Good old reliable milk. New research found that when it's combined with particular oral drugs, milk significantly improves their absorption by the body. It’s the latest in a series of studies showing that milk is a highly effective drug-delivery vehicle.
For something that many of us take for granted, milk has turned out to be incredibly valuable in the world of health and medicine. Over the years, New Atlas has reported on cows that produce human breast milk, HIV-inhibiting milk, or milk containing human insulin. But what’s become increasingly clear to scientists is that milk’s composition makes it an effective drug delivery system.
A new Monash University-led study found that adding both human and cow’s milk significantly improved the effectiveness of certain oral drugs. It’s the latest in a series of studies in which the researchers have investigated milk as a vehicle for improving drug delivery.
“Through our research over the years, we’ve consistently been able to demonstrate the way in which certain medicines are able to ‘piggyback’ with the milk, which our body treats like food and digests,” said Ben Boyd, a professor in the Monash Institute of Pharmaceutical Sciences (MIPS) and the study’s corresponding author. “Through this process, the milk and drug are absorbed, thereby enhancing the effectiveness of the drug.”
The term ‘bioavailability’ refers to how much of a drug actually reaches the bloodstream. Oral bioavailability, the bioavailability of drugs that are swallowed or otherwise delivered into the stomach, is affected by several factors, including the pH of the stomach and small intestine and enzymes and metabolism in the gastrointestinal (GI) tract. Therefore, the key to maximizing bioavailability is a drug’s formulation, which affects how well it is absorbed, distributed, and utilized by the body.
Many drugs are poorly water-soluble and lipophilic (fat-loving), and both pose challenges to bioavailability. As you’re probably aware, the human body, including the GI tract, is mostly water, so if a drug doesn’t dissolve well in water, its absorption into the bloodstream will be incomplete. Lipophilic drugs need fat for proper dissolution and absorption (which is why your pharmacist might tell you to take a particular medication with food).
This is where milk comes in handy. Because of their typical fat content, milk products can be considered a lipid-based formulation capable of enhancing the solubility of lipophilic drugs. Research has also shown that when poorly water-soluble drugs are combined with human or cow’s milk, digestion of the milk increases drug solubility. Moreover, milk is widely available, low-cost, and generally well-tolerated.
For the present study, the researchers focused on infants and the drug clofazimine. Traditionally, clofazimine has been used to treat leprosy and tuberculosis. Though, it has more recently been used to treat cryptosporidiosis, a parasitic infection that is a common cause of death in children under five in low- and middle-income countries. Clofazimine is extremely lipophilic, limiting its absorption when taken orally. To counter this, manufacturers house the drug in a soft-gel capsule; unfortunately, infants can’t swallow capsules. So, the researchers investigated whether combining the drug with milk would improve its bioavailability.
Neonatal piglets were randomly assigned to receive a dose of clofazimine dissolved in human milk, cow’s milk, or water, administered via a feeding tube passed through the mouth into the stomach. The researchers found that, compared to water, the bioavailability of clofazimine was significantly higher when administered in both human and bovine milk: 154% and 175%, respectively.
“Poorly soluble medicines such as clofazimine do not dissolve well in the stomach after administration and therefore developing age-appropriate formulations which are both safe and effective is challenging,” said the study’s lead author, MIPS PhD candidate Ellie Ponsonby-Thomas. “We know from previous studies that formulations aimed at infants involving milk-based vehicles can help medicines dissolve in the stomach, so we were excited to see this also applies to the administration of clofazimine.”
This study’s findings validate the researchers’ previous studies. In 2020, they were awarded a Eureka Prize for their work, supported by the Gates Foundation, showing that the solubility of two antimalarial drugs could be enhanced using milk. That research was published in Molecular Pharmaceutics. The study published in 2022 in Pharmaceutics found that dissolving praziquantel, a poorly water-soluble drug used to treat parasitic worm infections, in cow’s milk increased its solubility. Then, their 2024 study, published in the International Journal of Pharmaceutics, showed a two-fold increase in the oral bioavailability of cannabidiol (CBD) given in cow’s milk to infants. CBD is increasingly being used in epileptic pediatric patients to treat psychological issues and difficulties with performing daily tasks such as learning, socializing, and exercising.
However, there is still work to do. Although this collection of studies makes it clear that the effectiveness of important drugs is enhanced by milk, there are practical barriers to overcome, such as limited access to refrigeration in low- and middle-income countries and variations in milk quality.
“Naturally derived milk presents many hurdles in developing countries, which means that its implementation as an FDA-approved ingredient in medicines is difficult,” said Boyd. “Therefore, finding a way to develop milk-based vehicles as low-cost, infant-friendly formulations, which are highly regulated in a food context, could provide alternative solutions for treating prevalent diseases in low- and middle-income countries.”
The human breast milk used in the present study was donated by parents to the Australian Red Cross Lifeblood organization’s milk bank.
The study was published in the European Journal of Pharmaceutics and Biopharmaceutics.
Source: Monash University
