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

Codeine

Codeine is methyl morphine, with a methyl substitution on the phenolic hydroxyl group of morphine. It is more lipophilic than morphine and thus crosses the blood–brain barrier faster.

• classified as a simple, or mild analgesic, codeine is often used in low doses as an oral analgesic has a much better oral/parenteral absorption ratio than morphine.
• Effective for mild to moderate pain.
• Constipation occurs
• Dizziness may occur in ambulatory patients.
• More potent histamine-releasing action than does morphine.
• Should not be administered by IV injection.
• Extremely effective antitussive agent and is used therapeutically for suppressing cough.
• In contrast to morphine, codeine overdose can occasionally lead to the production of seizures.
• Seizures can be treated with barbiturates.
• Respiratory depression can be counteracted with Naloxone.
• orally, 30 mg of codeine is equi-analgesic to 600 mg of aspirin, however, the effects of the two are additive, and occasionally synergistic

Azithromycin

Azithromycin is the first macrolide antibiotic belonging to the azalide group. Azithromycin is derived from erythromycin by adding a nitrogen atom into the lactone ring of erythromycin A, thus making lactone ring 15-membered.

Azithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Hemophilus influenzae.

azithromycin is acid-stable and can therefore be taken orally without being protected from gastric acids.

Main elimination route is through excretion in to the biliary fluid, and some can also be eliminated through urinary excretion

Buspirone

1. Short half-life (2–4 hours).
2. Relieves anxiety.
3. Does not act as an anticonvulsant.
4. Is not a good muscle relaxant.
5. Minimum abuse potential.

PHARMACOLOGY OF LOCAL ANESTHETICS

 Characteristics

1. Block axon conduction (nerve impulse) when applied locally in appropriate concentrations.

2. Local anesthetic action must be completely reversible; however, the duration of the anesthetic block should be of sufficient length to allow completion of the planned treatment.

3. Produce minimal local toxic effects such as nerve and muscle damage as well as minimal systemic toxic effects of organ systems such as the cardiovascular and central nervous system.

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

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