SSRIs are antidepressants that block the reuptake of serotonin.

SSRIs are not cholinergic antagonists or α-blockers.

Venlafaxine is an effective antidepressant that blocks reuptake of both serotonin and norepinephrine.

A related drug, atomoxetine, which is a selective norepinephrine reuptake inhibitor, is used to treat attention-deficit/hyperactivity disorder (ADHD).

The precise mechanism of action of the tricyclic drugs is unknown. These drugs block the reuptake of biogenic amines, including norepinephrine and serotonin.

MAO inhibitors increase levels of norepinephrine, serotonin, and dopamine by inhibiting their degradation.

MAO inhibitors can cause a fatal hypertensive crisis.

Bupropion is an effective antidepressant that is also approved for use (in combination with behavioral modification) in smoking-cessation programs.

Mirtazapine is an effective antidepressant that antagonizes central presynaptic α2 receptors.

Sibutramine is a norepinephrine, 5-HT and dopamine reuptake inhibitor that is used as a weight-loss agent.

LITHIUM, carbamazepine, and valproate are drugs used for the treatment of bipolar disorder.

LITHIUM has a low therapeutic index and the frequency and severity of adverse reactions is directly related to the serum levels.

Diuretics: Site of action & Mechanism

Osmotic Diuretics: =/=> water reabsorption throughout the tubules, but mostly in the proximal tubule (mannitol)

Carbonic Anhydrase Inhibitors: proximal tubule, =/=> C.A (acetazolamide, dorzolamide)

Loop Diuretics: thick ascending loop of Henle, =/=> Na+/K+/2Cl- transporter (furosemide, ethacrynic acid)

Thiazides: early distal tubule, =/=> Na+/Cl- symporter (hydrochlorothiazide, indapamide)

K+ sparing agents: distal nephron (late distal tubule + colecting ducts). Aldosterone receptor antagonist (spironolactone) or =/=> Na+/K+ exchange by =/=> of Na+ channels (amiloride, triamterene)

The penicillins, cephalosporins, vancomycin, imipenem, and aztreonam all work by inhibiting the synthesis of the bacterial cell wall.

Some bacteria inactivate the β-lactam antibiotics by an enzyme that opens the β-lactam ring.

CLAVULANIC ACID and SULBACTAM are β-lactamase inhibitors that are given together with the β-lactam drugs to increase their effectiveness.

Penicillins are excreted by tubular secretion that can be blocked by probenecid.

The most important adverse effect of penicillins as a group is the hypersensitivity reaction. It can be fatal.

All penicillins can give rise to allergic reactions. These reactions have been divided into three types: immediate, accelerated, and late. The immediate is the most severe.

The immediate reaction occurs within 20 minutes after parenteral administration and consists of apprehension, itching (pruritus), paresthesia (numbness and tingling), wheezing, choking, fever, edema, and generalized urticaria (hives). It can lead to hypotension, shock, loss of consciousness, and death. The immediate hypersensitivity reaction to penicillin appears to be mediated by IgE antibodies to the minor determinants.

The accelerated reaction appears 1-72 hours after drug administration and it consists mainly of urticaria (hives).

The late reaction is more common with the semisynthetics and appears 72 hours to several weeks after drug administration. It consists mainly of skin rashes.

CARBAPENEMS:
This class of β-lactam antibiotics contains imipenem, doripenem, ertapenem, and meropenem. All are administered intravenously.