Visualize to Memorize

Excerpt from Cafer's Psychopharmacology , available soon from Amazon ENZYME IN D UCTION The opposite of in H ibition is in D uction . In D uction occurs when an in D ucer stimulates the liver to produce extra enzymes, leading to enhanced metabolism and quicker clearance of victim drugs. More often than not, an inducer is itself a substrate of the enzyme. The D is for D own, i.e., D ecreased serum concentrations of victim substrates. Unlike in H ibition ( H for H urried), in D uction is D elayed, not taking full effect for 2 to 4 weeks while we... wait for the liver to ramp up enzyme production. In D ucers will be depicted by:  THE SHREDDERS The “shredders” are four strong in D ucers of several CYPs, which cause countless chemicals to be quickly expelled from the body: carb amazepine (Tegretol) – antiepileptic pheno barb ital (Luminal) – barb iturat phenytoin (Dilantin) – antiepilepti rifampin (Rifadin) – antimicrobial Dr. Jonathan Heldt refers to the shredders as “Carb &...

Excerpt from Cafer's Psychopharmacology , available soon from Amazon ENZYME IN H IBITION In H ibition of an enzyme occurs when one drug (the in H ibitor) binds more tightly to the enzyme rather than a victim substrate. The in H ibitor itself may be metabolized by the enzyme, or act as a non-competitive inhibitor. When an inhibitor is bound to an enzyme, the victim substrate must find another enzyme to metabolize it, or hope that it can eventually be excreted unchanged. Strong inhibitors may cause the victim substrate to linger longer, prolonging the victim’s half-life and elevating its concentration in the blood. For victim substrates that cross the blood brain barrier (as is necessary to be psychoactive), inhibition leads to increased drug concentration in the central nervous system.   Why is H being emphasized? Well, when an in H ibitor is added to an individual’s medication regimen, levels of victim drugs can escalate ( H for H igh). In H ibition takes effect quickly, wi...

Excerpt from  Cafer's Psychopharmacology , available soon from Amazon SUBSTRATES A drug that is biotransformed by a particular enzyme is referred to as a substrate of that enzyme. When the substrate is biotransformed (metabolized) it is then referred to as a metabolite . Each CYP enzyme can metabolize several substrates and most substrates can be metabolized by several CYP enzymes. Substrates are the “victims” of the interactions described in this chapter. Throughout this book we use the following visuals for CYP substrates: “Aggressor” medications affect how long victim substrates linger in the blood, and the relative serum concentration of parent drug (substrate) to metabolite. For a given enzyme, interfering medications (aggressors) are either in D ucers or in H ibitors.  In D ucers stimulate (in D uce) production of metabolic enzymes.  In H ibitors interfere with an enzyme’s ability to metabolize other medications. PRODRUGS Phase I metabolism typically involves bio...

Excerpt from  Cafer's Mood Stabilizers and Antiepileptics PHARMACODYNAMICS VS PHARMACOKINETICS Drug-drug interactions fall into two main categories: pharmacokinetic and pharmacodynamic . Pharmacodynamics is what a drug does to the body. Pharmacodynamic interactions are based on the drugs’ mechanisms of action and do not involve alteration in blood levels of either interacting drug.  Pharmacokinetics is what the body does to a drug. Kin etic derives from the Greek verb kinein , "to move”. In this case we’re talking movement into and out of the body, for instance absorbing the chemical from the gut and processing it for excretion in urine or feces. Pharmacokinetic (PK) interactions are generally manifested by alteration of blood levels of one of the interacting drugs.  For simplicity’s sake, let’s drop the pharmaco- prefix and refer to these concepts as kinetic interactions and dynamic interactions. PHARMACODYNAMIC INTERACTIONS Dynamic interactions are intuitive if you und...

Excerpt from  Cafer's Mood Stabilizers and Antiepileptic Drugs ,  available on Amazon  ❖ Antiepileptic  ❖ Voltage-gated sodium  and calcium channel blocker  ❖ Glutamate ⇩  FDA approved for: ❖  Bipolar I maintenance ❖  Focal seizures ❖  Lennox-Gastaut syndrome  ❖  Bilateral tonic-clonic  seizures  Used off-label for: ❖  Bipolar II maintenance ❖  Major depressive  disorder ❖  Borderline personality  disorder ❖  Neuropathic pain ❖  Fibromyalgia ❖  PTSD ❖  Other seizure disorders  "Lamb ictal" - “Ictal” refers to a neurologic event such as a seizure.  Lamotrigine is the mood stabilizer of choice for maintenance of bipolar disorder . Lamotrigine has few health risks and few side effects . The most commonly reported side effects at high doses are dizziness and blurred vision . Lamotrigine does not cause weight gain and is generally non-sedating . No lab monitoring is...