For healthcare professionals. Compounded preparations are dispensed on a doctor’s prescription.
Short answer: Tongkat ali (Eurycoma longifolia) quassinoids have low bioavailability, which a 2017 study attributes to high aqueous solubility and low lipid membrane permeability (PMID 28948658). A lipid-based solid dispersion of a standardised extract has been prepared and given orally to rats (PMID 28948658). The studies below are laboratory and animal work, and they do not show an effect in people.
The formulation problem
A 2017 study that formulated a standardised Eurycoma longifolia root extract (in vitro and rat work) states, as background, that its two major quassinoids “possess low bioavailability because of high aqueous solubility and low lipid membrane permeability”. It adds that P-glycoprotein efflux and presystemic metabolism were other possible barriers (Phytotherapy Research, 2017; PMID 28948658). A 2018 in vitro, rat and mouse study reports that eurycomanone “is not readily absorbed across biological membranes”, although once absorbed “the compound is not easily metabolised” (Pharmaceutics, 2018; PMID 29997335).
These statements describe the active’s pharmaceutical behaviour. They are not evidence of a clinical effect. For a prescriber, the formulation question is whether a capsule can carry the extract’s active constituents past the barriers the studies describe, and that is a question the studies below address only in animals and in vitro.
What the formulation research did and found
Rat oral study of a lipid-based solid dispersion (PMID 28948658)
The study formulated a standardised extract, with an optimised mixture of emulsifiers, as a lipid-based solid dispersion, and gave it orally to rats (2017; PMID 28948658). The abstract reports that P-glycoprotein efflux inhibitors produced no significant in vitro ileal absorption change, and that incubation with rat liver homogenates produced no concentration change or secondary metabolite formation, “suggesting that P-gp-mediated efflux and presystemic metabolism were not limiting their bioavailability” (PMID 28948658). This is an animal and in vitro finding. It does not establish the absorption of a capsule in a person.
Rat and mouse pharmacokinetics of eurycomanone (PMID 29997335)
This study examined the solubility, chemical stability, permeability and pharmacokinetics of eurycomanone, in vitro and in rats and mice. The abstract reports a bioavailability of 11.8% in rats and 54.9% in mice for eurycomanone in its compound form, and states that these pharmacokinetic parameters “cannot be directly extrapolated to humans” (PMID 29997335). The same abstract describes the compound as not readily absorbed across biological membranes, and as stable once absorbed (PMID 29997335).
Study table
| Design | Model | Delivery system | Finding as reported | PMID |
|---|---|---|---|---|
| Formulation with oral dosing, efflux and metabolism tests | Rats (oral); in vitro ileal and liver homogenate tests | Lipid-based solid dispersion of a standardised extract with emulsifiers | P-gp efflux and presystemic metabolism “not limiting their bioavailability” in the study’s tests | 28948658 |
| Solubility, permeability, stability and pharmacokinetic study | In vitro (Caco-2 cells, plasma and liver microsomes); rats and mice | Pure eurycomanone and a standardised water extract | Not readily absorbed across biological membranes; bioavailability of pure eurycomanone 11.8% (rats) and 54.9% (mice); cannot be directly extrapolated to humans | 29997335 |
How to read the bioavailability records
The two studies answer different questions, and they should be read separately. The 2017 study asks why the quassinoids are poorly absorbed, and it tests efflux and metabolism in vitro and in rats after an oral lipid-based dispersion (PMID 28948658). The 2018 study measures the pharmacokinetics of one compound, eurycomanone, in rats and mice, and also evaluates the pharmacokinetic parameters of a standardised water extract of E. longifolia in rats (PMID 29997335). It states that these parameters cannot be directly extrapolated to humans. Neither record reports a clinical outcome in people. A prescriber who reads the rat bioavailability figure should not treat it as a human exposure value.
What is still unknown
The studies do not describe an oral tongkat ali capsule in people. Whether a capsule formulation changes human exposure to the quassinoids is not established by these records. No human pharmacokinetic data are reported in the cited records. The 2018 study measured stability in liver microsomes from several species, including human, in vitro only, and its rodent pharmacokinetic parameters cannot be directly extrapolated to humans (PMID 29997335). The extract standard and the strength per capsule that a prescriber would specify are also not established here.
How this approach could be prepared at Lynnity
A capsule is one of the non-sterile forms Lynnity prepares, and capsules may be prepared in a liposomal or an ordinary form, to a prescriber’s specification for one named patient (see the liposomal compounding overview). For a tongkat ali capsule, the prescription specifies the extract, the strength per capsule and the directions. The preparation is made under Good Compounding Practice (GCP). This describes what a prescription may request. It is not a statement that a particular preparation has been made or tested.
Where the evidence stops
Both records examine the active’s behaviour in laboratory and rodent models. The rat solid-dispersion study is not a comparison with a commercial capsule, and the pharmacokinetic study does not include a capsule. Neither record establishes the dose a person would need, the safety of an oral capsule over a course, or any effect on a clinical outcome. A prescriber weighing this option should treat the findings as formulation evidence, and set the clinical question separately.
How to prescribe
A tongkat ali capsule is prepared only on a registered doctor’s prescription, for one named patient, under Good Compounding Practice (GCP). The prescription must state:
- the active, Eurycoma longifolia (tongkat ali) extract, with the extract standard the prescriber specifies;
- the strength per capsule;
- the form, a capsule, and whether it is prepared as a liposomal or an ordinary capsule;
- the quantity and the directions for use, with the review date.
Send the signed prescription through the contact page at https://www.lynnitypharma.com/contact-us/.
Related reading: the liposomal compounding pharmacy guide and custom compounded medication in Malaysia. Laboratory standards are described on the GCP laboratory page.
Reviewed by Vitthia Rama Murti, RPh (RPh 15632).
Frequently asked questions
Why is tongkat ali difficult to formulate for oral delivery?
The quassinoids are described as having low bioavailability because of high aqueous solubility and low lipid membrane permeability (PMID 28948658). A 2018 in vitro, rat and mouse study reports that eurycomanone is not readily absorbed across biological membranes, and that its bioavailability for the pure compound differed between rats and mice (PMID 29997335). These are pharmaceutical findings about the active, not clinical outcomes.
Do these studies show that a tongkat ali capsule works in people?
No. The studies are in vitro or in rats and mice. The abstract of the rodent pharmacokinetic study states that its parameters cannot be directly extrapolated to humans (PMID 29997335). The studies do not show an effect in people, and they do not support a clinical claim for a capsule.
What did the rat study of the solid dispersion examine?
It formulated a standardised extract as a lipid-based solid dispersion with emulsifiers and gave it orally to rats (PMID 28948658). The abstract reports that P-gp efflux and presystemic metabolism were not limiting the quassinoids’ bioavailability in its tests (PMID 28948658). These are animal and in vitro findings.
What must a tongkat ali capsule prescription state?
It must state the extract and its standard, the strength per capsule, the form (a capsule), the quantity and the directions for one named patient. The preparation is made on a registered doctor’s prescription under Good Compounding Practice (GCP).