Rx Note

Introduction During my time as a provisionally registered pharmacist rotating through Therapeutic Drug Monitoring (TDM), I realized that pharmacokinetic calculations were highly repetitive tasks. While pharmacokinetic modeling is useful, clinical decisions to withhold or adjust narrow therapeutic index drugs ultimately rely on the patient's clinical response. For instance, we monitor CRP, temperature, and white blood cell count for vancomycin and gentamicin, while actively tracking creatinine clearance changes for signs of toxicity. Mathematically, simply looking at a measured drug level often allows us to easily decide whether to withhold, adjust, or continue the current dose. This frequently renders subsequent pharmacokinetic calculations redundant. Consequently, I concluded that these calculations are primarily beneficial for dosage adjustments in toxicity cases. To streamline this process, I created an Excel-based TDM calculator in Excel sheet and OpenAsApp Link . The spreadsh...

Introduction Following reading of Before, With or After Food , let's now examine some drugs in particular. Gliclazide - Before or After Food All sulfonylureas are absorbed by the intestine, but each one with its specific absorption time and bioavailability. Hyperglycaemia can reduce the absorption of sulfonylureas as it impairs intestinal motility, thereby reducing the absorption of all orally administered drugs. For this reason, sulfonylureas should be taken 10-30 minutes before meals to optimize their absorption. However, sulfonylureas possess high risk of hypoglycaemia , hence many references recommend taking sulfonylureas with food, including Australian Medicines Handbook , British National Formulary , Lexicomp and MIMS Malaysia . Patients who take sulfonylureas with empty stomach should be aware of the symptoms of hypoglycaemia and how to manage it. The symptoms of hypoglycaemia include cold sweat, palpitations, hunger, fatigue and dizziness. Rivaroxaban - With Food A 2013 ...

Introduction Pharmacokinetics - The study of the time course of drug absorption, distribution, metabolism and excretion (ADME) . Pharmacodynamics - The relationship between drug concentration at the site of action and resulting effect, including the time course and intensity of therapeutic and adverse effects. Absorption With intravenous route, all of the administered drug is absorbed. However, if a drug is administered by any other route, it must be absorbed into the blood stream. This process may or may not be 100% efficient. Bioavailability (F) is the fraction of the administered dose which is absorbed into the bloodstream. It only estimates the extent of absorption, not take into consideration the rate of drug absorption. Factors that affect bioavailability include Inherent dissolution and absorption characteristics of the administered chemical form (e.g. salt, ester) The dosage form (e.g. tablet, capsule) The route of administration The stability of the active ingredient in the...

Introduction Tablets are widely used and generally preferred by patients for various reasons, including Ease of swallowing. Portability and compactness (in comparison to liquid formulations). Unlike injectable dosage forms , they are non-invasive and can be self-administered. The rate and extent of oral drug absorption are influenced by the Physiological factors associated with the structure and function of the gastrointestinal tract Physicochemical properties of the drug (e.g. solubility and dissolution rate) and dosage form factors In general, for oral absorption, a molecule should not violate more than one of the rules known as Lipinski's Rule of Five . The molecule should have No more than 5 hydrogen bond donors (-NH, -OH) No more than 10 hydrogen bond acceptors (-N, -O) A molecular mass less than 500 Da An octanol-water partition coefficient, log P, of not more than 5 Exceptions to the rule of 5 are those probably substrates for naturally occurring transporters, such as antib...