Calculation of Doses: Patient Parameters

Usual dose

• The usual dose of a drug produces the desired therapeutic effect in the majority of patients within a population group.

• The drug's usual dosage range is the safe and effective range for that population.

• Usual doses are based on clinical studies during drug development and postmarketing surveillance.

Individualized dosing

• Some patients require individualized dosing based on specific parameters like age, weight, body surface area, and health status.

• Individualized dosing is important for neonates, elderly patients, those with compromised organ function, critically ill patients, and those on toxic chemotherapeutic agents.

• Age, weight, and body surface area are commonly used factors for dosing calculations, especially in pediatrics and the elderly.

• Chemotherapeutic agents also involve unique dosing regimens compared to other drugs.

pediatric drug dosing

• depends on factors like age, weight, health, biologic functions, and drug metabolism.

• Neonates have underdeveloped biologic functions, like renal function, which affects drug elimination.

• Pharmacokinetic data and individual patient characteristics guide pediatric drug dosage calculations.

• Pediatric drug doses can be found in drug product literature and medical references.

Geriatric Patients

•Aging leads to declining functional capacities of organs and changes in drug response.

•Pharmacotherapy is more common in the elderly due to age-related conditions.

•Elderly patients commonly have multiple coexisting pathologies requiring multiple drugs.

•Medications for the elderly aim to relieve symptoms, manage diseases, improve function, and enhance quality of life.

•Physiologic functions peak before 30 years, followed by gradual linear decline.

Solid dosage forms

Like tablets and capsules are convenient and cost-effective for most people.

-However, they can be challenging for certain groups like pediatric, geriatric, or infirm patients to swallow.

Liquid dosage forms

such as oral solutions, syrups, suspensions, and drops are preferred for those patients.

• Liquid doses can be adjusted easily by changing the volume administered.

• Liquid medications can also be administered via oral feeding tubes if needed.

• Pharmacists can compound oral liquids from solid dosage forms when no liquid option is available.

Chewable tablets

and solid gel forms are used for pediatric and geriatric patients, as well as gummies

Injection routes

may be used for pediatric and elderly patients when oral administration is not feasible

Drug Dosage Based on Body Surface Area

Body Surface Area (BSA) method used for drug dosage calculation in two main patient groups:

◦ cancer patients receiving chemotherapy

◦ most pediatric patients

BSA calculation commonly applied to pediatric patients except neonates, who are often dosed based on weight and other factors.

Nomograms

•Nomograms are commonly used for calculating Body Surface Area (BSA) and often include both weight and height measurements.

•To determine an individual's BSA using a nomogram, a straight line is drawn connecting their height and weight.

•The point where this line intersects the center column on the nomogram indicates the person's BSA in square meters.

Chemotherapy

• Chemotherapy involves treating diseases with chemical drugs or chemotherapeutic agents.

• Primarily used in cancer treatment

• Chemotherapeutic agents destroy cancer cells by affecting DNA synthesis or function.

• Chemotherapy is administered orally, intravenously, continuously via infusion, and through other routes.

• Combination chemotherapy, using drugs with different mechanisms, enhances effectiveness, reduces side effects, and often includes two-agent, three-agent, or four-agent regimens.