Drug - Radiopharmaceutical Drug Interactions                                                       Return to Home

The following is a compilation of reported instances in which the biodistribution of a radiopharmaceutical (RP) has been (or could be ) modified by the administration of a therapeutic non-radioactive drug or contrast agent in such a way as to potentially interfere with the interpretation of the nuclear medicine study in question.  These lists are not meant to represent all possible interactions that exists.


Tc-99m Labelled Colloids | Tc-99m Labelled Iminodiacetic Acid Derivatives | Tc-99m Labelled Phosphates & Phosphonates Tc-99m Labelled Gluceptate | Tc-99m Labelled DMSA | Tc-99m Labelled MAA | Tc-99m Pertechnetate | Tc-99m Labelled Red Blood Cells | I-123 & I-131 | Tl-201| Radiocyanocobalamin | In-111 Labelled DTPA & Yb-169 Labelled DTPA | In-111 Labelled White Blood Cells | In-111 Labelled Platelets | Radioxenon| Gallium-67 Citrate | Miscellaneous Gastric Emptying Imaging Agents | Miscellaneous Brain Imaging Agents | Miscellaneous Renal Function Imaging Agents


Tc-99m Labeled Colloids

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Short-term chemotherapy
e.g., carmustine, lomustine
liver/spleen scintigraphy
a) irregular distribution of RP in liver
b) hepatomegaly
c) shift of RP from liver to spleen and/or bone marrow
Antacids; Virulizing

Androgen therapy

liver/spleen scintigraphy

bone marrow scintigraphy

Diffuse pulmonary accumulation
General anesthetic agents

e.g., halothane

liver/spleen scintigraphy Shift of RP from liver to spleen
Thorium Dioxide liver/spleen scintigraphy Absence of spleen localization

Tc-99m Labeled Iminodiacetic Acid Derivatives

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Narcotic analgesics;

Pentobarbital

cholescintigraphy Delayed biliary to bowel transit time with RP remaining in the gallbladder or in the common bile duct and not released into the duodenum
Nicotinic Acid (chronic,
high dose)
cholescintigraphy Poor extraction and elimination of RP
Total parenteral nutrition cholescintigraphy Absent or delayed visualization of gallbladder (in patients with no gallbladder disease)
Hepatic artery infusion of
chemotherapy
hepatobiliary scintigraphy no visualization of gallbladder

Tc-99m Labeled Phosphates & Phosphonates

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Iron containing compounds;

Phospho-Soda

skeletal scintigraphy Decreased osseous uptake of bone imaging agents, and increased intravascular activity
Iron containing compounds;

Amphotericin B; Gentamicin;

Cyclophosphamide; Vincristine;

Doxorubicin

skeletal scintigraphy Increased renal retention of RP
Cytotoxic cancer chemotherapy skeletal scintigraphy Diffuse activity around the calvarium, termed "Sickle Sign"
Aluminum Containing Antacids skeletal scintigraphy Appearance of liver
Sodium diatrazole skeletal scintigraphy Marked renal and hepatic localization of RP
Regional chemoperfusion;
Injection of Calcium Gluconate,
Iron Dextran, Heparin Calcium,
Mepiridine
skeletal scintigraphy Extraosseous accumulation of RP
DES, Estrogens skeletal acintigraphy Accumulation of RP in breast tissue
Corticosteroids skeletal acintigraphy Decreased or absent uptake of RP in bone, especially at major joints
E-Amino Caproic Acid skeletal scintigraphy Increased RP uptake in muscle
Diphosphonate avid infarct

scintigraphy (PPI)

Decreased uptake in infarcted myocardium, and increased uptake in normal myocardium
Doxorubicin avid infarct

scintigraphy (PPI)

Diffuse uptake of RP in myocardium

Tc-99m Gluceptate

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Penicillin; Acetaminophen;

Sulfamethoxazole/Trimetoprim

Renal scintigraphy Enhanced excretion of RP through hepatobiliary system

Tc-99m Dimercaptosuccinic Acid (DMSA)

INTERFERING DRUG STUDY AFFECTED EFFECT ON STUDY
Aluminum Chloride renal scintigraphy Decreased renal distribution, and increased hepatic distribution
Sodium bicarbonate; Mannitol renal scintigraphy Increased RP in kidney
Captopril renal scintigraphy In patients with hypertension and unilateral artery stenosis, there may be decreased renal uptake by the affected kidney

 


Tc-99m Labelled Macroaggregated Albumin & Albumin Microspheres

INTERFERING DRUG STUDY AFFECTED EFFECT ON STUDY
Heparin Pulmonary perfusion scintigraphy Appearance of perfusion image that is typically observed with pulmonary emboli

Tc-99m Pertechnetate

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Aluminum containing antacids;

Sulfonamides; Stannous ion

containing drugs & RPs

brain scintigraphy;

thyroid scintigraphy;

Meckel's diverticulum

Failure of RP to leave vascular space; Increased blood pool activity

Tc-99m Labeled Red Blood Cells

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
B-Adrenergic Blockers;

Calcium Channel Blockers;

Nitrates

radionuclide ventriculography normal exercise radionuclide ventriculograms, evin in presence of signifigant coronary artery disease
Heparin; Methyldopa; Hydralazine;

Quinine; Digoxin; Prazocin;

Propranolol; Doxorubicin;

Iodinated Contrast Media

radionuclide ventriculography;

GI blood loss scintigraphy

Poor labelling of RBC or post-labelling dissociation of Tc-99m; Deterioriation of distinctness of cardiac chamber border on ventriculograms; Free Tc-99m will appear as gastric or bowel activity on GI bleed studies
Doxorubicin radionuclide ventriculography Abnormal ejection fraction; Decreased left ventricular function

In-111 Labelled DTPA & Yb-169 Labelled DTPA

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Acetazolamide cisternography Delayed parasagittal migration of RP with reflux of tracer into ventricles

In-111 Labeled White Blood Cells

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Antibiotics; Corticosteroids;

Hyperalimentation; Lidocaine;

Procainamide

inflammatory process scintigraphy Decreased or absent uptake of RP into abscess
Antibiotics, e.g., Penicillin inflammatory process scintigraphy Visualization of colon

In-111 Labeled Platelets

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Heparin pulmonary embolus scintigraphy failure of In-111 labeled platelets to identify sites of pulmonary emboli

I-131 & I-123

INTERFERING DRUG WITHOLD STUDY AFFECTED EFFECT ON IMAGE
Antithyroid Medications

(PTU, tapazole)

1 week Thyroid Uptake Study Decreased Radioiodine Uptake
Thyroid Preparations

(levothyroxine, Armour)

2-3 weeks
Expectorants,

Vitamins

2 weeks
Phenylbutazone 1-2 weeks
Salicylates 1 week
Steroids 1 week
Sodium Nitroprusside 1 week
Miscellaneous:

Anticoagulants

  • Antihistamines
  • Antiparasitics
  • Penicillins
  • Sulfonamides
  • Tolbutamide
  • Thiopental
1 week
Benzodiazapines 4 weeks
Topical Iodides 1-9 months
IV contrast agents 1-2 months
Oral Cholecystographic Agents 6-9 months
Oil-Based Iodinated

Contrast Agents:

  • Bronchographic
  • Myleographic
6-12 months

2-10 years



I-131 Iodomethylnorcholesterol

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Spironolactone; Other

Diuretics

Adrenal cortex scintigraphy Bilateral uptake of RP in patients with unilateral disease
Oral Contraceptives Adrenal cortex scintigraphy Early bilateral visualization of the adrenals is observed in patients with no disease or unilateral disease only despite dexamethasone depression

I-131 Iodobenzylguanidine (mIBG)

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Tricyclic Antidepressants;

Reserpine;

Sympathomimetic Amines

Adrenal medullary scintigraphy

Tl-201 Thallous Chloride

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Beta Blockers; Nitrates Myocardial perfusion scintigraphy Decreases the number and size of exercise-induced Tl-201 perfusion defects
Vasopressin Myocardial perfusion scintigraphy Appearance of myocardial defects in patients without coronary artery disease
Propranolol; Cardiac Glycosides;

Procainamide; Lidocaine; Phenytoin;

Doxorubicin

Myocardial perfusion scintigraphy Decreased myocardial localization and increased liver localization

Radiocyanocobalamin

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Parenteral Vitamin B12; Colchicine; Neomycin; p-Amino salicylic acid;

Calcium chelators; Biguanides; Anticonvulsants; Potassium; Cholestyramine; Cyclohexamide; Dactinomycin; Oral contraceptives

Schilling Test Decreased absorption of RP








Radioxenon

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Total parenteral nutrition Pulmonary ventilation scintigraphy Appearance of radioactivity in liver during washout phase of ventilation study
Diazepam in sedative doses;

General anesthetic agents

Pulmonary ventilation scintigraphy Normal distribution shifted slightly (bottom to top), with more radioactivity in top and less in bottom

Ga-67 Citrate

INTERFERING DRUG STUDY AFFECTED EFFECT ON IMAGE
Phenytoin Tumor & abscess localization scintigraphy Localization of RP in the mediastinum & pulmonary hilar structures (in patients without clinical evidence of lymphadenopathy
Amiodarone; Bleomycin; Busulfan; Nitrofurantoin; Bacillus Calmette-Guerin; Chemotherapy; Lymphangiographic Contrast Media; Addictive Drugs of Abuse Tumor & abscess localization scintigraphy Diffuse pulmonary localization (sometimes local pulmonary uptake)
Metocloperamide; Reserpine; Phenothiazines; Oral Contraceptives; Diethylstilbesterol Tumor & abscess localization scintigraphy Localization of RP in breast
Methotrexate; Cisplatin; Gallium Nitrate; Mechlorethenamine; Vincristine; Various Chemotherapeutic Agents; Iron Tumor & abscess localization scintigraphy a) Increased skeletal uptake

b) Increased renal elimination

c) Decreased hepatic accumulation

d) Decreased tumor or abscess uptake

Antibiotics (Clindamycin) Tumor & abscess localization scintigraphy Localization of RP in bowel
Calcium Gluconate; IM injections Tumor & abscess localization scintigraphy Soft tissue accumulation of RP
Ampicillin; Sulfonamides; Sulfinpyrazone; Ibuprofen; Cephalosporins; Hydrochlorothiazide; Methicillin; Erythtomycin; Rifampin; Pentamidine; Phenylbutazone; Gold Salts; Allopurinol; Furosemide; Phenazone; Phenobarbital; Phenytoin; Phenindione Tumor & abscess localization scintigraphy Increased accumulation of RP in the kidneys
Chemotherapeutic Agents; Antibiotics Tumor & abscess localization scintigraphy Localization of RP in the Thymus
High Dose Heparin Therapy Renal transplant rejection Failure of RP to accumulate in transplanted kidney during acute rejection

Miscellaneous Radiopharmaceuticals Used to Evaluate Gastric Emptying

INTERFERING DRUG EFFECT ON IMAGE
Atropine; Propantheline; Levodopa; Albuterol; Isoproterenol; Narcotic Analgesics; Total Parenteral Nutrition; Librax Delayed Gastric Emptying




Miscellaneous Brain Imaging Radiopharmaceuticals

INTERFERING DRUG EFFECT ON IMAGE
Cancer chemotherapeutic agents Patchy increased uptake of RP as a result of chemo neurotoxicity
Corticosteroids Decreased uptake into brain lesions
Psychotropic Drugs Rapid accumulation of RP in nasopharyngeal area during arterial or capillary phase (cerebral radionuclide angiography)




Miscellaneous Renal Function Assessing Radiopharmaceuticals

INTERFERING DRUG EFFECT ON IMAGE
Iodinated Contrast Agents;

Aminoglycosides

Decrease in effective plasma flow values; Decreased glomerular filtration rate
Cyclosporine; Cisplatin Decreased urinary excretion; Decreased tubular function
Furosemide Misleading renogram and flow curves resulting in false positive/negative studies
Probenecid Decreased renal accumulation and accumulation

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