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  5. Drug-Radiopharmaceutical Interactions

Drug-Radiopharmaceutical Interactions

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.


  • Drug-Radiopharmaceutical Interactions Handout
  • MIBG Interactions – European Journal of Nuclear Medicine and Molecular Imaging

Tc-99m Labeled Colloids

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Short-term chemotherapy e.g., carmustine, lomustineliver/spleen scintigraphya) irregular distribution of RP in liver b) hepatomegaly c) shift of RP from liver to spleen and/or bone marrow
Antacids; VirulizingAndrogen therapyliver/spleen scintigraphybone marrow scintigraphyDiffuse pulmonary accumulation
General anesthetic agentse.g., halothaneliver/spleen scintigraphyShift of RP from liver to spleen
Thorium Dioxideliver/spleen scintigraphyAbsence of spleen localization

Tc-99m Labeled Iminodiacetic Acid Derivatives

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Narcotic analgesics;PentobarbitalcholescintigraphyDelayed 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)cholescintigraphyPoor extraction and elimination of RP
Total parenteral nutritioncholescintigraphyAbsent or delayed visualization of gallbladder (in patients with no gallbladder disease)
Hepatic artery infusion of chemotherapyhepatobiliary scintigraphyno visualization of gallbladder

Tc-99m Labeled Phosphates & Phosphonates

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Iron containing compounds;Phospho-Sodaskeletal scintigraphyDecreased osseous uptake of bone imaging agents, and increased intravascular activity
Iron containing compounds;Amphotericin B; Gentamicin;   Cyclophosphamide; Vincristine; Doxorubicinskeletal scintigraphyIncreased renal retention of RP
Cytotoxic cancer chemotherapyskeletal scintigraphyDiffuse activity around the calvarium, termed “Sickle Sign”
Aluminum Containing Antacidsskeletal scintigraphyAppearance of liver
Sodium diatrazoleskeletal scintigraphyMarked renal and hepatic localization of RP
Regional chemoperfusion; Injection of Calcium Gluconate, Iron Dextran, Heparin Calcium, Mepiridineskeletal scintigraphyExtraosseous accumulation of RP
DES, Estrogensskeletal acintigraphyAccumulation of RP in breast tissue
Corticosteroidsskeletal acintigraphyDecreased or absent uptake of RP in bone, especially at major joints
E-Amino Caproic Acidskeletal scintigraphyIncreased RP uptake in muscle
Diphosphonateavid infarctscintigraphy (PPI)Decreased uptake in infarcted myocardium, and increased uptake in normal myocardium
Doxorubicinavid infarctscintigraphy (PPI)Diffuse uptake of RP in myocardium

Tc-99m Gluceptate

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Penicillin; Acetaminophen;Sulfamethoxazole/TrimetoprimRenal scintigraphyEnhanced excretion of RP through hepatobiliary system

Tc-99m Dimercaptosuccinic Acid (DMSA)

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON STUDY
Aluminum Chloriderenal scintigraphyDecreased renal distribution, and increased hepatic distribution
Sodium bicarbonate; Mannitolrenal scintigraphyIncreased RP in kidney
Captoprilrenal scintigraphyIn 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 DRUGSTUDY AFFECTEDEFFECT ON STUDY
HeparinPulmonary perfusion scintigraphyAppearance of perfusion image that is typically observed with pulmonary emboli

Tc-99m Pertechnetate

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Aluminum containing antacids;Sulfonamides; Stannous ion   containing drugs & RPsbrain scintigraphy;thyroid scintigraphy;   Meckel’s diverticulumFailure of RP to leave vascular space; Increased blood pool activity

Tc-99m Labeled Red Blood Cells

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
B-Adrenergic Blockers;Calcium Channel Blockers;   Nitratesradionuclide ventriculographynormal exercise radionuclide ventriculograms, evin in presence of signifigant coronary artery disease
Heparin; Methyldopa; Hydralazine;Quinine; Digoxin; Prazocin;   Propranolol; Doxorubicin; Iodinated Contrast Mediaradionuclide ventriculography;GI blood loss scintigraphyPoor 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
Doxorubicinradionuclide ventriculographyAbnormal ejection fraction; Decreased left ventricular function

In-111 Labelled DTPA & Yb-169 Labelled DTPA

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
AcetazolamidecisternographyDelayed parasagittal migration of RP with reflux of tracer into ventricles

In-111 Labeled White Blood Cells

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Antibiotics; Corticosteroids;Hyperalimentation; Lidocaine;   Procainamideinflammatory process scintigraphyDecreased or absent uptake of RP into abscess
Antibiotics, e.g., Penicillininflammatory process scintigraphyVisualization of colon

In-111 Labeled Platelets

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Heparinpulmonary embolus scintigraphyfailure of In-111 labeled platelets to identify sites of pulmonary emboli

I-131 & I-123

INTERFERING DRUGWITHOLDSTUDY AFFECTEDEFFECT ON IMAGE
Antithyroid Medications(PTU, tapazole)1 weekThyroid Uptake StudyDecreased Radioiodine Uptake
Thyroid Preparations(levothyroxine, Armour)2-3 weeks  
Expectorants,Vitamins2 weeks  
Phenylbutazone1-2 weeks  
Salicylates1 week  
Steroids1 week  
Sodium Nitroprusside1 week  
Miscellaneous:Anticoagulants   Antihistamines Antiparasitics Penicillins Sulfonamides Tolbutamide Thiopental1 week  
Benzodiazapines4 weeks  
Topical Iodides1-9 months  
IV contrast agents1-2 months  
Oral Cholecystographic Agents6-9 months  
Oil-Based IodinatedContrast Agents:   Bronchographic Myleographic6-12 months2-10 years  

I-131 Iodomethylnorcholesterol

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Spironolactone; OtherDiureticsAdrenal cortex scintigraphyBilateral uptake of RP in patients with unilateral disease
Oral ContraceptivesAdrenal cortex scintigraphyEarly bilateral visualization of the adrenals is observed in patients with no disease or unilateral disease only despite dexamethasone depression

I-131 Iodobenzylguanidine (mIBG)

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Tricyclic Antidepressants;Reserpine;   Sympathomimetic AminesAdrenal medullary scintigraphy 

Tl-201 Thallous Chloride

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Beta Blockers; NitratesMyocardial perfusion scintigraphyDecreases the number and size of exercise-induced Tl-201 perfusion defects
VasopressinMyocardial perfusion scintigraphyAppearance of myocardial defects in patients without coronary artery disease
Propranolol; Cardiac Glycosides;Procainamide; Lidocaine; Phenytoin;   DoxorubicinMyocardial perfusion scintigraphyDecreased myocardial localization and increased liver localization

Radiocyanocobalamin

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Parenteral Vitamin B12; Colchicine; Neomycin; p-Amino salicylic acid;Calcium chelators; Biguanides; Anticonvulsants; Potassium; Cholestyramine; Cyclohexamide; Dactinomycin; Oral contraceptivesSchilling TestDecreased absorption of RP

Radioxenon

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
Total parenteral nutritionPulmonary ventilation scintigraphyAppearance of radioactivity in liver during washout phase of ventilation study
Diazepam in sedative doses;General anesthetic agentsPulmonary ventilation scintigraphyNormal distribution shifted slightly (bottom to top), with more radioactivity in top and less in bottom

Ga-67 Citrate

INTERFERING DRUGSTUDY AFFECTEDEFFECT ON IMAGE
PhenytoinTumor & abscess localization scintigraphyLocalization 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 AbuseTumor & abscess localization scintigraphyDiffuse pulmonary localization (sometimes local pulmonary uptake)
Metocloperamide; Reserpine; Phenothiazines; Oral Contraceptives; DiethylstilbesterolTumor & abscess localization scintigraphyLocalization of RP in breast
Methotrexate; Cisplatin; Gallium Nitrate; Mechlorethenamine; Vincristine; Various Chemotherapeutic Agents; IronTumor & abscess localization scintigraphya) Increased skeletal uptakeb) Increased renal elimination   c) Decreased hepatic accumulation d) Decreased tumor or abscess uptake
Antibiotics (Clindamycin)Tumor & abscess localization scintigraphyLocalization of RP in bowel
Calcium Gluconate; IM injectionsTumor & abscess localization scintigraphySoft tissue accumulation of RP
Ampicillin; Sulfonamides; Sulfinpyrazone; Ibuprofen; Cephalosporins; Hydrochlorothiazide; Methicillin; Erythtomycin; Rifampin; Pentamidine; Phenylbutazone; Gold Salts; Allopurinol; Furosemide; Phenazone; Phenobarbital; Phenytoin; PhenindioneTumor & abscess localization scintigraphyIncreased accumulation of RP in the kidneys
Chemotherapeutic Agents; AntibioticsTumor & abscess localization scintigraphyLocalization of RP in the Thymus
High Dose Heparin TherapyRenal transplant rejectionFailure of RP to accumulate in transplanted kidney during acute rejection

Miscellaneous Radiopharmaceuticals Used to Evaluate Gastric Emptying

INTERFERING DRUGEFFECT ON IMAGE
Atropine; Propantheline; Levodopa; Albuterol; Isoproterenol; Narcotic Analgesics; Total Parenteral Nutrition; LibraxDelayed Gastric Emptying

Miscellaneous Brain Imaging Radiopharmaceuticals

INTERFERING DRUGEFFECT ON IMAGE
Cancer chemotherapeutic agentsPatchy increased uptake of RP as a result of chemo neurotoxicity
CorticosteroidsDecreased uptake into brain lesions
Psychotropic DrugsRapid accumulation of RP in nasopharyngeal area during arterial or capillary phase (cerebral radionuclide angiography)

Miscellaneous Renal Function Assessing Radiopharmaceuticals

INTERFERING DRUGEFFECT ON IMAGE
Iodinated Contrast Agents;AminoglycosidesDecrease in effective plasma flow values; Decreased glomerular filtration rate
Cyclosporine; CisplatinDecreased urinary excretion; Decreased tubular function
FurosemideMisleading renogram and flow curves resulting in false positive/negative studies
ProbenecidDecreased renal accumulation and accumulation
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