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Lipophilic efficiency

Lipophilic efficiency is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lipophilic efficiency rather than just read about it. In short: Lipophilic efficiency (LiPE), sometimes referred to as ligand-lipophilicity efficiency (LLE) is a parameter used in drug design and drug discovery to evaluate the quality of research compounds, linking potency and lipophilicity in an attempt to estimate druglikeness. For a given compound LiPE is defined as the pIC50 (or pEC50) of interest minus the LogP of the compound.

Lipophilic efficiency — main illustration
Lipophilic efficiency — illustration

Key takeaways

  • Lipophilic efficiency belongs to chemistry; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Lipophilic efficiency to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Lipophilic efficiency from memory before moving on to harder problems.

Reference excerpt

Lipophilic efficiency (LiPE), sometimes referred to as ligand-lipophilicity efficiency (LLE) is a parameter used in drug design and drug discovery to evaluate the quality of research compounds, linking potency and lipophilicity in an attempt to estimate druglikeness. For a given compound LiPE is defined as the pIC50 (or pEC50) of interest minus the LogP of the compound.

LiPE = pIC 50 − log ⁡ P {\displaystyle {\ce {LiPE}}={\ce {pIC50}}-\log P}

In practice, calculated values such as cLogP or calculated LogD are often used instead of the measured LogP or LogD. LiPE is used to compare compounds of different potencies (pIC50s) and lipophilicities (LogP). High potency (high value of pIC50) is a desirable attribute in drug candidates, as it reduces the risk of non-specific, off-target pharmacology at a given concentration. When associated with low clearance, high potency also allows for low total dose, which lowers the risk of idiosyncratic drug reaction. On the other hand, LogP is an estimate of a compound's overall lipophilicity, a value that influence its behavior in a range of biological processes relevant to a drug discovery, such as solubility, permeability through biological membranes, hepatic clearance, lack of selectivity and non-specific toxicity. For oral drugs, a LogP value comprised between 2 and 3 is often considered optimal to achieve a compromise between permeability and first-pass clearance. LiPE allows capturing both values in a single parameter, and empirical evidence suggest that quality drug candidates have a high LiPE (>6); this value corresponds to a compound with a pIC50 of 8 and a LogP of 2. Plotting LogP against pIC50 for a range of compounds allows ranking series and individual compounds. An alternative equation uses the logarithm of the ratio of potency (measured as binding energy) and the partition coefficient to compute a lipophilic ligand efficiency index (LE) with a different scale.

LElipo = log ⁡ ( − Δ G P ) {\displaystyle {\ce {LElipo}}=\log \left({\frac {-\Delta G}{P}}\right)}

The following review discusses LipE in the context of other compound efficiency metrics.

References

Illustrations

Lipophilic efficiency: A plot of LogP vs pIC50 for 2 series of compounds (series 1: green dots, series 2: blue dots). Diagonal lines represents areas of equal LiPE. Analysis of this LiPE plot shows that series 1 includes many compounds with a high LiPE, and thus may represent a better lead series for further optimization.
A plot of LogP vs pIC50 for 2 series of compounds (series 1: green dots, series 2: blue dots). Diagonal lines represents areas of equal LiPE. Analysis of this LiPE plot shows that series 1 includes many compounds with a high LiPE, and thus may represent a better lead series for further optimization.

Worked examples

Example 1 — a first encounter with Lipophilic efficiency

Start with the simplest possible case. Write down what Lipophilic efficiency claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lipophilic efficiency before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lipophilic efficiency ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lipophilic efficiency

In research
Lipophilic efficiency appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Lipophilic efficiency in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Lipophilic efficiency is common in secondary-school and first-year university syllabi. It links to neighbouring topics Drug discovery, Medicinal chemistry, Pharmacokinetics, so understanding it makes those chapters shorter.
In everyday life
Look for Lipophilic efficiency outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Lipophilic efficiency in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Lipophilic efficiency means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Lipophilic efficiency out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lipophilic efficiency in simple terms?

Lipophilic efficiency (LiPE), sometimes referred to as ligand-lipophilicity efficiency (LLE) is a parameter used in drug design and drug discovery to evaluate the quality of research compounds, linking potency and lipophilicity in an attempt to estimate druglikeness. For a given compound LiPE is de…

Why does Lipophilic efficiency matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lipophilic efficiency?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lipophilic efficiency.

Tags

  • Drug discovery
  • Medicinal chemistry
  • Pharmacokinetics

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