintillation counting. Plasma amenamevir concentrations were measured using a validated chromatographic method. Chemical structures of in vivo metabolites were investigated using liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy.

RESULTS

Amenamevir, after single intravenous administration to mice, had an elimination half-life of 2 h. Bioavailability was 40% after single oral administration. In situ absorption data indicated that amenamevir is mainly absorbed in the small intestine. The main component in mouse plasma was amenamevir, accounting for 87.9% of amenamevir-derived components. Our results suggest that the main elimination pathway in mice is oxidative metabolism at a methyl group and a 1,2,3-trisubstituted benzene ring followed by biliary and fecal excretion. Following oral administration of ¹⁴C-amenamevir to mice, 100.63% of the dose (10.06% in urine and 90.46% in feces) was excreted by 96 h post-dose.

CONCLUSIONS

The underlying mechanism of the improved pharmacokinetic profile of amenamevir was linked to an improved absorption ratio (not hepatic availability) compared to acyclovir, and qualitative differences in elimination (slow metabolism of amenamevir vs rapid urinary excretion of acyclovir/valaciclovir).

Valacyclovir-induced Neurotoxicity in a Patient with a Preserved Renal Function

Valacyclovir, a prodrug of acyclovir, is the first-line treatment for herpes zoster, but the renal function must be monitored, because acyclovir is metabolized by the kidneys. We herein report a case of valacyclovir-induced neurotoxicity with no preceding renal impairment. An 88-year-old man was admitted because of an impaired consciousness after the administration of valacyclovir at 3,000 mg daily for herpes zoster on the chest. His consciousness level gradually improved with hydration and valacyclovir withdrawal. It was later confirmed that the level of acyclovir on admission had been 35.45 μg/mL in the blood and 36.45 μg/mL in the cerebrospinal fluid.

Application of a Refined Developability Classification System

In 2010, the Developability Classification System was proposed as an extension of the Biopharmaceutics Classification System to align the classification system with the need for early evaluation of drug candidates according to their developability as oral formulations. Recent work on the Developability Classification System has resulted in the refined developability classification system (rDCS), consisting of standard investigations to estimate drug candidate solubility and permeability and offering customized investigations that are triggered when there is a potential for supersaturation/precipitation (e.g., salts of acids, weak bases) or to investigate permeation versus dissolution-limited absorption. In the present study, the rDCS concept was successfully applied to 6 marketed compounds (aciclovir, albendazole, danazol, dantrolene, dipyridamole, and piroxicam), for which there is a rich database of information. Furthermore, the rDCS was applied to 20 pipeline compounds from past and current research projects at Bayer AG. The rDCS was able to predict the results in humans correctly in 80% of cases. Overall, the results suggest that the rDCS is a highly useful tool for estimating the in vivo behavior of new drug candidates.

[Diagnostic and therapeutic recommendations for sexually transmitted diseases: Genital herpes]

TREATMENT OF THE INITIAL INFECTION OR FIRST CLINICAL EPISODE OF GENITAL HERPES: An initial infection or first clinical episode of genital herpes is treated with oral aciclovir 200mg×5/d for 5 to 10 days depending on clinical status. The recommended dosage for valaciclovir is 1g×2/d and treatment duration is identical to that for aciclovir. TREATMENT OF HERPES RECURRING DURING PREGNANCY: There are no studies of the efficacy of antiviral therapy on the symptoms of genital recurring during pregnancy. However, initial anti-viral treatment using aciclovir or valaciclovir may be given where warranted by symptoms (i.e. duration and severity of symptoms). Valaciclovir may be used instead (equivalent efficacy but better safety data for aciclovir). Valaciclovir may be given at a dosage of 1×500mg b.i.d. p.o. for 5 days. PROPHYLACTIC ANTI-VIRAL TREATMENT DURING PREGNANCY: In female patients presenting an initial infection or infection recurring during pregnancy, although there is no demonstrated benefit for prophylactic treatment in reducing the risk of neonatal herpes, anti-viral prophylaxis is recommended after 36 WA (weeks' amenorrhoea) to limit the need for Caesarean section due to herpetic lesions. The recommended antivirals are aciclovir at a dosage of 400mg t.i.d p.o. or valaciclovir at a dosage of 500mg b.i.d. p.o. until delivery.

A physiologically based pharmacokinetic model for valacyclovir established based on absolute expression quantity of hPEPT1 and its application

In this study, a physiologically based pharmacokinetic (PBPK) model was established for valacyclovir based on absolute expression quantity of hPEPT1 along the entire length of the human intestine and other reliable in vitro, in vivo observed data. The PBPK model-3 defined acyclovir as metabolite of valacyclovir and simulated the plasma concentration-time profiles of valacyclovir and acyclovir simultaneously. It was validated strictly by a series of observed plasma concentration-time profiles. The average fold error (AFE) and absolute average fold error (AAFE) values were all smaller than 2. Then, it was used to quantitatively evaluate the effect of hPEPT1, luminal degradation rate, drug release rate and gastric residence time on the oral absorption of valacyclovir and acyclovir. The PBPK model-3 suggests that mainly 75% of valacyclovir was absorbed by active transport of hPEPT1. The luminal degradation of valacyclovir in the upper intestinal lumen cannot be considered the only reason for its incomplete bioavailability. The plasma concentration-time profiles of valacyclovir and its metabolite acyclovir were not sensitive to dissolution rate faster than T_85% = 120 min. Prolonged gastric residence time of sustained release tablet can improve the oral absorption of valacyclovir. All in all, the PBPK model-3 in this study is reliable and accurate. It is useful for the research of clinical application and dosage forms design of valacyclovir.

Amino Acids in the Development of Prodrugs

Although drugs currently used for the various types of diseases (e.g., antiparasitic, antiviral, antibacterial, etc.) are effective, they present several undesirable pharmacological and pharmaceutical properties. Most of the drugs have low bioavailability, lack of sensitivity, and do not target only the damaged cells, thus also affecting normal cells. Moreover, there is the risk of developing resistance against drugs upon chronic treatment. Consequently, their potential clinical applications might be limited and therefore, it is mandatory to find strategies that improve those properties of therapeutic agents. The development of prodrugs using amino acids as moieties has resulted in improvements in several properties, namely increased bioavailability, decreased toxicity of the parent drug, accurate delivery to target tissues or organs, and prevention of fast metabolism. Herein, we provide an overview of models currently in use of prodrug design with amino acids. Furthermore, we review the challenges related to the permeability of poorly absorbed drugs and transport and deliver on target organs.

Evaluating the intestinal and oral absorption of the prodrug valacyclovir in wildtype and huPepT1 transgenic mice

The purpose of this work was to evaluate the intestinal permeability, oral absorption and disposition of the ester prodrug valacyclovir in wildtype mice and a huPepT1 transgenic mouse model. PepT1 (SLC15A1) is a transporter apically expressed along the lumen of the gastrointestinal tract and is responsible for the absorption of di-/tripeptides, ACE inhibitors, β-lactam antibiotics and numerous prodrugs. Unfortunately, PepT1-mediated substrates that have been extensively studied were shown to exhibit species-dependent absorption and pharmacokinetics. Accordingly, in situ intestinal perfusion studies were conducted and valacyclovir uptake was shown to have a 30-fold lower K_m and 100-fold lower V_max in huPepT1 compared to wildtype mice. Moreover, inhibition studies demonstrated that the huPepT1 transporter alone was responsible for valacyclovir uptake, and segment-dependent studies reported significant reductions in permeability along the length of small intestine in huPepT1 mice. Subsequent oral administration studies revealed that the in vivo rate and extent of valacyclovir absorption were lower in huPepT1 mice, as indicated by 3-fold lower C_max and 3-fold higher T_max values, and an AUC_0-180 that was 80% of that observed in wildtype mice. However, no significant changes in drug disposition were observed between genotypes after intravenous bolus administration of acyclovir. Lastly, mass balance studies established that the bioavailability of acyclovir, after oral dosing of valacyclovir, was 77.5% in wildtype mice and 52.8% in huPepT1 mice, which corroborated values of 51.3% in clinical studies. Thus, it appears the huPepT1 transgenic mice may be a better model to study prodrug absorption and disposition in humans than wildtype mice.

Sodium caprate enables the blood pressure-lowering effect of Ile-Pro-Pro and Leu-Lys-Pro in spontaneously hypertensive rats by indirectly overcoming PepT1 inhibition

The tripeptides, Ile-Pro-Pro (IPP) and Leu-Lys-Pro (LKP), inhibit angiotensin-converting enzyme (ACE) resulting in lowered blood pressure. Our hypothesis was that the medium chain fatty acid permeation enhancer, sodium caprate (C₁₀), may prevent the decrease in permeability of the tripeptides when PepT1 is inhibited by glycyl-sarcosine (Gly-Sar), a situation that may occur in the presence of food hydrolysates. Using Caco-2 monolayers and isolated rat jejunal tissue, the apparent permeability coefficients (P_app) of [³H]-IPP and [³H]-LKP were assessed in the presence of Gly-Sar with and without C₁₀. Gly-Sar decreased the P_app of both tripeptides across monolayers and isolated jejunal tissue, but C₁₀ restored it. C₁₀ likely increased the paracellular permeability of the tripeptides, as indicated by immunofluorescence changes in tight junction proteins in Caco-2 monolayers accompanied by a concentration-dependent decrease in transepithelial electrical resistance (TEER). [³H]-IPP and [³H]-LKP were orally-gavaged to normal rats with Gly-Sar, C₁₀, or with a mixture. Plasma levels of both peptides were reduced by Gly-Sar to less than half that of the levels detected in its absence, but were restored when C₁₀ was co-administered. In spontaneously hypertensive rats (SHRs), unlabelled IPP and LKP lowered blood pressure when delivered either by i.v. or oral routes. Oral gavage of Gly-Sar reduced the hypotensive action of peptides in SHRs, but the effect was restored in the presence of C₁₀. In conclusion, there was a reduction in the hypotensive effects of IPP and LKP in SHRs when intestinal PepT1 was inhibited by Gly-Sar, but C₁₀ may circumvent this by enhancing paracellular permeability.

The evolution of nucleoside analogue antivirals: A review for chemists and non-chemists. Part 1: Early structural modifications to the nucleoside scaffold

This is the first of two invited articles reviewing the development of nucleoside-analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. Rather than providing a simple chronological account, we have examined and attempted to explain the thought processes, advances in synthetic chemistry and lessons learned from antiviral testing that led to a few molecules being moved forward to eventual approval for human therapies, while others were discarded. The present paper focuses on early, relatively simplistic changes made to the nucleoside scaffold, beginning with modifications of the nucleoside sugars of Ara-C and other arabinose-derived nucleoside analogues in the 1960's. A future paper will review more recent developments, focusing especially on more complex modifications, particularly those involving multiple changes to the nucleoside scaffold. We hope that these articles will help virologists and others outside the field of medicinal chemistry to understand why certain drugs were successfully developed, while the majority of candidate compounds encountered barriers due to low-yielding synthetic routes, toxicity or other problems that led to their abandonment.

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This is the first of two invited articles reviewing the development of nucleoside-analogue antiviral drugs.

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It is written for a target audience of virologists and other non-chemists, and for chemists unfamiliar with the field.

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Numerous modifications have been made to the nucleoside scaffold in order to impart therapeutic benefits.

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Nucleoside modifications led to the development of potent antivirals such as acyclovir, entecavir, and tenofovir.

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We examine thought processes, progress in synthetic chemistry and results of antiviral testing that led to approved drugs.

Sequential retinal necrosis secondary to varicella zoster in unrecognised long-standing HIV infection: patient safety report

A retired woman with left ophthalmic shingles of over 2 years’ duration attended with bilateral vision loss and systemic upset. Acute retinal necrosis with detachment was detected on right fundus examination. Cataract in left eye precluded funduscopy. Ocular ultrasonography revealed fibrotic retinal detachment in the left eye. MRI brain and orbits also showed signals of retinal detachment. No abnormal MRI signal within the optic nerve or brain was found. Varicella zoster virus was detected in ocular aqueous and blood samples. High-dose intravenous acyclovir was administered. HIV test was positive with a very low CD4 count. Antiretroviral medications were prescribed. There was no recovery of vision. She was certified as blind, and social services were involved in seeking to provide alterations to her home in view of her severe disability. This case highlights the importance of suspecting HIV in patients with severe or chronic ophthalmic shingles. Images and implications for clinical practice are presented.

[Acyclovir-resistant perineal HSV infection revealing chronic lymphoid leukaemia]

BACKGROUND

Chronic HSV infection is a cause of chronic perineal ulcerations. We report a case of a chronic and refractory HSV infection revealing chronic lymphoid leukaemia.

PATIENTS AND METHODS

An 85-year-old woman with an 8-month history of chronic perineal ulcerations was referred to our dermatology department. She had no previous medical history of herpes infection. Skin biopsies ruled out carcinoma but were consistent with HSV infection. A local swab was positive for HSV2. Treatment with valaciclovir and intravenous acyclovir (ACV) at the recommended doses was ineffective. Laboratory tests revealed type-B chronic lymphoid leukaemia. Molecular biology studies confirmed the presence of ACV-resistant HSV via decreased thymidine kinase activity (stop codon: M183stop). Foscarnet was administered for a period of 3 weeks with almost complete healing of the ulcerations. Treatment was stopped prematurely due to acute renal insufficiency and the remaining lesions were treated using imiquimod cream. Valaciclovir was prescribed to prevent further episodes. The condition recurred a mere 11 months later.

DISCUSSION

The prevalence of ACV-resistant HSV is 0.32 % in immunocompetent patients and 3.5 % in immunocompromised patients. Insufficient dosing regimens or prolonged treatment with TK inhibitors result in the local selection of pre-existing mutant HSV viruses. Foscarnet, a DNA polymerase inhibitor, is the treatment of choice in HSV-resistant infections. ACV-resistant HSV is less virulent and replicates less, with reactivations being mainly due to wild-type HSV latent in the neural ganglia. Valaciclovir can be used as a preventive treatment. To our knowledge, this is the first case of ACV-resistant HSV infection revealing chronic lymphoid leukaemia.

CONCLUSION

Chronic perineal ulcerations can be the first manifestation of immunodeficiency seen for example with haematological diseases. In the event of clinical resistance of an HSV infection to recommended thymidine kinase inhibitor regimens, the use of foscarnet should be considered.

[Management of pregnant women with first episode of genital herpes. Guidelines for clinical practice from the French college of gynecologists and obstetricians (CNGOF)]

OBJECTIVE

To provide guidelines for the management of first episode genital herpes during pregnancy and in the immediate postpartum period.

METHODS

MedLine and Cochrane Library databases search and review of the main foreign guidelines.

RESULTS

In case of first episode genital herpes during pregnancy, antiviral treatment with acyclovir (200mg 5 times daily) or valacyclovir (1000mg twice daily) for 5 to 10 days is recommended (grade C). The patient should be tested for HIV if not previously done (grade B). Daily suppressive antiviral treatment with acyclovir (400mg 3 times daily) or valacyclovir (500mg twice daily) is recommended from 36 weeks for women who have had a first episode genital herpes during pregnancy (grade B). A cesarean section should be performed in case of suspicion of first episode genital herpes at the onset of labor (grade B) or premature rupture of the membranes at term (professional consensus), or in case of first episode genital herpes less than 6 weeks before delivery (professional consensus). In the event of first episode genital herpes highlighted in the postpartum period, the neonatologist should be informed (professional consensus). The patient may be treated according the scheme described above.

CONCLUSION

A cesarean section should be performed in case of first episode genital herpes less than 6 weeks before delivery.

Amino acid and peptide prodrugs of diphenylpropanones positive allosteric modulators of α7 nicotinic receptors with analgesic activity

α7 Nicotinic acetylcholine receptors (nAChRs) are ion channels implicated in a number of CNS pathological processes, including pain and psychiatric, cognitive and inflammatory diseases. Comparing with orthosteric agonism, positive allosteric modulation of these channels constitutes an interesting approach to achieve selectivity versus other nicotinic receptors. We have recently described new chalcones and 1,3-diphenylpropanones as positive allosteric modulators (PAMs) of α7 nAChRs, which proved to have good analgesic activities but poor pharmacokinetic properties. Here we report the preparation of amino acid and peptide derivatives as prodrugs of these modulators with the aim of improving their in vivo biological activity. While the valine derivative showed very short half life in aqueous solutions to be considered a prodrug, Val-Val and Val-Pro-Val are suitable precursors of the parent 1,3-diphenylpropanones, via chemical and enzymatic transformation, respectively. Compounds 19 (Val-Val) and 21 (Val-Pro-Val), prodrugs of the 2',5',4-trihydroxy-1,3-diphenylpropan-1-one 3, showed significant antinociceptive activity in in vivo assays. The best compound, 21, displayed a better profile in the analgesia test than its parent compound 3, exhibiting about the same potency but long-lasting effects.

Incorporation of a Biguanide Scaffold Enhances Drug Uptake by Organic Cation Transporters 1 and 2

Membrane transporters play a significant role in the transport of many endogenous and exogenous compounds. The knowledge of transporter substrate requirements has allowed further development of drugs that utilize them to ensure tissue permeation. In this study, we demonstrate that inclusion of a biguanide functionality can potentiate uptake by the organic cation transporters 1 and 2 (OCT1 and OCT2). We synthesized 18 pairs of structurally diverse compounds, each pair consisting of a parent amino compound and its biguanide analog; and then assessed their cellular uptake in HEK293 cells overexpressing human OCT1 or OCT2. Our results show that addition of the biguanide significantly improved OCT1- and OCT2-mediated transport for the majority of compounds. The biguanides also inhibited the uptake of prototypical substrates of both transporters, 1-methyl-4-phenylpyridinium (MPP+) and metformin. We found that molecular weight, molecular volume, Log D (pH 7.4), and accessible surface area were important determinants of OCT2 substrates, but none of these parameters was a significant factor for OCT1. More so, the inhibition of MPP+ uptake correlated linearly with that of metformin uptake for the tested biguanides in both cell lines. Taken together, we conclude that the inclusion of the biguanide scaffold in nonsubstrates of OCT1 and OCT2 increase their propensity to become substrates and inhibitors for these transporters.

Recurrent Body Rash Warranted Second Desensitization With Acyclovir in a Myeloma Patient: A Case Report

A 75-year-old woman developed a moderately severe rash about a week and a half after the start of bortezomib (Btb)-based chemotherapy for IgG lambda multiple myeloma; at the time, she was also receiving acyclovir as antiviral prophylaxis in addition to herpes zoster (HZ) vaccination. HZ reactivation rate is high in Btb recipients; therefore, the timing of antiviral prevention is critical in relation to Btb. Attempts were made to identify the offending agent based on the timing of drugs administered and the appearance of skin lesions in relation to other drugs. Both Btb and acyclovir were potential culprits. However, the timing of rash presented on days 9 - 10 revealed the offending agent when the corticosteroid was weaned off while acyclovir continued. A decision was made to administer acyclovir rapid desensitization program (RDP) for our patient.

Fundamentals of Clinical Pharmacology With Application for Pregnant Women

Medication use is common in pregnancy, yet for most medications the optimal formulation and dosage have not been described specifically for pregnant women. Often, adverse effects are only discovered anecdotally or after extensive off-label use occurs. Since pharmacologic research that includes pregnant women is sparse and animal studies are often not applicable to the human fetus, providers must use knowledge of drug behavior and normal physiologic changes of pregnancy to personalize treatment for pregnant women. In this review, we present an overview of the basic concepts of clinical pharmacology: pharmacokinetics, pharmacodynamics, and pharmacogenomics. The normal physiologic changes of pregnancy are presented as a framework to understand alterations in drug behavior. A clinical vignette that addresses 4 pregnancy scenarios involving medications-preterm birth, vaccination, herpes simplex virus infection, and codeine toxicity-is provided to illustrate application of core clinical pharmacologic concepts. Discussion of relevant literature illustrates the challenges of offering individualized pharmacologic therapy in pregnancy.