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Total Drugs
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in database
Drug Classes
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pharmacological
INSTIs
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chelation modelled
NRTIs / NRTTIs
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reverse transcriptase
Drug Database
| Abbr | Drug Name | Class | pKa(s) | logP | MW |
|---|---|---|---|---|---|
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Class Distribution
logP Distribution
Drug Speciation Explorer
Henderson-Hasselbalch ionisation fractions across pH 0–14
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Compartment lines
Display
Species Fractions at Key pH Values
| Drug | Species | Stomach (1.88) | Jejunum (6.51) | Plasma (7.40) | Intracell. (7.10) |
|---|
Shore Membrane Partitioning
log₁₀(Cm/Cw) — membrane vs aqueous concentration across the GI tract
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TAF Shore Failure
TAF is an OATP1B1/B3 transporter substrate. Shore predicts poor absorption (log Cm/Cw ≈ −4 at pH 7.4), yet clinical F = 80%. Transporter-mediated uptake overrides passive diffusion entirely.
GI Compartment Heatmap
INSTI Three-Layer Mg²⁺ Chelation Model
pH-dependent ionisation × Mg²⁺ Langmuir binding × keto-enol tautomerism
INSTIs
Intracellular [Mg²⁺] free
Three-Layer Model
Layer 1: Henderson-Hasselbalch α_HHLayer 2: Mg²⁺ Langmuir θ = [Mg²⁺]/(Kd+[Mg²⁺])
Layer 3: Keto-enol f_enol (RAL & EVG only)
α_eff = α_HH × θ × f_enol
Overlay
Quantitative Summary at pH 7.1
| INSTI | pKa | Kd (μM) | Keto-Enol | α_HH | θ_Mg | f_enol | α_eff | Fold vs H-H |
|---|
DTG, CAB, BIC Dominate
Pre-organised chelation pharmacophores (no keto-enol penalty) combined with lower Kd values give DTG, CAB and BIC ~60–70% binding efficiency at intracellular pH 7.1. RAL and EVG suffer an additional keto-enol tautomerism penalty (f_enol < 1), reducing effective fraction by 24–37%.
Prodrug Trilogy: TFV → TDF → TAF
Ionisation · Shore partitioning · Clinical bioavailability — the evolution of Tenofovir
| Drug | Species | Stomach (1.88) | Jejunum (6.51) | Plasma (7.40) |
|---|
Shore Model Failure in TAF
The Shore model is a passive diffusion model. It predicts membrane partitioning based purely on neutral fraction × logP. TAF's OATP1B1/B3 hepatic uptake transporter bypasses this entirely, achieving 10 mg TAF ≡ 300 mg TDF in clinical practice. This is a landmark case of pharmacogenomics overriding physicochemical prediction.
Peptide & Monoclonal Antibody Electrostatics
Net charge Z(pH) and isoelectric point — T-20 & Ibalizumab
Why Subcutaneous Only?
At plasma pH 7.4, T-20 carries a large negative charge combined with MW 4,492 g/mol and logP ≈ −14.7. Passive membrane crossing is essentially zero → must be administered SC twice daily (90 mg).
Ionisable Residues
| Residue | Count | pKa | Type |
|---|
Shore Applicability
mAbs are large biologics (~150 kDa) with complex quaternary structure. The Shore model (designed for small-molecule passive diffusion) is not applicable. Ibalizumab is administered IV every 2 weeks (2,000 mg loading, then 800 mg maintenance).