Lect 3

• Animals are often weighed in pounds, requiring a conversion to kilograms.
• The conversion from pounds to kilograms is done by dividing the weight in pounds by 2.
• Therapeutic drug monitoring (TDM) is a process that involves monitoring the levels of drugs in the body to ensure that they remain within a therapeutic range.
• The amount of milliliters to be given to the patient can be determined by the Body Surface Area (BSA) of a 44 lb dog in m2 and the concentration of the drug (2 mg/mL).
• TDM is indicated when there is a need to adjust the dose of a medication based on the patient's response.
• The steps of the target concentration strategy in TDM include setting a target concentration, determining the initial dose, and monitoring the patient's response.
• Equations for dose adjustment calculation in TDM include the initial dose, the target concentration, and the measured drug concentration.
• Dosage form used for a drug can be a tablet, capsule, or transdermal patch.
• Patient factors that affect a dose include age, weight, body surface area, liver and kidney function.
• Physical and chemical properties of a drug include being hydrophilic and lipophilic.
• Route of administration for a drug can be oral or intravenous.
• Dose is based on patient factors such as age, weight, body surface area, liver and kidney function.
• Biochemical and pharmacologic activity is related to ADME.
• Daily dosage rate should be expressed in milligrams per kilograms or milligrams per pound.
• Total dose is the schedule of dosing, for example, three times daily for 7 days.
• In TDM, doses, dosage, and drug concentration are defined as different terms.
• Factors to consider in determining doses for patients in TDM include the patient's age, weight, and medical history.
• Tubes of 127 g of ponazuril paste contain 150 mg ponazuril per gram.
• The dose of vincristine sulfate for lymphosarcoma in dogs is 0.5 mg/m2.
• The dose of most drugs used to treat neoplasm is calculated according to the body surface area (BSA) of the patient.
• The dose of methotrexate sodium for neoplastic disease in cats is 2.5 mg/m2 twice weekly.
• The maximum dose of doxorubicin in canine chemotherapy is 200 mg/m2.
• The dose of ponazuril for lymphosarcoma in dogs is 20 mg/m2 daily for 28 days.
• BSA is correlated with the weight of the animal, as seen in the table below.
• The dose of digoxin for large-breed dogs is 0.22 mg/m2.
• The dose is divided by the amount (concentration) of the drug in the pharmaceutical form (e.g., tablet or solution) to determine the actual amount of the pharmaceutical form to be administered.
• In the first step of the calculation, kilograms cancel out and leave only milligrams in the numerator.
• If the order is to just give a dog 300 mg of amoxicillin, then the ordered amount is simply divided by the concentration of the to determine the amount to be administered.
• Dose Calculation = 200 mg 100 mg/mL = 2 mL.
• If 100-mg amoxicillin tablets are available, the formula becomes as follows:
• Dose Calculation = 200 mg 100 mg/mL = 2 tablets.
• In the second step of the calculation, milligrams cancel out and leave only milliliters.
• If a 20-kg dog is to be given amoxicillin at the rate of 10 mg/kg and injectable amoxicillin at a concentration of 100 mg/mL is available, the dosage calculation would be as follows:
• This way, if toxicity is experienced because of the dose increase, it may manifest itself at the lower, less toxic dose.
• A conservative approach to dosage adjustment is to increase the dose incrementally, starting with a dose of 400 mg/day and increasing the dose to 500 mg/day.
• If a patient has drug concentrations outside the therapeutic range, the dose should be modified to change the drug concentrations into the therapeutic range by a proportional adjustment.
• Dosage adjustment involves calculating the new dose based on the measured drug concentration and the target concentration.
• A dose of 300 mg/day should be adjusted to 525 µg/mL, the new target concentration, by increasing the dose to 525 µg/mL.
• The Target Concentration (TC) Strategy involves estimating the initial dose, target dose, loading dose, maintenance dose, and assessing therapy.
• Revise Vd and/or CL based on measured drug concentration.