Women on Preventive Heme Arginate Have Fewer Acute Attacks
Women with acute intermittent porphyria (AIP) receiving once-weekly preventive treatment with heme arginate — given as an intravenous or into-the-vein infusion — had fewer and less severe attacks, a small study found.
Indeed, these AIP patients saw a reduction in acute attacks by more than 80% with the use of the prophylactic, or preventive heme treatment.
These findings suggest that heme arginate could provide “a safe and effective strategy for managing patients with AIP,” the researchers wrote.
The study, “Prophylactic heme arginate infusion for acute intermittent porphyria,” was published in the journal Frontiers in Pharmacology by a team of researchers in Taiwan.
Porphyrias encompass a group of disorders resulting from disruptions in the signaling cascade leading to the production of heme — a molecule that is necessary for oxygen transport in living cells.
Symptoms of acute porphyria emerge suddenly and may include pain in the abdomen or in other parts of the body, constipation or vomiting, and changes in mental status lasting several hours to days.
In women, these acute attacks often coincide with the latter phase of the menstrual cycle, which means they occur at predictable times every one or two months.
“Typically, acute porphyric attacks last no longer than 1–2 weeks and can be treated efficiently with 3–5 days of intravenous heme therapy,” the researchers wrote.
Heme is available in the U.S. as hematin. In Taiwan, where the study was conducted, it is available as heme arginate. It can be given shortly before the expected onset of an attack, or once per week to prevent acute attacks.
Now, the team wanted to see how effective and safe long-term preventive treatment with heme arginate was at reducing the number and severity of acute attacks in patients with AIP.
Their study included five women who were experiencing more than nine acute attacks per year. The patients’ ages ranged from 21 to 51 at the beginning of the study.
All five women had disease-causing mutations in the gene providing instructions to make porphobilinogen deaminase, an enzyme involved in the production of heme.
They received preventive treatment with heme arginate, given at three milligrams per kilogram of body weight once weekly, for an average of 8.57 years (ranging from 2.58 to 14.64 years).
In the year prior to starting preventive treatment, the women had an average of 11.82 acute attacks and had used a mean of 2.81 doses of heme arginate to treat each attack.
After preventive treatment, the average number of acute attacks was reduced to 2.23 and the average number of doses of heme arginate per attack was reduced to 1.39, indicating less severe attacks.
In two women, the frequency and severity of acute attacks were further reduced during and after menopause, suggesting that preventive treatment with heme arginate may be effective across all stages of a woman’s life.
“Common complications during the course of treatment were venous access issues (infection, thrombosis) that were managed easily,” the researchers wrote. Of note, venous thrombosis occurs when a blood clot blocks a vein that carries blood from the body back to the heart.
No other complications occurred during long-term use of heme arginate, and liver and kidney function remained stable.
Heme arginate “given regularly and managed properly provided substantial and long-term clinical benefit to carefully-selected patients,” the researchers concluded. “Both the frequency and the severity of porphyric attacks were reduced.”