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.
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 |