A nationwide shortage of stimulant medications used to treat attention-deficit hyperactivity disorder (ADHD) may be rooted less in prescribing practices or federal production quotas than in global supply chain disruptions, according to an analysis published late last week in JAMA Health Forum.
The study, led by researchers from Yale University, examined potential causes of the US stimulant shortage in 2022 and 2023, when many patients reported difficulty filling their prescriptions.
Public debate has often focused on rising diagnoses, expanded telehealth prescribing, and Drug Enforcement Administration (DEA) production limits as causes for the shortage, but the new findings suggest those explanations are incomplete—and highlight how vulnerable US pharmaceutical manufacturing is to global supply chain disruptions.
One-third of stimulants for US made in single facility
ADHD is common among US adults, with an estimated 15.5 million (6% of adults) reporting a diagnosis in 2023. Roughly one-third of those adults took stimulant medications that year, but getting access to the drugs was a challenge: More than 70% reported difficulty filling their prescriptions during the shortage.
Although the analysis looked primarily at the import of amphetamine, it also examined the import of two other stimulants, lisdexamfetamine and methylphenidate, because the United States experienced a shortage of those drugs starting in July 2023. Together, the three drugs account for over 90% of ADHD stimulant prescriptions.
More than 70% reported difficulty filling their prescriptions during the shortage.
“Sharp, simultaneous production cutbacks across several medium-sized and smaller manufacturers in late 2022 and early 2023 coincided with a steep contraction in US imports of raw amphetamines and more modest declines in phenylacetone, a key [stimulant] precursor,” the authors write. This drop in imports points to “what appears to be a supply chain failure.”
The supply chain disruption originated in the European Union, according to the analysis, and supply chain vulnerability likely arose from the degree of concentration among facilities producing amphetamines for the US market. “One study found that 33.7% of generic APIs [active pharmaceutical ingredients] for the US market in 2020 and 2021 were produced by a single facility, and another 30.4% by only 2 or 3 facilities,” they write.
Additional studies should focus on production concentration as a source of supply chain disruption, argue the authors. “Future research should aim to identify APIs supplied to the US market—whether they are produced domestically or abroad—by fewer than 4 or 5 facilities because these may represent the most vulnerable points in the pharmaceutical supply chain,” they write.
Drop in imports led to unmet demand
Debate about the causes of the shortage has been ongoing. Some experts have attributed it to increased prescribing, particularly during the COVID-19 pandemic, when telehealth expanded access to ADHD diagnosis and treatment. Others have pointed to the DEA’s quota system, which caps the amount of controlled substances manufacturers can produce.
But the study suggests that those factors alone cannot explain the shortage, noting that, collectively, drug manufacturers met only 70% of their production quotas in 2022. “It is likely that the abrupt drop in US imports of the active ingredient and the simultaneous but modest drop in the imports of its precursor in 2022, rather than DEA quotas, made it impossible for at least some manufacturers to meet demand,” they write.
The authors say addressing the ADHD stimulant shortage will require policies that go beyond regulating prescribing practices or quotas. Strengthening domestic manufacturing capacity and diversifying sources of APIs could help reduce the risk of future disruptions.