# Presentation: 630120

## Radiological Terrorism:Medical Response to Mass CasualtiesPart II

**Jeffrey B. Nemhauser, MD**
**Medical Officer**
**Radiation Studies Branch**
**National Center for Environmental Health**
**Centers for Disease Control and Prevention**
** **

## TriageKey Concepts

**Victim categories following radiological/nuclear incident**
**(Possibly) exposed**
**Injured and Uninjured**
**Unexposed**
**Injured and Uninjured**

**Notes:**
In the aftermath of a radiological or nuclear incident, clinicians should expect large numbers of physically and psychologically injured individuals to present to the emergency department – this includes people not in close physical proximity to the event.

For the purposes of triage following such a disaster, individuals may be divided into 1 of 4 categories:
Those who are injured and possibly exposed to radiation
Those who are not injured but who may be exposed to radiation
Those who are injured but not exposed to radiation
And, finally, those who are neither injured nor exposed to radiation

Since emergency department physicians are well-trained to handle patients that fall into the latter 2 categories, this lecture will focus on the management of persons who have suspected or confirmed radiation exposure.

## TriageKey Concepts

**Combined Injury**
**Physical, thermal, and/or chemical trauma**
**Radiation exposure in doses sufficient to threaten overall survival / recovery**

**Notes:**
Individuals who have been exposed to radiation and who have sustained physical trauma are said to have a combined injury.

Combined injury is defined as physical, thermal, and/or chemical trauma combined with radiation exposure at a dose sufficient to threaten overall survival or recovery.

Thus, management of any traumatic, chemical, or thermal injury can be complicated by the added presence of radiation injuries.

## TriageKey Concepts

**Radiation Exposure (Irradiation)**
**High doses – combined with trauma – can cause serious or life-threatening illness**
**At very high doses, irradiation *****by itself***** may cause early, life-threatening adverse health effects**

**Notes:**
Radiation exposure – also referred to as “irradiation” – can cause serious or life-threatening illness.

At sufficiently high doses, irradiation by itself may precipitate the onset of early, life-threatening adverse health effects.

This occurs, however, only at levels of exposure likely to be seen in instances like the detonation of a nuclear bomb or an improvised nuclear device.

## TriageKey Concepts

**Triage during first 24 hours**
**Consider irradiation**
**Treatment decisions based on**
**Adverse Health Effects**
**First 24–48 hours**
**Laboratory Test Results**
**History (medical and exposure)**
**Contamination Assessment**

**Notes:**
Given that radiation exposure – when combined with physical, thermal, and/or chemical trauma – can threaten overall survival or recovery, triage and treatment decisions must include consideration of the effects of radiation exposure on an individual.

Treatment decisions should be based on the following four criteria:
physical findings – these include the characteristic adverse health effects known to be caused by radiation exposure
laboratory test results
history of the exposure event
And, a contamination assessment of the patient

Combined, these 4 factors can help guide the emergency department clinician in the proper management and treatment of a patient in a mass casualty situation, especially when resources may be limited.
I’m now going to spend a little time discussing how the presence of characteristic adverse health effects and certain laboratory test results can assist the clinician in the mass casualty management of victims of radiation exposure.

## Adverse Health EffectsAcute Radiation Syndrome (ARS)

**ARS caused by irradiation of whole body or significant portion thereof**
**Adverse health effects**
**Type, severity, and time to onset dependent on radiation dose (i.e., amount of energy deposited in the body)**

**Notes:**
“Adverse health effects due to radiation exposure” form one important set of clinical clues that the emergency department clinician can use to assist in triage of the Radiation Mass Casualty victim

These initial adverse health effects form one part of an illness known as Acute Radiation Syndrome or ARS.

ARS is caused by irradiation of the whole body or significant portions of it.

The type and severity of ARS health effects and the timing of their onset depend on the total amount of energy deposited in – or absorbed by – the body

This is known as the radiation dose

## Adverse Health EffectsAcute Radiation Syndrome (ARS)

**Three stages of ARS**
**Prodrome**
**Latent Period**
**Manifest Illness**

**Notes:**
All cases of ARS may be divided into 3 Stages
The prodrome
The latent period
The manifest illness stage

The prodrome is the stage most likely to be seen by the emergency department clinician and is the stage during which early triage and management decisions will be made.

Depending on the dose of exposure, clinicians in the emergency department may – or may not – witness the onset of the latent period and the manifest illness stages of ARS

## Adverse Health Effects Acute Radiation Syndrome: Prodrome

**Begins after exposure**
**Lasts 24–48 hours**
**Adverse health effects**
**Nausea/vomiting/diarrhea, fatigue, headache, parotitis, erythema, fever**

**Notes:**
The prodrome stage of ARS is the first stage of this illness and, for most radiation exposures, lasts approximately 24–48 hours.

Adverse health effects most commonly seen during the prodromal stage include nausea and vomiting, possibly diarrhea, fatigue, headache, salivary gland inflammation, erythema or redness to the skin, and fever.

By themselves, none of these adverse health effects should be considered life-threatening although fluid and electrolyte loss due to vomiting and diarrhea may become problematic

## Adverse Health Effects Acute Radiation Syndrome: Prodrome

**Prodromal adverse health effects**
**Onset occurs more rapidly with severe ARS than with mild ARS**
**Nausea and vomiting are hallmark**
**Time to emesis may be used as rough estimate of exposure and outcome**

**Notes:**
The prodrome of ARS is particularly helpful in the triage of patients with acute radiation exposure

During this stage, the onset of adverse health effects occurs more rapidly with more severe forms of ARS than with the more mild forms

Nausea and vomiting, in particular, are reliable indicators of acute radiation sickness

The time to emesis following an exposure is roughly correlated to the absorbed dose – as we shall see on the next slide

## Adverse Health Effects Acute Radiation Syndrome: Prodrome

**Estimation of severity of ARS following a single acute dose exposure**
**Onset of vomiting within 1-2 hours is highly suggestive of a poor prognosis**

| Vomiting Post Incident | Degree of ARS |
| --- | --- |
|  > 2 hours after | Mild |
| 1-2 hours | Moderate |
| < 1 hour | Severe |
| 10 – 30 minutes | Very Severe |
| < 10 minutes | Rapidly Lethal |

- Source: Berger, et al. [2002]. Hospital Triage in the First 24 Hours After a Nuclear or Radiological
- Disaster. REAC/TS Training Site. _[http://www.orau.gov/reacts](http://www.orau.gov/reacts)_

**Notes:**
The rapid onset of vomiting following a radiological or nuclear incident indicates a high dose of exposure and an increasingly poor prognosis

Conversely, vomiting occurring more than 2 hours after a possible exposure is indicative of a lower dose of exposure, a more mild course of ARS, and a better overall prognosis 

## Adverse Health Effects Acute Radiation Syndrome: Prodrome

| ARS Prodrome | Manifestation of Illness | Prognosis 
(without therapy) |
| --- | --- | --- |
| Mild | Slight decreases in blood counts | Almost certain survival |
| Mild to Moderate | Early signs of bone marrow damage | Highly probably survival |
| Moderate | Moderate to severe bone marrow damage | Probable survival |
| Severe | Severe bone marrow damage; slight GI damage | LD50 
(Within 3.5 – 6 weeks) |

- Source:  Ann Intern Med [2004] 140(12):1037-1051. _[http://www.annals.org](http://www.annals.org/)__ _

**Notes:**
This slide – and the one that follows – summarize the clinical findings characteristic of the final stage of ARS – and the prognosis for recovery – based on the ARS prodrome.

Simply put, as the time to disease onset shortens and severity of prodromal health effects worsen, the worse the prognosis bercomes

I’m not going to take the time to fully discuss these slides now but I encourage you to use them as references.

## Adverse Health EffectsAcute Radiation Syndrome: Prodrome

- Source:  Ann Intern Med [2004] 140(12):1037-1051. http://www.annals.org

| Prodrome | Manifestation of Illness | Prognosis 
(without therapy) |
| --- | --- | --- |
| Severe | Pancytopenia and moderate GI damage | Death probable
(Within 2 – 3 weeks) |
| Severe | Marked GI damage and  bone marrow damage; hypotension | Death probable
(Within 1 – 2.5 weeks) |
| Severe | Severe GI damage; pneumonitis;        altered mental status; cognitive dysfunction | Death certain
(Within 5 – 12 days) |
| Severe | Cerebrovascular collapse; fever; shock | Death certain
(Within 2 – 5 days) |

**Notes:**
In this slide, we see the worsening spectrum of disease.

In each case, vomiting occurs within 1–2 hours and possibly even sooner

In the bottom row, for example, a severe prodrome – characterized by the onset of vomiting (within minutes) and diarrhea – combined with CNS injury, fever, and shock – is indicative of certain death, usually within days

Using these clinical clues can provide clinicians with an estimate of injury and an indication of how best to allocate limited resources in the face of a mass casualty event

## Laboratory TestingAcute Radiation Syndrome: Prodrome

**Lymphocytes**
**Highly radiosensitive**
**Progressive decline in absolute lymphocyte counts provides early estimate of injury and outcome**
**Obtain baseline CBC with differential and repeat for 24–48 hrs.**

**Absolute Lymphocyte Count**

- Source:  Andrews, et al. [1965] Personal Dosimetry for Radiation Accidents. Vienna: International Atomic Energy Agency.

**Notes:**
Another tool available to emergency department clinicians to help aid triage decisions is a determination of the total lymphocyte count

Lymphocytes are among the most radiosensitive cells in the body

A progressive decline in absolute lymphocyte counts provides an early estimate of injury caused by an acute radiation exposure

This is seen in the graph on this slide – the Andrews nomogram

Victims of acute radiation exposure should have – as part of their workup – a complete blood count drawn at baseline. This should be repeated in 4–6 hours and then every 6–8 hours thereafter for 24–48 hours.

Results should be plotted and compared to the curves on this nomogram – rapid declines in absolute lymphocyte count indicate both a higher dose of exposure and a poorer likelihood for recovery

## TriageCombined Injury

| Conventional Trauma Triage Categories
(Without Radiation Exposure) | Changes in Expected Trauma Triage Categorization
 Following Whole-body Radiation Exposure
(Based on Time-of-Onset to Vomiting as Estimation of ARS Severity) |  |  |
| --- | --- | --- | --- |
|  | > 2 hours | 1 – 2 hours | < 1 hour |
|  | Mild | Moderate | Severe – Lethal |
| Delayed | Delayed | Variable* | Expectant |
| Immediate | Immediate | Immediate | Expectant |
| Minimal | Minimal | Minimal | Minimal  |
| Expectant | Expectant | Expectant | Expectant  |
| Absent | Outpatient monitoring | Outpatient monitoring with routine care or hospitalization as needed  |  |

- *Variability is dependent on the nature and extent of traumatic injury.
- Source:  Adapted from Ann Intern Med. [2004] 140:1037-1051. http://www.annals.org

**Notes:**
This slide now reintroduces the concept of Combined Injury discussed at the outset of the lecture.
This table illustrates the effect of radiation exposure on prognosis and outcome.
The left column indicates conventional trauma triage categories in the absence of radiation exposure.
At low whole-body doses of radiation exposure – as indicated by a more prolonged time to onset of vomiting – trauma triage categories remain same
However, at higher whole-body doses of radiation exposure, the trauma patient’s prognosis worsens – patients having combined injury and a severe-to-lethal whole-body dose exposure should be triaged as expectant

Radiation Mass Casualty events in which there are large volumes of patients having combined injury will test limited health care resources significantly and triage decisions will need to be made that consider long-term prognosis

## TriageWrap-Up

**Acute Radiation Syndrome**
**3 stages – Prodome is triage key**
**Clinical guides to victim triage**
**Time to prodrome onset (vomiting)**
**Total lymphocyte count**
**Combined injury generally means a worse prognosis**

**Notes:**
In summary, then, mass casualty patients following a radiological or nuclear incident may be triaged as either exposed or not exposed to radiation.
Triage of exposed individuals may be based on adverse health effects – specifically nausea and vomiting – that patients exhibit within the first 2 hours following exposure.
Time to onset of vomiting during this period of time – known as the prodromal period – serves as a marker of the severity of Acute Radiation Syndrome and an individual’s longer-term prognosis.
Measurement of the total lymphocyte count is another tool that should be used by clinicians to aid in decisions about patient management and resource utilization. Rapid depletion of lymphocytes over a relatively short period of time is indicative of severe illness and likely patient demise.

Trauma victims not having radiation exposure will be managed by emergency department teams as usual.
Trauma victims having radiation exposure have what is referred to as “Combined Injury” and, in general, will have a worse prognosis.

A more complete discussion of the management of Combined Injury will be presented in the next lecture.

## Radiological Terrorism Internal Contamination

**Time-dependent phenomenon**
**Related to physical properties of isotope**
**Incorporation can occur rapidly**

**Notes:**
The deposition of radioactive materials in the body – internal contamination – is a time-dependent phenomenon related to both the physical and chemical properties of the contaminant. 

Once internal contamination has occurred, the rate of radionuclide incorporation into target tissues can occur rapidly

Thus, time to treatment is critical

For treatment to be effective, it must be administered quickly in order to have the best chance at mitigating adverse health effects.

## Radiological Terrorism Internal Contamination: Diagnosis

**Exposure history**
**Potential for inhalation or ingestion**
**Open wounds containing shrapnel**
**Bioassay**
**Complete Blood Count**
**Urinalysis for radiation**

**Notes:**
Clinicians will need to rely on the basic tools of diagnosis – history, physical examination, and a couple of confirmatory laboratory studies to make a presumptive diagnosis of internal contamination

An exposure history can help identify the likelihood or potential for inhalation or ingestion of radionuclides following a radiation mass casualty event – these clues can help increase the clinician’s index of suspicion that internal contamination may have occurred.

On physical examination, the presence of open wounds containing shrapnel should certainly suggest the possibility of internal contamination.

Finally, a laboratory assessment can provide clues as to the likelihood of internal contamination.  A falling absolute lymphocyte count coupled with measured levels of radioactivity in a victim’s urine are strongly suggestive of internal contamination.

## Radiological Terrorism Internal Contamination: Treatment

**Treatment most effective when administered early**
**Decision to treat may be based on preliminary data**
**Block or decorporate *****and***** treat effects of exposure**

**Notes:**
Ultimately, treatment decisions may be based on a history that is only suggestive for exposure or on incomplete laboratory data

Nonetheless, for treatment to be most effective, it should be initiated early following radiation exposure and clinicians may be required to make decisions about whom to treat in the absence of complete or compelling evidence

Various treatment modalities are available – the most sophisticated are directed at preventing the incorporation of or removing radioactive isotopes from the body

However, two methods familiar to most physicians to prevent incorporation that can be used shortly after ingestion of a radionuclide include
Gastric lavage and Catharsis

In addition, effects of radiation exposure such a nausea and vomiting should also be treated

## Radiological Terrorism Internal Contamination: Treatment

**Anti-emetics as necessary**
**Ondansetron, granisetron, or other serotonin receptor antagonists**
**Anti-diarrheals**
**Loperamide hydrochloride, Lonox (diphenoxylate/atropine)**
**Replace fluids and electrolytes as necessary**

**Notes:**
Drugs to treat nausea, vomiting, and diarrhea should be used as necessary and fluid and electrolyte balance should be carefully monitored and aggressively treated.

PAUSE

I would now like to use the remainder of this lecture and the lecture to follow to introduce and begin the discussion of the pharmacotherapy of internal contamination.

The four agents to be discussed include:
Potassium Iodide or KI
Prussian Blue
DTPA
And the granulocyte colony stimulating factor, filgrastim.

## PharmacotherapyPotassium Iodide

**IOSATTM; ThyroSafeTM; Thyro-BlockTM**
**ThyroShieldTM solution for children**
**Orally administered radioactive iodine blocking agent**
**Prevents radioactive iodine uptake in thyroid gland by competing for binding sites**

**Notes:**
Potassium iodide – or KI – is an orally administered radioactive iodine blocking agent

KI is available as a variety of preparations, including an FDA-approved solution – for administration to children 

KI acts by blocking the incorporation of radioactive iodine into the thyroid gland by competing with the radioisotope for uptake binding sites

This agent should be administered as quickly as possible following a radiation mass casualty event in which there is a high likelihood of exposure to radioactive iodine

## PharmacotherapyPotassium Iodide

**Radioactive iodine release scenarios**
**Nuclear power plant incident**
**Detonation of improvised nuclear device**
**“****Dirty bomb” is unlikely source**

**Notes:**
Radiation mass casualty events in which the release of radioactive iodine is most likely include
Nuclear power plant incidents – for example, significant levels of radioactive iodine were released following the Chernobyl nuclear power plant explosion in 1986
Also, the detonation of an improvised nuclear device or a nuclear bomb could serve as sources of radioactive iodine

So-called “dirty bombs” – more formally referred to as radiation dispersal devices or RDDs – in which a conventional explosive is laced with radioactivity – represent an unlikely source of exposure to radioactive iodine

Therefore – victims of a “dirty bomb” attack – are unlikely to need treatment with KI

## PharmacotherapyPotassium Iodide

**Blockade of radioactive iodine uptake is time-dependent**
**KI is 80% effective at 2 hours post-exposure; 40% effective at 8 hours**

- Source: Health Physics [2000]. 78(6):660-7.

**Notes:**
As I said earlier, KI must be administered within hours following a radiological mass casualty event
As seen in the graph on this slide, the effectiveness of KI is highly time-dependent  
Taken as early as 24 hours in advance of an exposure to radioactive iodine, KI can provide near total blockade of radioactive iodine uptake

As soon as exposure has occurred, however, the effectiveness of this drug falls rapidly
At 2 hours post-exposure, KI is 80% effective in in blocking radioactive iodine uptake
At 8 hours, it is 40% effective
By 24 hours, KI provides little effective blockade and radioactive iodine has been incorporated into the thyroid gland

## PharmacotherapyPotassium Iodide

**Thyroid of fetus and young children more sensitive to carcinogenic effects of radioiodine**
**Radioiodine uptake inversely proportional to thyroid size**

**Notes:**
The populations most sensitive to the effects of radioactive iodine exposure – cancer of the thyroid – are among the youngest

During the years following the Chernobyl nuclear power plant disaster, it was discovered that children developed cancer of the thyroid at rates much greater than adults having similar levels of exposure

Thus, according to current treatment recommendations, the threshold for initiating treatment with KI in children and in pregnant mothers after a radiation mass casualty event is lower than it is for non-pregnant adults

## PharmacotherapyPotassium Iodide

**Administration guidance available from US Food and Drug Administration (FDA)**
**Guidance based on prevention of thyroid cancer **

- Source: Potassium Iodide as a Thyroid Blocking Agent in Radiation
- Emergencies [2001].  http://www.fda.gov/cder/guidance/4825fnl.pdf

**Notes:**
Additional guidance concerning the administration of KI – including dosages and dosing schedules – is available from the US Food and Drug Administration and may be found on their website listed at the bottom of this page

## PharmacotherapyPrussian Blue

**Ferric (III) hexacyanoferrate (II) (Radiogardase®)**
**Orally administered decorporation agent (capsules)**
**Promotes fecal excretion of radioactive cesium and thallium**

**Notes:**
The next drug I will discuss is Prussian Blue or Ferric hexacyanoferrate

In January, 2003, the Food and Drug Administration determined that Prussian blue had been shown to be safe and effective in treating people exposed to radioactive elements such as 137Cs

This orally administered decorporation agent acts by adsorbing radioactive cesium and thallium within the gastrointestinal tract and promoting the excretion of these isotopes in the stool

## PharmacotherapyPrussian Blue

**Binds isotopes in gastrointestinal tract via ion-exchange, adsorption, and mechanical trapping; limits entero-hepatic recirculation**
**Does not treat complications of radiation exposure**
**Need concomitant supportive care**

**Notes:**
Once absorbed into the body, cesium and thallium are removed by the liver, passed into the intestine and then re-absorbed into the bloodstream from the intestinal lumen – a process known as entero-hepatic recirculation.

Prussian blue traps thallium and cesium in the intestine, so that they can be passed out of the body in the stool rather than be re-absorbed

Prussian blue does not, however, treat the complications of radiation exposure – supportive care will undoubtedly be required

This means the use of antibiotics, antiemetics, nutritional support, intravenous fluids, and irradiated blood products/platelet transfusions as necessary

## PharmacotherapyPrussian Blue

**Initiate treatment as soon as possible**
**Treat for minimum of 30 days**
**Duration based on level of contamination**
**Additional guidance**
**http://www.fda.gov/cder/drug/infopage/prussian_blue/default.htm**
**http://www.bt.cdc.gov/radiation/prussianblue.asp**
**http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202737.html **
**http://www.orau.gov/reacts/prussian.htm**** **

**Notes:**
Although it is preferable that treatment with Prussian blue begin as soon as possible after exposure, treatment may be delayed until adequate supplies of this agent are obtained

Even when treatment cannot be started right away, treatment with Prussian Blue is effective and should not be withheld – it should be administered as soon as it becomes available

Additional sources of guidance for Prussian blue administration are listed at the bottom of this slide

## PharmacotherapyDTPA

**Diethylenetriaminepentaacetate**
**Calcium (Ca) and zinc (Zn) salts**
**Intravenous chelating agents for**
**Plutonium, Americium, Curium**
**DO NOT USE for**
**Uranium, Neptunium**

**Notes:**
Calcium and zinc DTPA – diethylenetriaminepentaacetate – are chelating agents that effectively bind the transuranic, radioactive elements plutonium, americium, and curium

DTPA acts by exchanging cations for these specific radioisotopes which in turn form stable complexes with the DTPA ligand
The radioisotope-DTPA complex is then excreted in the urine

Although DTPA is an effective chelator for some transuranic radioisotopes It is important to remember that internal contamination with uranium and neptunium should not be treated with DTPA
Current recommendations for treating uranium call for alkalinizing the urine with bicarbonate in order to promote renal excretion
In the case of neptunium, it is postulated that DTPA forms an unstable complex that may result in increased deposition into bones

## PharmacotherapyDTPA

**Ca-DTPA **
**Administration within 6 hours of exposure is most effective**
**Initially 10x more effective than Zn-DTPA**
**24 hours post-exposure Ca-DTPA and      Zn-DTPA have equivalent efficacy**
**Causes depletion of zinc and magnesium**

**Notes:**
As with the other agents we have been discussing, the effectiveness of DTPA administration – particularly calcium DTPA – is time-dependent
When administered within the first 6 hours of exposure, calcium DTPA is maximally effective as a chelating agent, even exceeding the binding of zinc DTPA by as much as 10x
By 24 hours post-exposure, however, calcium and zinc DTPA have approximately equal efficacy

In addition, over time, calcium DTPA is associated with more complications than is zinc DTPA

Because zinc DTPA doesn’t deplete zinc and magnesium from the body like calcium DTPA does, it has a better safety profile over the long term

Therefore, current guidance recommends initiating chelation with calcium DTPA in the first 24 hours and then suspending its use – to be followed by zinc DTPA

## PharmacotherapyDTPA

**Ca-DTPA contraindications**
**Minors, pregnant women, serious kidney disease, bone marrow suppression**
**Check renal function prior to each administration**

**Notes:**
The use of zinc DTPA is also preferable to calcium DTPA among children, pregnant women, in people with serious kidney disease, or who have underlying bone marrow suppression

Clinicians should remember to check a patient’s renal function prior to each administration of calcium DTPA since this drug is known itself to be nephrotoxic

The use of this drug should be discontinued if proteinuria, hematuria, or casts develop during its use

## Additional Guidance
http://www.fda.gov/cder/drug/infopage/dtpa/default.htm
http://www.orau.gov/reacts/calcium.htm
http://www.orau.gov/reacts/zinc.htm
http://www.bt.cdc.gov/radiation/dtpa.asp  

**http://www.fda.gov/cder/drug/infopage/dtpa/default.htm**
**http://www.orau.gov/reacts/calcium.htm**
**http://www.orau.gov/reacts/zinc.htm**
**http://www.bt.cdc.gov/radiation/dtpa.asp****  **

**Pharmacotherapy****DTPA**

**Notes:**
Further guidance concerning the use, containdications, and adverse side affects associated with the use of calcium and zinc DTPA may be found at these sites.

## PharmacotherapyFilgrastim (Neupogen®)

**Colony Stimulating Factors (CSF)**
**Endogenous glycoproteins**
**Induce hematopoietic progenitor cells of bone marrow to proliferate and differentiate into specific mature blood cell types**

**Notes:**
The last agent I would like to discuss differs somewhat from the previous three in that it is neither a blocking agent nor is it a drug that promotes decorporation after internal contamination.

Instead, this drug – and others like it – are used to treat one of the more serious adverse effects of acute radiation syndrome: bone marrow suppression.

The drugs of this class are known as colony stimulating factors.

In fact, colony stimulating factors occur naturally within the body where they act to induce hematopoietic progenitor cells of the bone marrow to proliferate and differentiate into specific mature blood cell types.

## PharmacotherapyFilgrastim (Neupogen®)

**Filgrastim [Granulocyte-CSF (G-CSF)]**
**Genetically engineered protein**
**Daily IV or IM administration**
**Minimal effect on hematopoietic cell types other than neutrophil progenitors**

**Notes:**
One drug of this class – filgrastim – was genetically engineered to stimulate the proliferation and maturation of granulocytes.

It has been shown that filgrastim specifically activates the neutrophil progenitor cells.

Its effect on stimulating the proliferation of other hematopoietic precursor cells – other than neutrophils – is miminal. 

## PharmacotherapyFilgrastim (Neupogen®)

**FDA-approved for treatment of neutropenia resulting from myelosuppressive cancer therapy**
**Not approved for treatment of ARS**
**Used as investigational drug for persons with unintentional radiological exposures**

**Notes:**
Filgrastim has been used now for several years – with FDA approval – and with good effect – in the treatment of cancer patients receiving myelosuppressive therapies

Filgrastim has not been approved by the FDA for the treatment of bone marrow suppression following acute radiation exposure

However, it has been used with some success as an investigational drug in people who have had unintentional radiological exposures

Following a radiation mass casualty event, it is anticipated that filgrastim would be administered to victims suffering from bone marrow suppression secondary to acute radiation syndrome

## PharmacotherapyFilgrastim (Neupogen®)

**Side effects**
**Allergic reactions (< 1 in 4000 patients)**
**Good response to antihistamines, steroids, bronchodilators and/or epinephrine**
**~50% have recurrence on re-exposure**
**Fatal and non-fatal splenic rupture**
**Severe sickle cell crises in patients with sickle cell disease**

**Notes:**
Overall the safety profile of the colony stimulating factors is largely good but use of this class of drugs is not without potential adverse side effects

Allergic reactions have been reported in fewer than 1 in 4000 patients and the reactions all respond well to conventional therapies such as antihistamines and steroids

Less commonly there have been reports of fatal and non-fatal splenic rupture in patients receiving colony stimulating factors – patients receiving these drugs must be cautioned about reporting immediately any abdominal pain, left upper quadrant pain, or any left shoulder pain

Finally, in patients with sickle cell disease, the colony stimulating factors have induced severe sickle cell crises requiring hospitalization, IV hydration and aggressive pain management

## PharmacotherapyFilgrastim (Neupogen®)

**Additional Guidance**
**http://www.bt.cdc.gov/radiation/neupogenfacts.asp **
**http://www.accessdata.fda.gov/scripts/cder/onctools/labels.cfm?GN=Filgrastim   **

**Notes:**
Additional guidance information concerning the appropriate use of colony stimulating factors and figrastrim may be found at the web sites listed on this slide.

Oncology specialists in your own institution may also be able to provide you with information and answers to questions concerning the use of these drugs.

## TreatmentWrap-Up

**Pharmacotherapy must be administered quickly after exposure**
**Match the treatment to the exposure**
**Guidance is available from the FDA and CDC concerning appropriate administration**

**Notes:**
in most cases – in order to maximize efficacy – available pharmacotherapy for the treatment of internal contamination and acute radiation exposure – should occur in a timely fashion

Some drugs may have limited or no efficacy when administered too  long after a radiation exposure – this means that clinicians may need to begin some treatments in the absence of a definitive diagnosis

Treatment should be appropriate to the exposure – for example, administering KI to a population exposed to a “dirty bomb” detonation may not be appropriate and use of DTPA to treat internal contamination with uranium is contraindicated

Guidance concerning the use of these agents – many of which may be novel to you – is available from the US Food and Drug Administration and from the Centers for Disease Control and Prevention.