📖 Pharmacology

FUNDAMENTALS OF INJECTION TECHNIQUE

There are 6 basic techniques for achieving local anesthesia of the structures of the oral cavity:

 1. Nerve block

 2. Field block

 3. Infiltration/Supraperiosteal

 4. Topical

 5. Periodontal ligament (PDL)

 6. Intraosseous

 Nerve block- Nerve block anesthesia requires local anesthetic to be deposited in close proximity to a nerve trunk. This results in the blockade of nerve impulses distal to this point. It is also important to note that arteries and veins accompany these nerves and can be damaged. To be effective, the local anesthetic needs to pass only through the nerve membrane to block nerve conduction Field block/Infiltration/Supraperiosteal - Field block, infiltration and supraperiosteal injection techniques, rely on the ability of local anesthetics to diffuse through numerous structures to reach the nerve or nerves to be anesthetized:

  - Periosteum

 - Cortical bone

 - Cancellous bone

 - Nerve membrane

Topical - Topical anesthetic to be effective requires diffusion through mucous membranes and nerve membrane of the nerve endings near the tissue surface

PDL/Intraosseous - The PDL and intraosseous injection techniques require diffusion of local anesthetic solution through the cancellous bone (spongy) to reach the dental plexus of nerves innervating the tooth or teeth in the immediate area of the injection. The local anesthetic then diffuses through the nerve membrane

Pharmacology is the study of drugs and the way they interact with living systems.  Clinical pharmacology is the study of drugs in humans.

A drug is any chemical that can effect living processes.

Therapeutics: the medical use of drugs.

An ideal drug has several important properties.  Three of these properties are of utmost importance: effectiveness, safety and selectivity. 

Effectiveness: This is the most important quality that a drug can have.  Effectiveness refers to the drug's ability to do what it is supposed to do.

Safety:  Although no drug can be totally safe, proper usage can lessen the risks of adverse effects.

Selectivity:  A truly selective drug would have no side effects, and would effect only the body process' for which it is designed and given.  Therefore, there is no such thing as a selective drug.

Pharmacokinetics: The way the body deals with a drug.  Pharmacokinetics is concerned with the processes of absorption, distribution, metabolism and excretion.

Pharmacodynamics:  What a drug does to the body.

Pharmacokinetics and pharmacodynamics are two of the processes that determine how a person will respond to a drug.  Other factors include how a drug is administered (dose, route, and timing of administration), interactions with other drugs, and individual physiological variables (weight, age, function of body systems).

Selective serotonin reuptake inhibitors (SSRIs)

e.g. fluoxetine, paroxetine, citalopram, and sertraline
- Most commonly used antidepressant category
- Less likely to cause anticholinergic side effects
- Relatively safest antidepressant group in overdose
- Selectively inhibits reuptake of serotonin(5-HT)

Mode of Action;
- Well absorbed when given orally
- Plasma half-lives of 18-24 h allowing once daily dosagedaily dosage
- Metabolised through CYP450 system and most SSRIs inhibit some CYP isoforms
- Therapeutic effect is delayed for 2-4 weeks

ADVERSE DRUG REACTIONS

- Insomnia, increased anxiety, irritability
- Decreased libido
- Erectile dysfunction, anorgasmia, and ejaculatory delay
- Bleeding disorders
- Withdrawal syndrome