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1.
Am J Pharm Educ ; 87(11): 100543, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37331515

RESUMO

OBJECTIVE: To determine how underrepresented minority (URM) student pharmacists' intersectionality affects professional identity formation early in their academic career. METHODS: A qualitative study was undertaken. All students from Classes 2022 through 2025 at Texas A&M University School of Pharmacy were required to engage in reflection on a personal statement of philosophy of practice early in their first year of pharmacy as part of the structured longitudinal co-curricular course requirement. Statements of the URM students who referenced their intersecting identities were selected for deductive analysis per Bingham and Witkowsky and inductive analysis using Lincoln and Guba's approach to content analysis. RESULTS: Of the 221 URM student pharmacists within the 4 cohorts who submitted a statement, 38 statements (92% Hispanic students) met the inclusion criteria. Student hometowns and the identity domains of the individual, relational, and collective were selected a priori for the deductive analysis. Students most often referenced individual identity characteristics that fit under the Principles I, IV, V, and VII of the Code of Ethics for Pharmacists. Three themes emerged from the inductive analysis: (1) defining experiences and resulting realizations, (2) motivating forces, and (3) aspirations as a pharmacist. A working hypothesis was developed. CONCLUSION: The URM students' intersecting identities (race, ethnicity, socioeconomic class, and belonging to an underserved community) influenced their early professional identity formation. The desire to bring about racial uplift was observed among the Hispanic students as early in their P1 year through the School's required co-curricular reflection. Such reflective practice serves as an effective vehicle for the students to recognize their intersecting identities that impact their professional identity.


Assuntos
Educação em Farmácia , Estudantes de Medicina , Humanos , Identificação Social , Farmacêuticos , Enquadramento Interseccional
2.
Am J Pharm Educ ; 87(3): ajpe8864, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36220176

RESUMO

Objective. To study how a debate format could be a helpful tool to enhance group functionality and decision-making in schools of pharmacy.Methods. This study examines the potential of a debate format to facilitate discussion and shift viewpoints. Changes in viewpoint and feedback from the Academic Leadership Fellows Program (ALFP) Cohort 16 debates at the February 2020 American Association of Colleges of Pharmacy (AACP) Interim Meeting generated two data sets for each discussion topic to analyze debate effectiveness. Pre- and post-debate audience viewpoints were compared to determine the extent to which debates influenced viewpoints. Continuing pharmacy education (CPE) evaluations of the debate learning objectives provided information on participants' views of the debate format.Results. The debate format appeared to shift opinions on all three topics discussed. In addition, audience members responded in agreement or strong agreement that the debate format was of benefit to both leadership interactions and team environments.Discussion. While group functionality is an important aspect of effective decision-making, it is not always considered in pharmacy school operations. Incorporating debate components could improve the quality of group functionality, thereby positively impacting decision-making in schools of pharmacy.


Assuntos
Educação em Farmácia , Assistência Farmacêutica , Farmácia , Estudantes de Farmácia , Humanos , Estados Unidos , Educação em Farmácia/métodos , Faculdades de Farmácia , Docentes de Farmácia
3.
Am J Pharm Educ ; 87(3): ajpe8918, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36202422

RESUMO

Objective. To describe the landscape of well-being content inclusion across schools and colleges of pharmacy in the United States and Canada through identification of content implementation, incorporation, and assessment.Methods. A cross-sectional survey was distributed to all accredited schools and colleges of pharmacy in the United States (n=143) and Canada (n=10). Survey questions included curricular and cocurricular timing, frequency, assessment strategies, and support for well-being initiatives, using a framework of eight dimensions (pillars) of wellness to categorize content.Results. Descriptive data analyses were applied to 99 completed surveys (65%), 89 (62%) in the United States and 10 (100%) in Canada. Well-being content was most prevalent within the cocurricular realm and incorporated into didactic and elective more than experiential curricula. The most content came from intellectual, emotional, and physical pillars, and the least content came from financial, spiritual, and environmental pillars. Less than 50% of schools and colleges of pharmacy include well-being within their strategic plans or core values. Funding is primarily at the level of the university (59%) or the school or college of pharmacy (59%). Almost half of respondents reported inclusion of some assessment, with a need for more training, expertise, and standardization.Conclusion. Survey results revealed a wide range of implementation and assessment of well-being programs across the United States and Canada. These results provide a reference point for the state of well-being programs that can serve as a call to action and research across the Academy.


Assuntos
Educação em Farmácia , Estudantes de Farmácia , Humanos , Estados Unidos , Educação em Farmácia/métodos , Estudos Transversais , Faculdades de Farmácia , Currículo , Inquéritos e Questionários , Canadá
4.
Am J Pharm Educ ; 86(6): 8773, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-34697019

RESUMO

Given the limited availability of conventional pharmacy positions, pharmacy programs face a challenge in ensuring that all graduates obtain jobs that fulfill their goals and ambitions. Thus, it is imperative to explore and discuss unconventional but promising positions, specifically regarding their availability and needs. In exploring these positions, it is important to recognize technical and nontechnical skill sets that pharmacy graduates possess at graduation, identify unique pathways to help students explore job alternatives, and educate faculty and students about employment opportunities beyond the traditional setting if desired or necessary. Students must become aware of the opportunities that exist in both conventional (pharmacist clinician) and unconventional (pharmacist innovator) pharmacy careers and be able to articulate the translational skills from their training. Pharmacy programs and faculty can better support students by fostering the development and marketing of their skills.


Assuntos
Educação de Pós-Graduação em Farmácia , Educação em Farmácia , Farmácia , Estudantes de Farmácia , Escolha da Profissão , Humanos , Recursos Humanos
5.
Drug Deliv Transl Res ; 6(1): 1-16, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26712122

RESUMO

Local delivery of anti-HIV drugs to the colorectal mucosa, a major site of HIV replication, and their retention within mucosal tissue would allow for a reduction in dose administered, reduced dosing frequency and minimal systemic exposure. The current report describes a mucosal pre-exposure prophylaxis (mPrEP) strategy that utilizes nanocarrier conjugates (NC) consisting of poly(ethylene glycol) (PEG), amprenavir (APV), and a cell-penetrating peptide (CPP; namely Bac7, a fragment derived from bactenecin 7). APV-PEG NCs with linear PEGs (2, 5, 10, and 30 kDa) exhibited reduced (52-21%) anti-HIV-1 protease (PR) activity as compared to free APV in an enzyme-based FRET assay. In MT-2 T cells, APV-PEG3.4 kDa-FITC (APF) anti-HIV-1 activity was significantly reduced (160-fold, IC50 = 8064 nM) due to poor cell uptake, whereas it was restored (IC50 = 78.29 nM) and similar to APV (IC50 = 50.29 nM) with the addition of Bac7 to the NC (i.e., APV-PEG3.4 kDa-Bac7, APB). Flow cytometry and confocal microscopy demonstrated Bac7-PEG3.4 kDa-FITC (BPF) uptake was two- and fourfold higher than APF in MT-2 T cells and Caco-2 intestinal epithelial cells, respectively. There was no detectable punctate fluorescence in either cell line suggesting that BPF directly enters the cytosol thus avoiding endosomal entrapment. After colorectal administration in mice, BPF mucosal concentrations were 21-fold higher than APF concentrations. BPF concentrations also remained constant for the 5 days of the study suggesting that (1) the NC's structural characteristics (i.e., the size of the PEG carrier and the presence of a CPP) significantly influenced tissue persistence, and (2) the NCs were probably lodged in the lamina propria since the average rodent colon mucosal cell turnover time is 2-3 days. These encouraging results suggest that Bac7 functionalized NCs delivered locally to the colorectal mucosa may form drug delivery depots that are capable of sustaining colorectal drug concentrations. Although the exact mechanisms for tissue persistence are unclear and will require further study, these results provide proof-of-concept feasibility for mPrEP.


Assuntos
Carbamatos/administração & dosagem , Infecções por HIV/prevenção & controle , Inibidores da Protease de HIV/administração & dosagem , HIV-1 , Mucosa Intestinal/virologia , Nanoconjugados/administração & dosagem , Profilaxia Pré-Exposição/métodos , Sulfonamidas/administração & dosagem , Administração Retal , Animais , Células CACO-2 , Peptídeos Penetradores de Células/administração & dosagem , Furanos , Protease de HIV/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos , Peptídeos Cíclicos/administração & dosagem , Polietilenoglicóis/administração & dosagem
6.
J Pharm Pract ; 28(6): 577-84, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24443313

RESUMO

PURPOSE: To develop and implement a research elective course to enhance skills of pharmacy students on primary literature evaluation and evidence-based practice on dietary supplements and generate scholarly publications. METHODS: A 2 credit hour independent research elective course was designed and implemented in the third-year doctor of pharmacy curriculum. The course involved student-led research activities that included formulating research project, reviewing of primary literature, collection and evaluation of data, and writing of review articles for publication in peer-reviewed journals. An online survey was administered to evaluate students' perceptions of the course. RESULTS: Students successfully completed the course. The course resulted in peer-reviewed publications through student-faculty collaboration. Pharmacy students enrolled in the elective course perceived that the course helped them enhance their analytical reasoning, critical thinking and drug-literature evaluation skills, gain evidence-based knowledge, and apply the knowledge into practice during their advanced pharmacy practice experiences community pharmacy rotations. CONCLUSIONS: The course provided opportunity to the pharmacy students to not only critically search and evaluate the literature but also publish in peer-reviewed journals. Other pharmacy schools/colleges can adopt this course model to create opportunities for student-faculty collaborations toward scholarly accomplishments.


Assuntos
Suplementos Nutricionais , Educação em Farmácia , Pesquisa/educação , Estudantes de Farmácia , Currículo , Avaliação Educacional , Humanos , Publicações Periódicas como Assunto
7.
Pharm Res ; 29(11): 3156-68, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22736232

RESUMO

PURPOSE: Use of coital-dependent products to prevent HIV-1 transmission has resulted in mixed success. We hypothesize that incorporation of antiviral drug candidates into a novel controlled delivery system will prolong their activity, making their use coital independent, thus increasing their chance of prophylactic success. METHODS: Tenofovir, emtricitabine, and C5A peptide HIV microbicides were mechanically incorporated into matrices comprising a series of subliming solids. Matrix sublimation rates and drug release rates were measured in three in vitro and one in vivo environments intended to model human vaginal interior. Antiviral activity studies evaluating matrix incorporated microbicides were performed using in vitro cell cultures and human ectocervical explants. RESULTS: Drug release rates were identical to matrix sublimation rates, and were zero order. Differences in matrix material sublimation enthalpies determined drug release and matrix erosion rates in a thermodynamically definable manner, in vitro and in vivo. Durations of release ranging from several days to several months were readily achieved. Prolonged duration of anti HIV-1 activity was shown for matrix incorporated microbicides, using ectocervical explant and cell culture models of HIV-1 infection. CONCLUSION: Subliming solid matrices show promise as a delivery system providing multi month intravaginal release of a wide range of HIV-1 microbicides.


Assuntos
Fármacos Anti-HIV/administração & dosagem , Fármacos Anti-HIV/química , Sistemas de Liberação de Medicamentos/métodos , Infecções por HIV/prevenção & controle , Adenina/administração & dosagem , Adenina/análogos & derivados , Animais , Células Cultivadas , Dispositivos Anticoncepcionais Femininos , Preparações de Ação Retardada , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Emtricitabina , Feminino , Infecções por HIV/transmissão , HIV-1/efeitos dos fármacos , Humanos , Macrófagos/efeitos dos fármacos , Monócitos/efeitos dos fármacos , Organofosfonatos/administração & dosagem , Ovinos , Relação Estrutura-Atividade , Sublimação Química , Linfócitos T/efeitos dos fármacos , Tenofovir
8.
Antimicrob Agents Chemother ; 56(6): 3336-43, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22430971

RESUMO

We have identified a short amphipathic helical peptide, called C5A, which exhibits potent microbicidal activities in vitro and which offers protection from vaginal HIV transmission in vivo in a humanized mouse model. However, there are many obstacles to overcome before C5A can be considered a true microbicidal candidate. First, it must be stabilized against enzymatic degradation in a continuously warm and moist environment. Second, it must be delivered in a controlled manner to achieve long-term and coitally independent efficacy. We demonstrate in this in vitro study that the combination of two matrices with different subliming properties ((hexamethylcyclotrisiloxane [HMCS] and cyclododecane [CDD]) containing 10% labile C5A yielded the best results in terms of controlled release and preserved anti-HIV activity of the peptide when pre-exposed to cell-free medium or cell culture at body temperature for up to 2 months.


Assuntos
Antivirais/farmacologia , HIV/efeitos dos fármacos , Peptídeos/farmacologia , Antivirais/química , Linhagem Celular , Células Cultivadas , Humanos , Peptídeos/química , Estrutura Secundária de Proteína
9.
Biomaterials ; 31(26): 6675-84, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20561680

RESUMO

Two vinyl sulfone functionalized crosslinkers were developed for the purpose of preparing degradable poly(ethylene glycol) (PEG) hydrogels (EMXL and GABA-EMXL hydrogels). A self-elimination degradation mechanism in which an N-terminal residue of a glutamine is converted to pyroglutamic acid with subsequent release of diamino PEG (DAP) is proposed. The hydrogels were formed via Michael addition by mixing degradable or nondegradable crosslinkers and copolymer {4% w/v; poly[PEG-alt-poly(mercapto-succinic acid)]} at room temperature in phosphate buffer (PB, pH = 7.4). Hydrogel degradation was characterized by assessing diamino PEG release and examining morphological changes as well as the swelling and weight loss ratio under physiological conditions (37 degrees C). Degradation of EMXL and GABA-EMXL hydrogels occurred by surface erosion (confirmed by SEM). GABA-EMXL degradation was significantly faster (approximately 3-fold) than EMXL; however, the degradation of both hydrogels in mouse plasma was 12-times slower than in PBS. The slower degradation rate in plasma as compared to buffer is consistent with the presence of gamma-glutamyltransferase, gamma-glutamylcyclotransferase and/or glutaminyl cyclase (QC), which have been shown to suppress pyroglutamic acid formation. The current studies suggest that EMXL and GABA-EMXL hydrogels may have biomedical applications where 1-2 week degradation timeframes are optimal.


Assuntos
Materiais Biocompatíveis/farmacologia , Polietilenoglicóis/farmacologia , Animais , Materiais Biocompatíveis/química , Reagentes de Ligações Cruzadas/química , Reagentes de Ligações Cruzadas/farmacologia , Dextranos/metabolismo , Fluorescamina/metabolismo , Fluoresceína-5-Isotiocianato/metabolismo , Hidrogéis , Camundongos , Microscopia Eletrônica de Varredura , Polietilenoglicóis/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Propriedades de Superfície/efeitos dos fármacos , Fatores de Tempo
10.
Adv Drug Deliv Rev ; 62(4-5): 518-31, 2010 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-19941919

RESUMO

A variety of nanocarriers such as bioconjugates, dendrimers, liposomes, and nanoparticles have been widely evaluated as potential targeted drug delivery systems. Passive targeting of nanoscale carriers is based on a size-flow-filtration phenomenon that is usually limited to tumors, the reticular endothelial system, and possibly lymph nodes (LNs). In fact, targeting the delivery of drugs to pivotal physiological sites such as the lymph nodes has emerged as a promising strategy in treating HIV disease. Ligands for specific cell surface receptors can be displayed on nanocarriers in order to achieve active targeting. The approach has been extensively used preclinically in cancer where certain receptors are over-expressed at various stages of the disease. Unfortunately, markers of HIV infection are lacking and latently infected cells do not show any signs of infection on their surface. However, the disease naturally targets only a few cell types. The HIV receptor CD4, coreceptors (CCR5 and CXCR4), and some receptors relatively specific for macrophages provide potentially valuable surface targets for drug delivery to all susceptible cells in patients infected by HIV. This review focuses on nanoscale targeting with an emphasis on surface modifications of drug delivery nanocarriers for active targeting. A number of related issues, including HIV biology, targets, pharmacokinetics, and intracellular fate as well as literature-cited examples of emerging surface-modified targeted carrier systems are discussed.


Assuntos
Fármacos Anti-HIV/administração & dosagem , Fármacos Anti-HIV/química , Portadores de Fármacos/química , Nanopartículas/química , Receptores de Superfície Celular/metabolismo , Fármacos Anti-HIV/uso terapêutico , Dendrímeros , Sistemas de Liberação de Medicamentos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/patologia , Humanos , Lipossomos , Linfonodos/metabolismo , Macrófagos/efeitos dos fármacos , Receptores de Superfície Celular/efeitos dos fármacos
11.
Biomaterials ; 30(29): 5649-59, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19647312

RESUMO

In the current study, the design, synthetic feasibility and biochemical characterization of biodegradable peptidic PEG-based nanocarriers are described. The components were selected to influence the body elimination pathway upon nanocarrier biodegradation. Two prototypical nanocarriers were prepared using non-PEGylated and PEGylated peptidic cores [CH(3)CO-(Lys-betaAla-betaAla)(X)-Cys-CONH(2) (X=2, 4)]. A homodimeric nanocarrier with 4 copies of fluorescein-PEG5kDa was synthesized by linking two PEGylated peptidic cores (X=2) using a disulfide bond. A dual labeled heterodimeric nanocarrier with 2 copies of fluorescein-PEG5kDa and 4 copies of Texas Red was also synthesized. Optimum conditions for linking imaging agents, PEG, or a peptidic core to a peptidic core were determined. Significantly higher yields (69% versus 30%) of the PEGylated peptidic core were obtained by using 2 copies of beta-alanine as a spacer along with increasing DMSO concentrations, which resulted in reduced steric hindrance. Stoichiometric addition of the components was also demonstrated and found to be important for reducing polydispersity. Nanocarrier biodegradation was evaluated in simulated intracellular and extracellular/blood environments using 3 mm and 10 microm glutathione in buffer, respectively. The nanocarrier was 9-fold more stable in the extracellular environment. The results suggest selective intracellular degradation of the nanocarrier into components with known body elimination pathways.


Assuntos
Implantes Absorvíveis , Líquidos Corporais/química , Materiais Revestidos Biocompatíveis/química , Portadores de Fármacos/química , Peptídeos/química , Polietilenoglicóis/química , Dimerização , Teste de Materiais
12.
Mol Pharm ; 6(3): 836-48, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19278221

RESUMO

Cell-penetrating peptides (CPPs) can enter many types of cells and have become useful tools for introducing a variety of cargo such as exogenous peptides, proteins, and nucleic acids into cultured cells in vitro. Tat CPPs derived from the HIV-1 Tat protein are the most widely used among the arginine-rich CPPs. Even though CPPs hold considerable promise for drug delivery, poor biological stability and high in vivo clearance may limit their effectiveness for delivering cargo. Therefore, we utilize a retro-inverso form of a Tat peptide, R.I.-CKTat9, which is proteolytically stable. In the current study, the cellular entry mechanism of this arginine-rich CPP is investigated. Fluorescently labeled R.I.-CKTat9 entered HeLa cells in a concentration- and energy-dependent manner demonstrating both diffuse and punctate (vesicular) appearance inside the cells. The labeled R.I.-CKTat9 colocalized with labeled transferrin in the punctate structure, suggesting that the peptide enters HeLa cells by clathrin-dependent endocytosis. Incubation of cells with an isotonic/high K(+) buffer (KPBS) or an NH(4)Cl solution abolished the diffuse but not the punctate fluorescence, suggesting that membrane potential plays a critical role. This result also suggests that the flux originates from the endosome, not the extracellular space, and relies on the acidity of the endosome. Impairment of clathrin-mediated endocytosis by RNAi with clathrin heavy chain function and endocytosis inhibitors greatly reduced or completely abolished both diffuse and punctate fluorescence, further supporting a single route of endocytosis and subsequent endosomal escape. Since cells in the mitotic (M) phase shut down endocytosis but maintain plasma membrane potential, this property was used to further confirm the endocytic mechanism. Direct measurement of plasma membrane potential confirmed its persistence in M phase arrested HeLa cells. Consistent with our working hypothesis, these cells did not show any vesicular nor diffuse fluorescence of labeled R.I.-CKTat9, providing compelling evidence for the sequential steps of endocytosis and endosomal escape. Binding of labeled R.I.-CKTat9 to the surface of HeLa cells at 0 degrees C was reduced under the mildly acidic conditions of early endosomes, suggesting an acidity-dependent endosomal escape mechanism. Overall, these results indicate that both endocytosis and membrane potential are required for R.I.-CKTat9 entry into HeLa cells and suggest that translocation occurs at the endosomal membrane.


Assuntos
Endocitose/fisiologia , Produtos do Gene tat/metabolismo , Potenciais da Membrana/fisiologia , Fragmentos de Peptídeos/metabolismo , Transporte Biológico/genética , Transporte Biológico/fisiologia , Clatrina/genética , Clatrina/fisiologia , Produtos do Gene tat/síntese química , Produtos do Gene tat/química , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Microscopia Confocal , Microscopia de Fluorescência , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , Ligação Proteica , Interferência de RNA
13.
AIDS Res Ther ; 3: 12, 2006 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-16635263

RESUMO

BACKGROUND: Current anti-AIDS therapeutic agents and treatment regimens can provide a dramatically improved quality of life for HIV-positive people, many of whom have no detectable viral load for prolonged periods of time. Despite this, curing AIDS remains an elusive goal, partially due to the occurrence of drug resistance. Since the development of resistance is linked to, among other things, fluctuating drug levels, our long-term goal has been to develop nanotechnology-based drug delivery systems that can improve therapy by more precisely controlling drug concentrations in target cells. The theme of the current study is to investigate the value of combining AIDS drugs and modifiers of cellular uptake into macromolecular conjugates having novel pharmacological properties. RESULTS: Bioconjugates were prepared from different combinations of the approved drug, saquinavir, the antiviral agent, R.I.CK-Tat9, the polymeric carrier, poly(ethylene) glycol and the cell uptake enhancer, biotin. Anti-HIV activities were measured in MT-2 cells, an HTLV-1-transformed human lymphoid cell line, infected with HIV-1 strain Vbu 3, while parallel studies were performed in uninfected cells to determine cellular toxicity. For example, R.I.CK-Tat9 was 60 times more potent than L-Tat9 while the addition of biotin resulted in a prodrug that was 2850 times more potent than L-Tat9. Flow cytometry and confocal microscopy studies suggest that variations in intracellular uptake and intracellular localization, as well as synergistic inhibitory effects of SQV and Tat peptides, contributed to the unexpected and substantial differences in antiviral activity. CONCLUSION: Our results demonstrate that highly potent nanoscale multi-drug conjugates with low non-specific toxicity can be produced by combining moieties with anti-HIV agents for different targets onto macromolecules having improved delivery properties.

14.
Bioconjug Chem ; 15(6): 1322-33, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15546199

RESUMO

Various poly(ethylene glycol)(PEG)-based prodrug conjugates of the HIV-1 protease inhibitor (PI) saquinavir (SQV) were prepared using several types of chemical groups potentially capable of modifying its pharmacokinetic properties. These prodrug conjugates included SQV-cysteine-PEG3400, SQV-cysteine-PEG3400-biotin, SQV-cysteine(R.I.CK-Tat9) [a cationic retro-inverso-cysteine-lysine-Tat nonapeptide]-PEG3400, and SQV-cysteine(R.I.CK(stearate)-Tat9)-PEG3400. SQV was linked to cysteine to form a releasable SQV-cysteine ester bond in all of the conjugates. The amino group of the cysteine moiety provided an attachment site for a slower-degrading amide bond with N-hydroxysuccinimide-activated forms of PEG- and PEG-biotin. Disulfide bonds were used to attach the cationic peptides, R.I.CK-Tat9 and R.I.CK(stearate)-Tat9 to the cysteine moiety in order to provide cell-specific release. An assay was established and validated for measuring the activity of SQV and other protease inhibitors in biological samples. In this assay, cleavage of an internally quenched fluorescent substrate, Arg-Glu(EDANS)-Ser-Gln-Asn-Tyr-Pro-Ile-Val-Gly-Lys(DABCYL)-Arg by HIV-1 protease was inhibited by SQV in a dose-dependent manner at concentrations of 0.05-0.5 microM. All prodrug conjugates were shown to be inactive in this assay until the ester bond was cleaved and active SQV was released. The prodrug reconversion half-lives in 0.1 N HCl, phosphate-buffered saline (PBS) at pH 7.4 and in spiked plasma at 37 degrees C were 9, 14, and 0.9 h, respectively. The anti-HIV-1 activity (ED(50)) of the PEG-based SQV prodrug conjugates was evaluated in MT-2 cells using an MTT assay. The activity of conjugated SQV was reduced (ED(50) = 900 nM) for the PEG only conjugate, but restored with the addition of biotin (ED(50) = 125 nM), R.I.CK-Tat9 (ED(50) = 15 nM), and R.I.CK(stearate)-Tat9 (ED(50) = 62 nM) as compared to maximum achievable anti-HIV-1 activity (unconjugated SQV, control, ED(50) = 15 nM), suggesting enhanced cellular uptake of conjugates. Cytotoxicity (LD(50)) was assessed for all prodrug conjugates using non-HIV-1 infected cells and was found to be in the micromolar range. The difference between the LD(50) and ED(50) suggests a favorable therapeutic index for the prodrug conjugates. In conclusion, these promising initial results demonstrate that the reconversion of the conjugate prodrugs was complete and that active SQV was released. Since the major delivery advantages of PEG prodrug conjugates can only be observed in vivo, issues of reconversion and elimination half-lives in plasma will have to be further studied in an in vivo model. The current results also demonstrate that the protease inhibition assay is a simple yet effective bioanalytical tool that can be used to assess the release and anti-HIV-1 activity of HIV-1 PIs from their prodrug forms.


Assuntos
Fármacos Anti-HIV/síntese química , Inibidores da Protease de HIV/síntese química , HIV-1/efeitos dos fármacos , Polietilenoglicóis/síntese química , Pró-Fármacos/síntese química , Saquinavir/síntese química , Fármacos Anti-HIV/administração & dosagem , Fármacos Anti-HIV/metabolismo , Linhagem Celular Tumoral , Inibidores da Protease de HIV/administração & dosagem , Inibidores da Protease de HIV/metabolismo , HIV-1/metabolismo , Humanos , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/metabolismo , Pró-Fármacos/administração & dosagem , Pró-Fármacos/metabolismo , Saquinavir/administração & dosagem , Saquinavir/metabolismo
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