Medicinal chemistry filters for compound triage. Apply drug-likeness rules (Lipinski, Veber, CNS), structural alert catalogs (PAINS, NIBR, ChEMBL), complexity metrics, and the medchem query language for library filtering.
npx skills add https://github.com/K-Dense-AI/scientific-agent-skills --skill medchem
Medchem is a Python library from datamol-io for molecular filtering and prioritization in drug discovery. Apply literature-derived drug-likeness rules, named alert catalogs, complexity thresholds, chemical-group detection, and a custom query language to triage compound libraries at scale. Filters are context-specific guidelines — combine with domain expertise and target knowledge.
Version note: Examples target medchem 2.0.5 (PyPI stable, Nov 2024). Requires Python ≥3.9. Depends on datamol and RDKit (installed automatically). RuleFilters and structural filter classes return pandas DataFrames. Lilly demerits require optional native binaries (mamba install lilly-medchem-rules).
This skill should be used when:
uv pip install medchem datamol
Optional — Eli Lilly demerit filter (requires conda-forge native binaries):
mamba install -c conda-forge lilly-medchem-rules
Apply established drug-likeness rules via medchem.rules.
List available rules:
import medchem as mc
mc.rules.RuleFilters.list_available_rules_names()
# ['rule_of_five', 'rule_of_five_beyond', 'rule_of_four', 'rule_of_three', ...]
Single rule on one molecule:
import datamol as dm
import medchem as mc
smiles = "CC(=O)OC1=CC=CC=C1C(=O)O" # aspirin
mc.rules.basic_rules.rule_of_five(smiles) # True
mc.rules.basic_rules.rule_of_cns(smiles) # True
mc.rules.basic_rules.rule_of_veber(smiles) # True
Multiple rules with RuleFilters (returns a DataFrame):
import datamol as dm
import medchem as mc
mols = [dm.to_mol(s) for s in smiles_list]
rfilter = mc.rules.RuleFilters(
rule_list=["rule_of_five", "rule_of_oprea", "rule_of_cns", "rule_of_leadlike_soft"]
)
df = rfilter(mols=mols, n_jobs=-1, progress=True, keep_props=False)
# Columns: mol, pass_all, pass_any, rule_of_five, rule_of_oprea, ...
passing = df[df["pass_all"]]
Use keep_props=True to include computed descriptors (mw, clogp, tpsa, etc.) in the result.
Detect problematic patterns with medchem.structural. Both classes return DataFrames with pass_filter, status, and reasons columns.
Common alerts (ChEMBL-derived rule sets):
import medchem as mc
alert_filter = mc.structural.CommonAlertsFilters()
df = alert_filter(mols=mol_list, n_jobs=-1, progress=True)
# df columns: mol, pass_filter, status, reasons
clean = df[df["pass_filter"]]
NIBR filters (Novartis screening-deck curation):
nibr_filter = mc.structural.NIBRFilters()
df = nibr_filter(mols=mol_list, n_jobs=-1, progress=True)
# df columns: mol, pass_filter, status, severity, reasons, n_covalent_motif, special_mol
Compounds with severity >= 10 are excluded by default (see NIBR paper).
Use medchem.catalogs.NamedCatalogs for RDKit FilterCatalog instances, or the functional API:
import medchem as mc
# List available named catalogs
mc.catalogs.list_named_catalogs()
# ['tox', 'pains', 'pains_a', 'brenk', 'nibr', 'zinc', ...]
# Functional API — True means molecule passes (no alert match)
passes = mc.functional.alert_filter(mols=mol_list, alerts=["pains"], n_jobs=-1)
# Or via catalog objects
passes = mc.functional.catalog_filter(
mols=mol_list,
catalogs=[mc.catalogs.NamedCatalogs.pains()],
n_jobs=-1,
)
medchem.functional provides one-call wrappers that return boolean masks (True = passes):
import medchem as mc
mc.functional.rules_filter(mols=mol_list, rules=["rule_of_five", "rule_of_cns"], n_jobs=-1)
mc.functional.nibr_filter(mols=mol_list, max_severity=10, n_jobs=-1)
mc.functional.alert_filter(mols=mol_list, alerts=["pains", "brenk"], n_jobs=-1)
mc.functional.complexity_filter(mols=mol_list, complexity_metric="bertz", limit="99", n_jobs=-1)
Other helpers: catalog_filter, chemical_group_filter, lilly_demerit_filter (requires optional binaries), macrocycle_filter, bredt_filter, protecting_groups_filter, and more.
Detect functional groups and curated pattern collections via medchem.groups:
import medchem as mc
# Browse available group collections
mc.groups.list_default_chemical_groups()
# ['privileged_scaffolds', 'common_warhead_covalent_inhibitors', 'rings_in_drugs', ...]
group = mc.groups.ChemicalGroup(groups=["privileged_scaffolds"])
group.has_match(mol) # bool
group.get_matches(mol) # dict of group → atom indices
group.filter(mols) # molecules matching the group
# Returns molecules that do NOT match the group
mc.functional.chemical_group_filter(mols=mol_list, chemical_group=group, n_jobs=-1)
Custom groups can be loaded from a file via groups_db (CSV with smiles/smarts, name, group columns).
Compare complexity metrics to precomputed ZINC-15 percentile thresholds:
import medchem as mc
# Single molecule
cf = mc.complexity.ComplexityFilter(limit="99", complexity_metric="bertz")
cf(mol) # True if below 99th-percentile threshold
# Batch via functional API
mc.functional.complexity_filter(
mols=mol_list,
complexity_metric="bertz", # also: sas, qed, whitlock, barone, smcm, twc
limit="99",
n_jobs=-1,
)
# Direct metric functions
mc.complexity.WhitlockCT(mol)
mc.complexity.BaroneCT(mol)
medchem.constraints.Constraints matches a core scaffold and applies per-atom constraint functions — not simple MW/LogP ranges. For property bounds, use RuleFilters, descriptors via mc.rules.list_descriptors(), or the query language.
import datamol as dm
import medchem as mc
core = dm.to_mol("c1ccccc1")
constraints = mc.constraints.Constraints(
core=core,
constraint_fns={"query": lambda mol, atom_idx, query: ...},
)
constraints(mol)
Build multi-criteria filters with medchem.query.QueryFilter:
import medchem as mc
# Rule + alert combination
qf = mc.query.QueryFilter('MATCHRULE("rule_of_five") AND NOT HASALERT("pains")')
mask = qf(mols=mol_list, n_jobs=-1) # list[bool]
# CNS-like with property bounds
qf = mc.query.QueryFilter('MATCHRULE("rule_of_cns") AND HASPROP("tpsa", <=, 90)')
mask = qf(mols=mol_list, n_jobs=-1)
Query syntax:
MATCHRULE("rule_of_five") — apply a named ruleHASALERT("pains") — match a named catalog (pains, brenk, nibr, tox, …)HASPROP("mw", <, 500) — compare a descriptor (unquoted comparator)HASGROUP("privileged_scaffolds") — match a chemical groupHASSUBSTRUCTURE("c1ccccc1") — substructure matchAND, OR, NOTList available descriptors: mc.rules.list_descriptors()
import datamol as dm
import medchem as mc
import pandas as pd
df = pd.read_csv("compounds.csv")
mols = [dm.to_mol(s) for s in df["smiles"]]
# Drug-likeness rules
rules_df = mc.rules.RuleFilters(rule_list=["rule_of_five", "rule_of_veber"])(mols=mols, n_jobs=-1)
# PAINS + common alerts via query
qf = mc.query.QueryFilter('MATCHRULE("rule_of_five") AND NOT HASALERT("pains")')
pass_mask = qf(mols=mols, n_jobs=-1)
df["passes_rules"] = rules_df["pass_all"].values
df["drug_like"] = pass_mask
filtered_df = df[df["drug_like"]]
filtered_df.to_csv("filtered_compounds.csv", index=False)
import medchem as mc
rules_df = mc.rules.RuleFilters(rule_list=["rule_of_leadlike_soft"])(mols=candidates, n_jobs=-1)
nibr_df = mc.structural.NIBRFilters()(mols=candidates, n_jobs=-1)
complex_mask = mc.functional.complexity_filter(
mols=candidates, complexity_metric="bertz", limit="95", n_jobs=-1
)
passes = (
rules_df["pass_all"]
& nibr_df["pass_filter"]
& complex_mask
)
import medchem as mc
group = mc.groups.ChemicalGroup(groups=["common_warhead_covalent_inhibitors"])
matches = [group.has_match(mol) for mol in mol_list]
warhead_mols = [mol for mol, m in zip(mol_list, matches) if m]
n_jobs=-1 for libraries >1000 molecules.RuleFilters and structural classes return DataFrames; functional helpers return boolean arrays.lilly-medchem-rules separately; default max demerits is 160 in the functional API.status, reasons, and severity columns for audit trails.Module-by-module API reference with signatures, return types, and patterns.
Catalog of available rules, alert sets, complexity metrics, and filter selection guidelines.
Batch filtering script for CSV/TSV/SDF/SMILES inputs with configurable rules, alerts, and complexity thresholds.
uv run python scripts/filter_molecules.py input.csv \
--rules rule_of_five,rule_of_cns --pains --nibr --output filtered.csv
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Take k-dense-ai/medchem from the repository into ~/.claude/skills for personal
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same name cannot sit side by side — one of them will be ignored.
The instructions reference pip, uv.
Without those the skill loads but fails at the first command.