ANTIDEPRESSANTS

Monoamine uptake inhibitors

1. Tricyclic antidepressants (TCAs)
2. Selective serotonin reuptake inhibitors (SSRIs)
3. Serotonin-norepinephrine reuptake inhibitors(SNRIs)
4. Norepinephrine reuptake inhibitor

Monoamine oxidase inhibitors (MAOIs) 

Monoamine receptor antagonists 

Nalidixic acid:

Nalidixic acid is the basis for quinolone antibiotics. It acts bacteriostatically (that is, it inhibits growth and reproduction) or bactericidally (it kills them) on both Gram positive and Gram negative bacteria, depending on the concentration. It is especially used in treating urinary tract infections, caused for example by Escherichia coli, Proteus, Enterobacter and Klebsiella.

Antimania Drugs

MANIC SYMPTOMSMANIC SYMPTOMS

Elevated  or irritable mood
Increased activity or psychomotor agitation
Reduced need for sleep
Inflated self esteem or grandiosity
Increased or pressure of speech
Flight of ideas

These drugs are used to treat manic-depressive illness.

1. Lithium
2. Carbamazepine
3. Valproic acid

Mechanisms of action

1. Lithium works inside the cell to block conversion of inositol phosphate to inositol.
2. Carbamazepine blocks sodium channels 
3. Valproic acid blocks sodium and calcium channels

PHARMACOKINETICS

Absorbed readily and almost completely from the GI tract; peak concentrations in 1-2 hrs

Lithium toxicity

1. Nausea, diarrhea, convulsions, coma, hyperreflexia, cardiac arrhythmias, hypotension.
2. Thyroid enlargement; increases thyroid stimulating hormone (TSH) secretion; may cause hypothyroidism.
3. Polydipsia, polyuria (lithium inhibits the effect of antidiuretic hormone on the kidney).

Clinical applications concerning lithium 

- Patients must be warned against sodium-restricted diets because sodium restriction leads to greater retention of lithium by the kidney.
- Patients must have regular (e.g., monthly) blood checks because the margin of safety is narrow.

Endocrine Effects – Goitre and hypothyroidism commonly

Cardiac Effects:– ECG changes(common) - T-wave flattening/inversion and appearance of U wavesflattening/inversion and appearance of U waves

Li and Pregnancy -1st Trimester:Cardiovascular anomalies of the newborn, especially Ebstein's malformation
- 3rd Trimester: Neonatal goiter, CNS depression, hypotonia ("floppy baby" syndrome)

Drug–drug interactions of lithium
Diuretics and newer nonsteroidal anti-inflammatory drugs (NSAIDs) reduce lithium excretion and may cause lithium toxicity.

Antifungal

There are several classes of antifungal drugs.

The polyenes bind with sterols in the fungal cell wall, principally ergosterol. This causes the cell's contents to leak out and the cell dies. Human (and other animal) cells contain cholesterol rather than ergosterol so are much less suceptible.

Nystatin

Amphotericin B

Natamycin

The imidazole and triazole groups of antifungal drugs inhibit the enzyme cytochrome P450 14α-demethylase. This enzyme converts lanosterol to ergosterol, and is required in fungal cell wall synthesis. These drugs also block steroid synthesis in humans.

Imidazoles:

Miconazole

Ketoconazole

Clotrimazole

The triazoles are newer, and are less toxic and more effective:

Fluconazole

Itraconazole

Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:

Terbinafine

Echinocandins inhibit the synthesis of glucan in the cell wall, probably via the enzyme 1,3-β glucan synthase:

Caspofungin

Micafungin

Others:

Flucytosine is an antimetabolite.

Griseofulvin binds to polymerized microtubules and inhibits fungal mitosis.

Erythromycin

used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including  mycoplasma. It is also used to treat outbreaks of chlamydia, syphilis, and gonorrhea.

Erythromycin is produced from a strain of the actinomyces Saccaropolyspora erythraea, formerly known as Streptomyces erythraeus.

Aquaretics
An aquaretic is a class of drug that is used to promote aquaresis, the excretion of water without electrolyte loss.

Lithium, demeclocycline

Mechanism of Action

1.    Block ADH action on distal tubule and collecting duct. Blocking ADH decreases H2O permeability. H2O is not recovered (distal tubule) using osmotic draw of counter-current multiplier so aquaretics reduce water reabsorption (tubule to blood stream). 
2.    Net effect is an increase in free water clearance