Common Adjunctive Medications in General Nuclear Medicine (57,10,11,1520,23)

DrugIndicationDosePharmacokineticsMechanism of actionContraindications/cautionsAdverse effects/interactions
Chloral hydrateSedation in children30–50 mg/kg to maximum of 1 gGood gut absorption, rapid metabolism, and onset of action in 30–60 min; elimination half-life of 7–11 h and significant effects for 4–8 hProdrug; is converted to trichloroethanol, which modulates GABA to cause CNS depressionContraindicated in significant liver, kidney, or cardiac dysfunction; caution in respiratory insufficiency and known hypersensitivityNausea, vomiting, diarrhea, dizziness, ataxia, drowsiness, headache, confusion, and paradoxic excitement; potential interactions with ethanol, warfarin, and CNS depressants
Diazepam (benzodiazepam)Anxiolytic (claustrophobia)1–10 mg orally individualized by age and liver/kidney functionOnset, 15–45 min; peak 30–90 min; half-life 46 h; duration can be prolonged; 100% bioavailability orally; 98%–99% PPB; biphasic elimination with rapid component followed by slower half-life of 1–2 dCauses inhibition through modulation of GABA and neuronal inhibitionContraindicated in chronic obstructive pulmonary disease, severe liver or lung disease, sleep apnea, and hypersensitivity; caution in depression, dependence, glaucoma, liver or kidney dysfunction, depression, pregnancy, and lactationDrowsiness, sedation, muscle weakness, ataxia, vertigo, headache, confusion, and paradoxic excitement, all with increased risk in the elderly; potential interactions with CNS depressants, including antihistamines and drugs metabolized by liver
BisacodylLaxative for differentiating stool from diseaseSingle oral dose, 5–15 mgMinimal absorption after oral administration; onset, 6–8 hStimulant laxative; increases stool water retention and peristalsisContraindicated in bowel obstruction; caution in liver impairmentGastric irritation, cramping and fluid or electrolyte imbalance; potential interactions with medications that change gastric acidity
HeparinBlood labeling to prevent clotting10–15 units/mL of blood being labeled in vitroHighly plasma protein–bound with variable elimination based on dose (slow for low doses); rapid onset with effects lasting 3–6 hCombines with antithrombin III to inactivate numerous clotting factorsContraindicated in known sensitivity, acute bacterial endocarditis, and high bleeding risk; caution in anticoagulant use, asthma, liver dysfunction, and animal protein allergyBleeding, hemorrhage, and hypersensitivity; potential interaction with anticoagulants (including NSAIDs and aspirin)
  • PPB = plasma protein bond; NSAIDs = nonsteroidal antiinflammatory drugs.

  • Duration is period of significant or measurable effect. Some adverse effects are more likely when used therapeutically than in single interventional doses.