Can an Old, Inexpensive Drug Protect a Newborn's Kidneys After a Difficult Birth?

A 2024 study tested a single early dose of aminophylline in babies deprived of oxygen at birth, and found it did not prevent kidney injury

When a baby is severely deprived of oxygen around the time of birth, a condition doctors call perinatal asphyxia, the kidneys are among the first organs to suffer, and many of these newborns develop kidney injury in their first days of life. A 2024 clinical trial from Eastern India tested whether a single early dose of a cheap, widely available medicine called aminophylline could protect those kidneys. The answer was disappointing but useful: the drug slightly increased how much the babies urinated, but it did not actually lower the number who developed kidney injury, and it did not improve survival [1].

Why This Question Matters

A baby's kidneys quietly do enormous work. They clean waste from the blood and keep the body's water, salt, and minerals in careful balance. During a difficult birth in which oxygen and blood flow are interrupted, the kidneys can be injured much like a muscle starved of blood, a problem doctors call acute kidney injury. When the kidneys stumble, fluid and waste products build up, salts drift out of their normal range, and every other part of caring for a critically ill newborn, from feeding to breathing support to dosing other medicines, becomes more delicate and more dangerous.

The problem is also enormous in scale. Perinatal asphyxia is one of the leading causes of newborn death around the world, and its burden is far from evenly shared. It falls most heavily on countries where hospitals have the fewest resources, where continuous monitoring during labour and advanced newborn intensive care are often unavailable [2], [3]. A safe, low-cost medicine that could shield the kidneys would be most valuable in exactly those settings, which is precisely why researchers have returned to this question again and again over more than two decades. A treatment that is expensive or complicated helps only a fraction of the babies who need it; one that is cheap and simple could, in principle, help almost anyone. In the sickest babies, kidney injury is common and is linked to longer hospital stays and worse outcomes, so finding a way to prevent it has obvious appeal [4].

The Story Behind the Drug

The idea behind aminophylline is genuinely elegant, which is part of why it has been so hard to let go of. When the kidney runs short of oxygen, it releases a natural chemical called adenosine. Adenosine tightens the tiny blood vessels that feed the kidney's microscopic filters, choking off blood flow at the very moment the kidney can least afford it. Aminophylline, an old and familiar drug also used to help premature babies remember to breathe, blocks adenosine. In theory, blocking adenosine should relax those vessels, restore blood flow, and keep the filters working [5]. It is the kind of clean, logical mechanism that makes both scientists and clinicians want it to be true.

Because the idea made so much sense, several small studies in the late 1990s and early 2000s put it to the test. Some of them, including trials from Argentina, Kashmir, and Egypt, reported encouraging results and suggested that a single early dose helped protect the kidneys [6], [7], [8]. Later on, researchers gathered these small studies together and analysed them as a group, and those combined reviews also leaned cautiously positive. But the same reviewers were careful to add an important warning: the individual studies were small, they were run in different ways, they measured kidney injury using different definitions, and their results did not always agree with one another [9]. This left families and doctors in an uncomfortable middle ground for years: a medicine that seemed promising, that was cheap and available, but that had never been proven well enough to become an accepted, standard treatment. The 2024 trial was designed to look at the question again, carefully, in the everyday conditions of a real hospital.

What the Researchers Did and Found

The researchers studied 81 full-term babies born with severe asphyxia at a teaching hospital in West Bengal, India, between 2020 and 2021 [1]. To make the comparison fair, they used a random process, essentially the flip of a coin, to decide which babies received the drug. Forty-one babies were given a single dose of aminophylline into a vein within the first hour of life, on top of all the usual care, while 40 babies received the usual care alone. The medical team then watched each baby closely for five days, carefully measuring how much urine each one made and checking a blood marker of kidney function called creatinine every single day. Creatinine is a waste product that healthy kidneys clear from the blood; when it rises, it is a signal that the kidneys are not keeping up.

The results were clear. Kidney injury occurred in about 24 percent of the babies who received aminophylline and about 35 percent of those who did not. At first glance that gap looks meaningful, and it is easy to want to believe the drug made the difference. But the number of babies in the study was small, and a difference of that size could easily have arisen purely by chance. When researchers ran the proper statistical tests, the difference did not hold up as a real effect. Just as tellingly, the blood test of kidney function looked essentially the same in both groups on every day of the study. The babies who received the drug did urinate a little more, especially on the second and third days, but because their kidney blood test did not improve, the doctors concluded that the extra urine was not actually a sign of healthier kidneys, only of the drug's mild water-flushing effect. Survival was similar in both groups, and, if anything, the babies who received the drug stayed in the hospital slightly longer rather than shorter.

There was one further note of caution worth understanding. The babies who received aminophylline had somewhat more brain-related problems, including seizures, brain swelling, and bleeding in the brain. The numbers were small and did not reach the level scientists would call a proven effect, and much of it could simply reflect how severely ill these particular babies were to begin with. Even so, aminophylline is known to be able to make seizures more likely in some circumstances, so this is a signal the researchers specifically flagged as something to watch carefully in future work.

What This Means for Families

If your baby has been through a difficult, oxygen-deprived birth, the honest message from this study is reassuring precisely because it is clear. There is not yet a proven medicine that prevents kidney injury after severe asphyxia, and, based on the best current evidence, aminophylline is not that medicine. That may sound discouraging, but it is genuinely helpful to know, because it means families and clinicians can focus their energy on what does work. What truly helps these babies is excellent supportive care: careful attention to fluid balance, avoiding other medicines that can add stress to the kidneys, supporting blood pressure and breathing, and giving the kidneys the time they need to recover, which, encouragingly, they very often do. Newborn kidneys have a real capacity to heal once the crisis has passed.

The authors of this study were candid about their conclusion, recommending that aminophylline be used only within research studies for this purpose rather than as a routine treatment [1]. This is medicine working the way it should. A promising idea was tested rigorously and honestly, and the researchers were willing to report that it did not work as they had hoped rather than continuing a practice out of habit or wishful thinking. Every time a treatment that does not help is set aside, babies are spared unnecessary medicines and their possible side effects.

It is also worth knowing one important detail about where this study was done. The hospital did not have the ability to offer cooling therapy, a treatment now used in many parts of the world that gently lowers a baby's body temperature to protect the brain after oxygen deprivation. How aminophylline behaves in babies who are being cooled is a different and still-open question that researchers are actively studying, so these results speak most directly to hospitals where cooling is not available [10].

What Researchers Are Working On Next

This trial was relatively small and was carried out at a single hospital, so it could not deliver the final word. What it could do, and did, was show that any benefit from the drug, if one exists at all, is smaller than earlier studies had hoped, and that it may come with real risks. Earlier work had already pointed in mixed directions, with some studies finding the same temporary bump in urine output but no lasting protection for the kidneys, exactly as this trial found [11].

The next step that scientists are calling for is a much larger study run across many hospitals at once, comparing the drug against a dummy treatment so that neither families nor doctors know who received which, including babies who are being cooled, measuring the level of the drug in each baby's blood to keep it safe, and following the children for years afterward to check on both their kidney health and their overall development. Until those bigger and more definitive studies are done, families can take real comfort in knowing that careful, attentive newborn care remains the single most important thing, and that researchers are continuing to search, honestly and rigorously, for anything that can do better.

References

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  2. Ou Z, Yu D, Liang Y, et al. Global trends in incidence and death of neonatal disorders and its specific causes in 204 countries/territories during 1990-2019. BMC Public Health. 2022;22:360. doi:10.1186/s12889-022-12765-1 ↩
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  8. Bakr AF. Prophylactic theophylline to prevent renal dysfunction in newborns exposed to perinatal asphyxia—a study in a developing country. Pediatr Nephrol. 2005;20(9):1249-1252. doi:10.1007/s00467-005-1980-z ↩
  9. Bhatt GC, Gogia P, Bitzan M, et al. Theophylline and aminophylline for prevention of acute kidney injury in neonates and children: a systematic review. Arch Dis Child. 2019;104(7):670-679. doi:10.1136/archdischild-2018-315805 ↩
  10. Chock VY, Cho SH, Frymoyer A. Aminophylline for renal protection in neonatal hypoxic-ischemic encephalopathy in the era of therapeutic hypothermia. Pediatr Res. 2021;89(4):974-980. doi:10.1038/s41390-020-0999-y ↩
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