Opiate Antagonists

Opiate antagonists have no agonist properties. They are utilized to reverse opiate induced respiratory depression and to prevent drug abuse.

A. Naloxone

 Pure opiate antagonist , Short duration of action,  Only 1/50th as potent orally as parenterally

B. Naltrexone

Pure opiate antagonist, Long duration of action, Better oral efficacy

Anticonvulsants: include carbamazepine (use when lithium not tolerated; may not be as effective) .

valproic acid (use when lithium not tolerated; rapid onset)

Antidepressant Drugs

Drug treatment of depression is based on increasing serotonin (5-HT) or NE (or both) at synapses in selective tracts in the brain. This can be accomplished by different mechanisms.

Treatment takes several weeks to reach full clinical efficacy.

1. Tricyclic antidepressants (TCAs)
a. Amitriptyline
b. Desipramine
c. Doxepin
d. Imipramine
e. Protriptyline

2. Selective serotonin reuptake inhibitors (SSRIs)
a. Fluoxetine
b. Paroxetine
c. Sertraline
d. Fluvoxamine
e. Citalopram

3. Monoamine oxidase inhibitors (MAOIs)
a. Tranylcypromine
b. Phenelzine

4. Miscellaneous antidepressants

a. Bupropion
b. Maprotiline
c. Mirtazapine
d. Trazodone
e. St. John’s Wort

Antimania Drugs

These drugs are used to treat manic-depressive illness.

1. Lithium
2. Carbamazepine
3. Valproic acid

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.

Tetracycline
Tetracycline is an antibiotic produced by the streptomyces bacterium

Mechanism and Resistance Tetracycline inhibits cell growth by inhibiting translation. It binds to the 30S  ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome. This prevents the addition of amino acids to the elongating peptide chain, preventing synthesis of proteins. The binding is reversible in nature.

Example: Chlortetracycline, oxytetracycline, demethylchlortetracycline, rolitetracycline, limecycline, clomocycline, methacycline, doxycycline, minocycline

Source: Streptomyces spp.; some are also semi-synthetic

Spectrum of activity: Broad-spectrum. Exhibits activity against a wide range of Gram-positive, Gram-negative bacteria, atypical organisms such as chlamydiae, mycoplasmas, rickettsiae and protozoan parasites.

Effect on bacteria: Bacteriostatic

Cells become resistant to tetracyline by at least two mechanisms: efflux and ribosomal protection.

Contraindications Tetracycline use should be avoided during pregnancy and in the very young (less than 6 years) because it will result in permanent staining of teeth causing an unsightly cosmetic result.

Tetracyclines also become dangerous past their expiration dates. While most prescription drugs lose potency after their expiration dates, tetracyclines are known to become toxic over time; expired tetracyclines can cause serious damage to the kidneys.

Miscellaneous: Tetracyclines have also been used for non-antibacterial purposes, having shown properties such as anti-inflammatory activity, immunosuppresion, inhibition of lipase and collagenase activity, and wound healing.

Monoamine oxidase inhibitors (MAOIs) 

e.g. phenelzine, tranylcypromine, moclobemide

- Belong to first generation antidepressants with TCAs
- Most MAOIs irreversibly inhibit the intraneuronal catabolism of norepinephrine and serotonin by MAO-A and MAO-B
- increase brain levels of noradrenaline and 5-HT
- Moclobemide causes selective, reversible inhibition of MAO-A

DRUG INTERACTIONS

Hypertensive crises similar to cheese reaction with OTC cough/cold preparations containing indirect-sympathomimetics
e.g. ephedrine

- Other antidepressants should not be started at least 2 weeks after stopping MAOIs and vice versa due to risk of serotonin syndrome
- Similar interaction with pethidine

ADVERSE DRUG REACTIONS

- Antimuscarinic side effects (e.g. dry mouth, blurred vision, urinary retention)vision, urinary retention)
- Excessive central stimulation causes tremors, excitement and insomnia
- Postural hypotension
- Increased appetite with weight gain