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 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; VirulizingAndrogen therapy | liver/spleen scintigraphybone marrow scintigraphy | Diffuse pulmonary accumulation |
| General anesthetic agentse.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 infarctscintigraphy (PPI) | Decreased uptake in infarcted myocardium, and increased uptake in normal myocardium |
| Doxorubicin | avid infarctscintigraphy (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 IodinatedContrast Agents: Bronchographic Myleographic | 6-12 months2-10 years |
I-131 Iodomethylnorcholesterol
| INTERFERING DRUG | STUDY AFFECTED | EFFECT ON IMAGE |
| Spironolactone; OtherDiuretics | 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 uptakeb) 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 |