Chloramphenicol

derived from the bacterium Streptomyces venezuelae

Chloramphenicol is effective against a wide variety of microorganisms, but due to serious side-effects (e.g., damage to the bone marrow, including aplastic anemia) in humans, it is usually reserved for the treatment of serious and life-threatening infections (e.g., typhoid fever). It is used in treatment of cholera, as it destroys the

vibrios and decreases the diarrhoea. It is effective against tetracycline-resistant vibrios.It is also used in eye drops or ointment to treat bacterial conjunctivitis.

Mechanism and Resistance Chloramphenicol stops bacterial growth by binding to the bacterial ribosome (blocking peptidyl transferase) and inhibiting protein synthesis.

Chloramphenicol irreversibly binds to a receptor site on the 50S subunit of the bacterial ribosome, inhibiting peptidyl transferase. This inhibition consequently results in the prevention of amino acid transfer to growing peptide chains, ultimately leading to inhibition of protein formation.

Spectrum of activity: Broad-spectrum

Effect on bacteria: Bacteriostatic

Ciclopirox:Ciclopirox is a synthetic antifungal agent for topical dermatologic use.

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 

Propoxyphene

• A methadone analog.Used orally to relieve mild to moderate pain.
• A typical opiate, it does not possess anti-inflammatory or antipyretic actions, but has little or no antitussive activity.
• Cannot be used parenterally because of irritant properties.
• Has a low addiction potential primarily due to its lack of potency as an opiate.
• The most common adverse side effects are:• dizziness, drowsiness, and nausea and vomiting. • these effects are more prominent in ambulatory patients.
• Withdrawal symptoms have occurred in both adults and in neonates following use of the drug by the mother during pregnancy.
• CNS depression is additive with other CNS depressants.

Anticonvulsant Drugs

A.    Anticonvulsants: drugs to control seizures or convulsions in susceptible people

B.    Seizures: abnormal neuronal discharges in the nervous system produced by focal or generalized brain disturbances

Manifestations: depend on location of seizure activity (motor cortex → motor convulsions, sensory cortex → abnormal sensations, temporal cortex → emotional disturbances)

Causes: many brain disorders such as head injury (glial scars, pH changes), anoxia (changes in pH or CSF pressure), infections (tissue damage, high T), drug withdrawal (barbiturates, ethanol, etc.), epilepsy (chronic state with repeated seizures)

C.    Epilepsy: most common chronic seizure disorder, characterized by recurrent seizures of a particular pattern,  many types (depending on location of dysfunction)

Characteristics: chronic CNS disorders (years to decades), involve sudden and transitory seizures (abnormal motor, autonomic, sensory, emotional, or cognitive function and abnormal EEG activity)

Etiology: hyperexcitable neurons; often originate at a site of damage (epileptogenic focus), often found at scar tissue from tumors, strokes, or trauma; abnormal discharge spreads to normal brain regions = seizure

Idiopathic (70%; may have genetic abnormalities) and symptomatic epilepsy (30%; obvious CNS trauma, neoplasm, infection, developmental abnormalities or drugs)

Neuropathophysiology: anticonvulsants act at each stage but most drugs not effective for all types of epilepsy (need specific drugs for specific types)

Seizure mechanism: enhanced excitation (glutamate) or ↓ inhibition (GABA) of epileptic focus → fire more quickly → ↑ release of K and glutamate → ↑ depolarization of surrounding neurons (=neuronal synchronization) → propagation (normal neurons activated)

Treatment modifications to consider if there are concerns regarding vasoconstrictors

- Monitor blood pressure and heart rate preoperatively

- Minimize administration of epinephrine or levonordefrin

- Monitor blood pressure and heart rate 5 min after injection

- May re-administer epinephrine or levonordefrin if blood pressure and heart rate are stable

- Continue to monitor as required

- Consider limiting epinephrine to 0.04 mg, levonordefrin to 0.2 mg

- Avoid epinephrine 1:50,000

- Never use epinephrine-impregnated retraction cord