The radiopacity of ingested medications.

Area of Science:

• Radiology
• Pharmacology
• Forensic Science

Background:

• Radiopaque pills are crucial for identification in medical and forensic imaging.
• Existing methods for predicting pill radiopacity are often unreliable.

Purpose of the Study:

• To prospectively evaluate the radiopacity of common pharmaceutical pills.
• To identify reliable predictors of in vivo pill radiopacity.

Main Methods:

• 312 pills were initially radiographed through water (15-25 cm) to simulate human tissue density.
• Radiodense pills were further analyzed using computed tomography (CT) in a human cadaver model.
• Pill visibility on standard KUB radiographs was assessed.

Main Results:

• 35 of 312 pills were radiodense in water; 23 were radiopaque in the cadaver stomach.
• Common mnemonics for radiopaque pills were found to be inadequate.
• Consistent radiopacity was observed for chloral hydrate, iron, calcium carbonate, iodinated compounds, acetazolamide, busulfan, and potassium preparations.
• Variable radiopacity was noted for antihistamines, phenothiazines, tricyclic antidepressants, and pills from different manufacturers.
• Enteric coatings did not guarantee radiopacity.
• Radiographing pills outside the body can create false positives.
• Radiographing through 15 cm of water and CT radiodensity >1,300 Hounsfield units predicted cadaver radiopacity.

Conclusions:

• Pill radiopacity in vivo is complex and affected by numerous factors.
• Water-based and CT density assessments can predict radiopacity in a cadaver model.
• Standardized testing is needed to accurately identify radiopaque pills for clinical and forensic applications.