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G. Elimination kinetics: © SPMM Course fall in the plasma drug concentration, which is caused by redistribution of the drug from the blood circulation into other tissues. The time taken for this redistribution to halve the initial peak concentration is the dis...

2. Indices of safety and efficacy: © SPMM Course 2. Indices of safety and efficacy: Quantal or dose-response curves: Quantal curves plot the percentage of a population showing a specified, predefined categorical drug effect against the dose or log dose adminis...

3. Variables affecting pharmacokinetics:

A. Changes in the elderly © SPMM Course 3. Variables affecting pharmacokinetics: A. Changes in the elderly Domains Change Effect Body composition An increase in total body fat. A decrease in total muscle mass (lean body mass). A decrease in total body water. A...

B. Changes in neonates:

C. Changes in pregnancy:

D. Changes with renal impairment: © SPMM Course may be 600ml/min as compared to 1200ml/min in young adults. Creatinine measurements can yield spurious results; hence GFR formulas must be used to correct for age and other variables. Nearly 40% renal function is...

4. Clinically relevant kinetics and interactions:

A. Tricyclic antidepressants: © SPMM Course 4. Clinically relevant kinetics and interactions: A. Tricyclic antidepressants:  The tricyclics are orally well absorbed but have variable time to achieve peak plasma concentration (1 to 12 h).  Many of them have a...

B. SSRIs © SPMM Course B. SSRIs  The SSRIs are rapidly absorbed. Sertraline availability may be increased by the presence of food.  Most are highly protein bound except escitalopram which is 56% bound.  Fluoxetine is metabolized to norfluoxetine, which has ...

C. Other antidepressants © SPMM Course C. Other antidepressants The MAOIs are all rapidly absorbed. For the irreversible MAOIs the half-life does not correlate with duration of action as the effects on the MAO enzyme are irreversible and new enzyme needs to be...

Terms used to describe therapeutic effects of antidepressants © SPMM Course compared to buspirone but achieves higher brain concentration in the brain. Buspirone acts as a partial agonist on serotonin 5-HT1A receptors – presynaptic agonism leads to inhibition ...

D. Mood stabilisers © SPMM Course D. Mood stabilisers Lithium is orally well absorbed but not metabolized in the liver; it is renally excreted. Lithium carbonate and citrate are not bioequivalent preparations; hence the careful prescribing practice is required...

E. Typical antipsychotics: © SPMM Course to about 75mL/min. The active CBZ-10,11-epoxide (CBZ-E) metabolite has a half-life of about 6 hr. The conventional form needs to be given in multiple divided doses while extended release can be given twice a day. A stea...

Depot atypicals © SPMM Course  Lipid storage and brain retention are significant; depot forms of haloperidol or fluphenazine may persist for 1 to 3 months.  Thioridazine has an active metabolite mesoridazine, and loxapine produces 7hydroxyloxapine.  Typical...

F. Atypical antipsychotics: © SPMM Course F. Atypical antipsychotics: All atypicals are orally well absorbed. Drug Half life Chlorpromazine equivalents (100mg/day CPZ or 2mg Haloperidol) Risperidone 15hrs 2 mg/day Clozapine 16hrs 50 mg/day Quetiapine 6hrs 75 m...

G. Antidementia drugs:

H. Other drugs: © SPMM Course be supplemented with oral risperidone for 3 weeks. Requires refrigeration as it is granular, not ester-based. o Olanzapine depot is a crystalline salt composed of olanzapine and pamoic acid with a half-life of 30 days and steady s...