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Pharmacology

Classification

1. Natural Alkaloids of Opium

Phenanthrenes -> morphine, codeine, thebaine

Benzylisoquinolines -> papaverine, noscapine

2. Semi-synthetic Derivatives

diacetylmorphine (heroin) hydromorphone, oxymorphone hydrocodone, oxycodone

3. Synthetic Derivatives

phenylpiperidines pethidine, fentanyl, alfentanyl, sufentnyl

benzmorphans pentazocine, phenazocine, cyclazocine

propionanilides methadone

morphinans levorphanol

Oxyphenbutazone: one of the metabolites of  phenylbutazone. Apazone.  Similar to  phenylbutazone, but less likely to cause  agranulocytosis

TRIMETHOPRIM

It is a diaminopyrimidine. It inhibits bacterial dihydrofolate reductase( DHFRase).

In combination with sulphamethoxzole it is called Co-trimoxazole.

Spectrum of action

 S. Typhi. Serratia. Klebsiela and many sulphonamide resistant strains of Staph.aureus. Strep pyogens

Adverse effects

Megaloblastic anemia. i.e.. due to folate defeciency.

Contraindicated in pregnancy.

Diuretics if given with co-trimoxazole cause thrombocytopenia.

Uses

I. UTI. 2. RTI. 3. Typhoid. 5. Septicemias. 5. Whooping cough

 

Isoflurane (Forane) MAC 1.3%, Blood/gas solubility ratio 1.4
- Better muscle relaxation than with the other halogenated anesthetic agents.
- Isoflurane markedly potentiates the action of the neuromuscular blocking agents.
- Produces rapid onset and recovery of anesthesia.
- Does not sensitize the heart to catecholamines.
- Produces respiratory depression, but produces less cardiovascular depression
- than does halothane.
- It has an extremely low degree of metabolism and is apparently relatively
- nontoxic.

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.

OXYMETAZOLINE
 

It is a directly acting sympathomimetic amine used in symptomatic relief in nasal congestion which increases mucosal secretion.

It is used:
- As a nasal decongestant in allergic rhinitis, with or without the addition of antazoline or sodium chromoglycate. 
- As an ocular decongestant in allergic conjunctivitis.

Compounds like naphazoline and xylometazoline are relatively selective α2 agonists, which on topical application produce local vasoconstriction.

Ofloxacin : It is a quinolone antibiotic and similar in structure to  levofloxacin. It is an alternative treatment to ciprofloxacin for anthrax.

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