Course program
General principles
Aims and areas of application of Toxicology, particularly in the pharmaceutical field.
Relationship between exposure and toxic effect. Threshold doses. Individual sensitivity: influence of endogenous factors (age, sex, genotype). Pathology-dependent toxicity: kinetic (renal or hepatic failure) and non-kinetic factors; importance for drugs: contraindications and special warnings. Environmental factors: co-exposures, toxicokinetic and toxicodynamic interactions. Acute, chronic, delayed toxicity. Mechanisms of tolerance, rebound.
Mechanisms of toxicity.
Specific mechanisms, mediated by interaction with receptors. Non-specific mechanisms; toxicity from radicals and electrophiles. Cellular, systemic, functional toxicity. Main mechanisms of cellular toxicity. Reversible and irreversible effects. Damage caused by the body's response. Inflammation and fibrosis.
Pharmacokinetics and toxicokinetics
Purposes of kinetic studies.
Importance of drug metabolism for the elimination of activity; bioactivation. General mechanisms: passive diffusion, transporters. Order I and order 0 kinetics.
Gastrointestinal absorption. Site and mechanisms of absorption. Pre-systemic elimination, first-pass effect. Malabsorption. Influence of pharmaceutical factors on dissolution and absorption and associated risks. BCS classes. Possible risks of switching from a drug to a generic (or vice versa). Interactions at the absorption level. Effect of food.
Absorption through the skin. Characteristics. Factors that influence transcutaneous absorption. Toxicological relevance.
Pulmonary absorption. Absorption of gases and vapors. Deposition of aerosols, toxicological relevance.
Distribution. Binding to plasma proteins. Possible displacement. Distribution and accumulation, effects on the rate of elimination. Role of transport systems in distribution.
Excretion routes. Renal excretion mechanisms, effect of pH. Biliary excretion, enterohepatic circulation. Excretion with milk, toxicological relevance.
Kinetic parameters related to absorption (Ka, Cmax, Tmax, bioavailability), distribution (Vd), elimination (Ke, t1/2, clearance) and their uses. Kinetics after repeated administrations; the steady state.
Exposure indices: AUC, Cmax, steady state concentration, and their use. Relationship between dose and plasma concentration; saturation kinetics, nonlinear kinetics. Relationship between concentration, time and effect. Pharmacokinetic models.
Phase 1 studies.
Metabolism of drugs and xenobiotics.
Purpose and effects on toxicity of metabolism. Metabolism and pharmacological activity. General characteristics of biotransformation reactions. Multiple metabolic pathways. Variability of metabolizing enzymes. Detoxification and activation reactions; phase I and phase II reactions.
Phase I reactions and enzymes. Cytochrome P450; formation of toxic metabolites following oxidation, dehalogenation, reduction reactions. Cytochrome P450 isoforms, their variability. Other oxidative enzymes: flavin monooxygenase (FMO), peroxidase: formation of toxic metabolites; alcohol dehydrogenase and aldehyde dehydrogenase: variability and metabolism of ethanol. Reduction reactions of quinones. Epoxide hydrolase. Studies for the characterization of metabolic pathways (reaction phenotyping). In vivo A(D)ME studies.
Phase II reactions. Glucuronidation reactions; sulfation; methylation; acetylation; conjugation with amino acids: substrates, fate of conjugated metabolites, formation of toxic metabolites. Conjugation with glutathione, glutathione-S-transferase: substrates, detoxifying power.
Influence of exogenous factors on the metabolism of drugs and other xenobiotics: enzyme induction and inhibition (pharmacokinetic interactions at the level of metabolism). Enzyme induction. Mechanisms and kinetics of induction; pharmacological and toxicological consequences. Important environmental inducers, inducing drugs. Enzyme inhibition: mechanisms and kinetics; toxicological consequences; main inhibitors of CYP450.
Genetic polymorphism of metabolizing enzymes. Polymorphism of some CYPs and phase II enzymes: pharmacological and toxicological consequences.
Influence of age and liver diseases on metabolizing capacity.
Experimental toxicological studies.
Descriptive, mechanistic, theoretical studies (structure-activity relationship). Descriptive animal studies: objectives of the studies: risk profile, relevance for humans. Detection of toxic effects; dose-response relationship; NOEL or NOAEL, LOEL or LOAEL. Species and strain dependent toxicity; choice of species to be used. Duration of studies. Acute toxicity studies: aims; lethality curves; acute exposure limits. Repeated dose toxicity studies: doses, target organs, objectives. Safety pharmacology studies. Predictability of animal studies. Doses used and extrapolation to humans.
Risk assessment (characterization)
Identification of hazard and risk assessment: general concepts. Data sources, regulations, decisions. Evaluation of information quality. Estimation of acceptable levels based on NOEL values, determination of uncertainty factors. Alternative methods to the NOEL approach for genotoxic carcinogens, Virtually Safe Dose. Applications to medicinal products: limits for residual solvents; limits for genotoxic impurities; the Threshold of Toxicological Concern (TTC).
Assessment of exposure in humans by direct and indirect methods. The LADD (Lifetime Average Daily Dose); the Margin of exposure (or safety margin). Measurement of absorbed dose; effective biological dose, biomarkers. Risk management in the pharmaceutical field.
Control of impurities in the pharmaceutical field.
Possible influence of impurities of the active substance on toxicity. Nature of impurities in the pharmaceutical field. The ICH Q3C and Q3A Guidelines. Control of related impurities: reporting, identification, qualification. Control of genotoxic impurities (ICH Guideline M7): classification criteria, calculation of acceptable exposures; the TTC.
Chemical carcinogenesis
Proto-oncogenes and tumor suppressor genes. The multi-stage model of chemical carcinogenesis: initiation, promotion, progression. Mechanisms of genetic damage. Definitions. IARC groups. Complete carcinogens, initiators, promoters, agents of progression. Genotoxic and epigenetic carcinogens. Direct and indirect carcinogens. Epigenetic carcinogens: promoters, immunosuppressants, dioxins.
Cancer and hereditary factors: high-penetrance and low-penetrance genes. Carcinogenesis and lifestyles: smoking; diet; ethanol.
Animal carcinogenesis studies. Duration, species used, transgenic strains. Problems in interpreting results. Studies for promoters.
Genotoxicity studies
Information obtainable from genotoxicity studies.
Mutagenesis tests: principles; Ames test; tests with eukaryotic cells (HPRT test, mouse lymphoma-TK assay); in vivo tests. Tests for chromosomal aberration; micronucleus test, dominant lethal test. Other genotoxicity tests: SCE test, UDS test, comet assay. Structure-activity relationship, structural alert.
Use and interpretation of genotoxicity studies. Genotoxicity studies for medicinal products.
Definitions of carcinogens based on data from different types of studies and mechanisms.
Genotoxicity studies in humans; molecular epidemiology.
Monitoring of genetic damage in human populations. Molecular epidemiology; study of the relationship between exposure and adducts or genetic damage, and between adducts or genetic damage and disease.
Reproductive and developmental toxicology
Principles: low efficiency of human reproduction, possible causes. Problems of identification and determination of ‘safe’ exposures. Critical periods of susceptibility: effects of exposure in the pre-implantation period, during organogenesis, and in the fetal period. Pathogenic mechanisms of developmental toxicity, possible mechanisms of drug-induced teratogenesis. Maternal toxicity and effects on embryo-fetal development; maternal factors influencing development. Placental toxicity. Experimental studies. Information on the risk of drug use during pregnancy. Drugs recognized as toxic for development. Regulatory classification of drugs based on data on developmental toxicity.
Developmental toxicity. Adverse effects on sexual differentiation. Effects of anti-androgens, environmental estrogens; “endocrine disruptors”. Environmental persistence and eco-toxicological effects. Substances with direct toxic effect on the gonads.
Epidemiological studies.
Objectives of epidemiology. Prevalence and incidence. Risk factors, association and causality, confounding factors. Cross-sectional or prevalence studies. Ecological studies. Case-control studies, the odds ratio and its meaning. Prospective, retrospective, single-sample cohort studies; absolute risk, relative risk, attributable risk.
Systematic errors, sampling.
Meta-analyses.
Drug toxicity and Pharmacovigilance.
Aims of pharmacovigilance. Risk minimization. Detectability of adverse drug effects in non-clinical studies (animal studies), in experimental clinical studies, in real use in the population. Definitions of adverse drug reaction and adverse event. Serious reactions, unexpected reactions. Classification of adverse reactions by type. Characteristics of type A and B reactions. Immune-mediated hypersensitivity reactions. Idiosyncrasies.
Pharmacovigilance: how to identify adverse reactions; imputability criteria ; spontaneous reports.
Preventable adverse drug reactions. Causes of preventable reactions. The Risk Management Plan.
Safety information in the Summary of Product Characteristics. Toxicity from phytotherapeutics. Toxicity from vaccines.
Prerequisites
Knowledge of: organic chemistry, biochemistry, physiology, pharmacology
Books
Lecture slides
Frequency
Attendance is not mandatory but strongly recommended
Exam mode
In the oral exam, the student is asked questions in order to evaluate the acquisition of the expected learning outcomes. The ability to make connections between the different aspects of the program will be evaluated with particular attention.
Bibliography
Pharmaceutical Toxicology, autori: Mulder e Dencker, Pharmaceutical Press
Lesson mode
Frontal lessons