The assessment of safety pharmacology is primarily governed by the ICH S7A (Core Battery) and ICH S7B (Cardiovascular) guidelines. These studies are designed to investigate potential undesirable pharmacodynamic effects on vital functions before human exposure.
Here is the comprehensive list of safety pharmacology studies categorized by their regulatory priority.
1. The Core Battery (Required for most INDs)
These studies must be conducted prior to First-in-Human (FIH) trials to assess effects on the three vital organ systems.
Central Nervous System (CNS):Functional Observational Battery (FOB) or Modified Irwin Test: Assesses behavioral changes, motor activity, coordination, sensory/motor reflexes, and body temperature.
Cardiovascular System (CV):In Vivo Telemetry: Continuous monitoring of blood pressure, heart rate, and Electrocardiogram (ECG) in conscious, freely moving non-rodents (typically dogs or primates).
In Vitro hERG Assay (ICH S7B): Assessment of the $I_{Kr}$ potassium current to evaluate the risk of QT interval prolongation.
Respiratory System: Plethysmography: Measures respiratory rate and tidal volume (and/or minute volume) in conscious animals. Often integrated with cardiovascular telemetry studies.
In modern drug development, there is a strong trend toward Integrated Safety Pharmacology. This involves adding SP endpoints (like telemetry or specialized ECGs) into the General Toxicology repeat-dose studies to reduce animal use and observe effects over chronic exposure.
2. Supplemental Safety Pharmacology Studies
These are conducted if the core battery or existing data (e.g., from general toxicology) raises concerns about specific organ systems.
Renal/Urinary System: Evaluation of urinary volume, specific gravity, osmolality, pH, protein, cytology, and electrolyte balance (fractional excretion).
Gastrointestinal (GI) System: Studies on gastric secretion, GI injury potential, bile secretion, and transit time (in vivo or in vitro ileal contraction).
Autonomic Nervous System: Assessment of receptor binding and functional responses to agonists/antagonists.
3. Follow-up Safety Pharmacology Studies
These provide a deeper dive into mechanisms of action if adverse effects are observed in the core battery or clinical trials
CNS Follow-up: Quantitative motor performance, EEG (electroencephalography), learning and memory assessments, or seizure liability.
CV Follow-up: Cardiac output, ventricular contractility ($dP/dt$), and peripheral vascular resistance.
Respiratory Follow-up: Airway resistance, lung compliance, and blood gas analysis ($pCO_{2}, pO_{2}, pH$).
4. Specialized Assessments
Proarrhythmia (CiPA): The Comprehensive In Vitro Proarrhythmia Assay (CiPA) is often used for a more nuanced look at cardiac ion channels ($hNav1.5$, $hCav1.2$) beyond just hERG.
Abuse Liability: Required for drugs that cross the Blood-Brain Barrier (BBB) and show CNS activity (includes self-administration and drug discrimination studies).
| SP Study Name | Purpose | Key Endpoints | When is it Needed | Brief Study Design |
| CNS (Irwin/FOB) | Assess acute impact on behavior and neurological function. | Motor activity, coordination, tremors, body temp, reflexes. | Core Battery: Required for all INDs. | Single-dose in rats (3 levels). Observations at $T_{max}$ and multiple time points. |
| CV Telemetry | Evaluate hemodynamics and cardiac rhythm in vivo. | Blood pressure (systolic/diastolic), heart rate, Lead II ECG (QT interval). | Core Battery: Required for all INDs. | Conscious, non-rodents (dogs/monkeys) with implanted transmitters; crossover design. |
| hERG Assay | Screen for $I_{Kr}$ potassium channel inhibition (QT risk). | % inhibition of tail current at multiple concentrations. | Core Battery: Required for all INDs. | In vitro patch-clamp using hERG-expressing cells (e.g., HEK293). |
| Respiratory (Plethysmography) | Assess pulmonary function and breathing patterns. | Respiratory rate, tidal volume, minute volume. | Core Battery: Required for all INDs. | Conscious rats in sealed chambers measuring pressure changes during breathing. |
| Renal Assessment | Evaluate drug impact on kidney function/electrolytes. | Urine volume, pH, osmolality, electrolytes ($Na^+, K^+, Cl^-$). | Supplemental: If renal concerns arise from tox or ADME. | Rats housed in metabolic cages for 6–24 hours post-dose for sample collection. |
| GI Assessment | Detect changes in gastric motility or secretion. | Gastric emptying rate, intestinal transit, gastric pH. | Supplemental: If GI symptoms are noted in general tox. | Charcoal meal transit in rodents or gastric secretion analysis (pyloric ligation). |
| Abuse Liability | Determine potential for addiction or dependence. | Self-administration rate, withdrawal signs, drug discrimination. | Specialized: For CNS-active drugs that cross the BBB. | Behavioral testing in rodents/primates (e.g., lever pressing for reward). |
| Follow-up CV | Deeper probe into cardiac contractility or output. | Cardiac output, stroke volume, $dP/dt$ (ventricular pressure). | Follow-up: If telemetry shows BP/HR abnormalities. | Anesthetized or conscious instrumented non-rodents for invasive pressure monitoring. |