1.3
Ensayos clínicos: Descripción general
El desarrollo clínico se centra en cómo el medicamento interactuará con el cuerpo humano y abarca cuatro fases clave de los ensayos clínicos, cada una…
Los ensayos clínicos son estudios de investigación que evalúan las propiedades farmacológicas de un fármaco candidato en humanos. Estos ensayos se llevan a cabo en varias fases.
En la fase I, se prueban de cinco a diez medicamentos candidatos de estudios preclínicos exitosos en un pequeño grupo de individuos o pacientes sanos para evaluar varios efectos, como la toxicidad potencial, los efectos secundarios, la farmacocinética y la farmacodinamia.
Los candidatos exitosos de la fase I se prueban en la fase II en cien a trescientos pacientes para monitorear la eficacia del medicamento y la regulación de la dosis.
Los candidatos que superan la fase II de cribado se someten a pruebas en la fase III para determinar su seguridad y eficacia. Los ensayos de fase III son estudios doble ciego realizados en miles de pacientes en muchos centros.
Después de un ensayo de fase III exitoso, se presenta una solicitud de nuevo medicamento a la FDA para su aprobación de comercialización.
Una vez que el medicamento es aprobado por la FDA, el fabricante produce y coloca el medicamento en el mercado.
La vigilancia posterior a la comercialización, o fase IV, se realiza para estudiar los efectos adversos a largo plazo o poco frecuentes del medicamento.
View the full transcript and gain access to JoVE Core videos
Q1: What happens in phase I of a clinical trial?
Phase I tests five to ten candidate drugs on a small group of healthy individuals or patients to evaluate toxicity, side effects, pharmacokinetics, and pharmacodynamics. This initial phase determines whether the drug is safe enough to proceed to larger patient populations and establishes baseline tolerability and safety data for advancement.
Q2: How do phase II and phase III clinical trials differ?
Phase II expands testing to 100-300 patients to monitor drug efficacy and dosage regulation. Phase III involves double-blind, randomized trials with thousands of patients across multiple centers to comprehensively compare the new drug against existing alternatives or placebos, making it more costly and time-consuming than phase II.
Q3: What is the purpose of phase IV trials?
Phase IV, or postmarketing surveillance, monitors long-term and rare adverse effects in large patient populations after FDA approval. This ongoing phase ensures drug safety continues to be tracked throughout its use in the general population and identifies effects that may not appear in earlier trial phases.
Q4: What happens after a successful phase III trial?
After phase III success, a New Drug Application is submitted to the FDA with a detailed dossier of preclinical and clinical data. The FDA reviews the submission, and approval can take a year or longer, with approximately two-thirds of submissions receiving marketing approval for commercial distribution.
Q5: How long does the entire drug development process take?
The complete drug development process, including clinical trials, spans 7 to 12 years. This extended timeline reflects the rigorous testing required across preclinical development overview phases, multiple clinical trial phases, and regulatory review before a drug reaches the market for patient use.
Q6: What standards must clinical trials follow?
Clinical trials must adhere to Good Clinical Practice guidelines, ensuring meticulous patient group selection, data collection, statistical analysis, and documentation. Phase III trials increasingly incorporate pharmacoeconomic analysis to assess both clinical and economic benefits of new drugs before regulatory submission and approval.
Q7: What determines whether a drug candidate advances from phase I testing?
Successful candidates from phase I demonstrate acceptable safety profiles and provide data on pharmacokinetics and pharmacodynamics. Only drugs showing sufficient tolerability and lack of prohibitive toxicity advance to phase II testing in larger patient groups to evaluate therapeutic efficacy and optimal dosage.