The median incubation period is 10 days (range 2 - 43 days).2,14 The disease develops in two phases; initially, patients experience a period of flu-like symptoms with a median duration of 3.9 days (range, 3.5 to 4.4 days).12 Nonspecific symptoms reported in this phase include fever, malaise, sweats, cough, dyspnea, altered mental state, nausea and vomiting, headache, and muscle aches.1 A transition to severe illness follows abruptly, with high fever, dyspnea, diaphoresis, and shock.2
Chest imaging reveals widening of the mediastinum, mediastinal lymphadenopathy, infiltrates, and pleural effusions.1
Because the progression from non-specific to severe, life-threatening symptoms is rapid; the treatment window for inhalational anthrax is brief.
ANTHIM® (obiltoxaximab) is indicated in adult and pediatric patients for the treatment of inhalational anthrax due to Bacillus anthracis in combination with appropriate antibacterial drugs. ANTHIM is indicated for prophylaxis of inhalational anthrax due to B. anthracis when alternative therapies are not available or are not appropriate.
WARNING: HYPERSENSITIVITY and ANAPHYLAXIS
Hypersensitivity and anaphylaxis have been reported during the intravenous infusion of ANTHIM. Due to the risk of hypersensitivity and anaphylaxis, ANTHIM should be administered in monitored settings by personnel trained and equipped to manage anaphylaxis. Monitor individuals who receive ANTHIM closely for signs and symptoms of hypersensitivity reactions throughout the infusion and for a period of time after administration. Stop ANTHIM infusion immediately and treat appropriately if hypersensitivity or anaphylaxis occurs.
Hypersensitivity reactions were the most common adverse reactions in the safety trials of ANTHIM, occurring in 34/320 healthy subjects (10.6%). Three (0.9%) cases of anaphylaxis occurred during or immediately after the infusion. In clinical trials, manifestations of anaphylaxis were rash/urticaria, cough, dyspnea, cyanosis, postural dizziness and chest discomfort. ANTHIM infusion was discontinued in 8 (2.5%) subjects due to hypersensitivity or anaphylaxis. The adverse reactions reported in these 8 subjects included urticaria, rash, cough, pruritus, dizziness, throat irritation, dysphonia, dyspnea and chest discomfort. The remaining subjects with hypersensitivity had predominantly skin-related symptoms such as pruritus and rash, and 6 subjects reported cough.
Premedication with diphenhydramine is recommended prior to administration of ANTHIM. Diphenhydramine premedication does not prevent anaphylaxis, and may mask or delay onset of symptoms of hypersensitivity.
The safety of ANTHIM has been studied only in healthy volunteers. It has not been studied in patients with inhalational anthrax. The most frequently reported adverse reactions (occurred in >1.5% of healthy subjects) were headache, pruritus, infections of the upper respiratory tract, cough, vessel puncture site bruise, infusion site swelling, urticaria, nasal congestion, infusion site pain, and pain in extremity.
No adequate and well-controlled studies in pregnant women were conducted. Because animal reproduction studies are not always predictive of human response, ANTHIM should be used during pregnancy only if clearly needed.
There have been no studies of the safety or PK of ANTHIM in the pediatric population.