Procaine penicillin Procaine penicillin is a combination of benzylpenicillin with the local anaesthetic agent procaine. This combination is aimed at reducing the pain and discomfort associated with a large intramuscular injection of penicillin.

Indications

respiratory tract infections where compliance with oral treatment is unlikely ,syphilis, cellulitis

Classification

I) Esters

 1. Formed from an aromatic acid and an amino alcohol.

 2. Examples of ester type local anesthetics:

 Procaine

Chloroprocaine

Tetracaine

Cocaine

Benzocaine- topical applications only

2) Amides

 1. Formed from an aromatic amine and an amino acid.

 2. Examples of amide type local anesthetics:

Articaine

Mepivacaine

Bupivacaine

Prilocaine

Etidocaine

Ropivacaine

Lidocaine

Pramlintide -Amylin mimetics

Mechanism
synthetic analogue of human amylin that acts in conjunction with insulin
↓ release of glucagon
delays gastric emptying

Clinical use

type I and II DM

Distribution

Three major controlling factors:  

Blood Flow to Tissues:  rarely a limiting factor, except in cases of abscesses and tumors.
Exiting the Vascular System:  Occurs at capillary beds.
- Typical Capillary Beds - drugs pass between cells 
- The Blood-Brain Barrier-  Tight junctions here, so drugs must pass through cells.  Must then be lipid soluble, or have transport system.
- Placenta - Does not constitute an absolute barrier to passage of drugs.  Lipid soluble, nonionized compounds readily pass.  
- Protein Binding:  Albumin is most important plasma protein in this respect.  It always remains in the blood stream, so drugs that are highly protein bound are not free to leave the bloodstream.  Restricts the distribution of drugs, and can be source of drug interactions.

Entering Cells:  some drugs must enter cells to reach sites of action.

Estimation of the risk of anesthesia (American Society of Anesthesiologists scale)

• ASA 1: healthy patient.

• ASA 2: patient with stable, treated illness like arterial hypertension, diabetes melitus, asthma bronchiale, obesity

• ASA 3: patient with systemic illness decreasing sufficiency like heart illness, late infarct

• ASA 4: patient with serious illness influencing his state like renal insuficiency, unstable hypertension, circulatory insuficiency

• ASA 5: patient in life treatening illness

• ASA 6: brain death- potential organ donor

PHARMACOLOGY OF VASOCONSTRICTORS

All local anesthetics currently used in dentistry today produce some degree of vasodilatation. This

characteristic results in the increased vascularity of the injected site and results in a shorter duration of local

anesthetic action due enhanced uptake of the local anesthetic into the bloodstream.

- Using a “chemical tourniquet” to prolong the effect of local anesthetics

- The vasoconstrictive action of epinephrine reduces uptake of local anesthetic resulting in a significant increase in the duration of local anesthetic action.

- the addition of vasoconstrictors in local anesthetic solutions will:

1. Prolong the effect of the local anesthetic

2. Increase the depth of anesthesia

3. Reduces the plasma concentration of the local anesthetic

4. Reduces the incidence of systemic toxicity

5. Reduces bleeding at surgical site

Local anesthetics containing epinephrine produce:

1. Localized

VASOCONSTRICTION MEDIATED BY ALPHA RECEPTOR ACTIVATION

 i. Hemostasis at surgical site

 ii. Ischemia of localized tissue

2. Systemic

HEART

 i. Increased heart rate (β1)

 ii. Increased force and rate of contraction (β 1)

 iii. Increased cardiac output

 iv. Increases oxygen demand

 v. Dilation of coronary arteries

 vi. Decreases threshold for arrhythmias 

LUNGS

 i. Bronchodilation (β2 )

SKELETAL MUSCLE
i. Predominately vasodilation (fight or flight response) (β 2 )

CNS

i. Minimal direct effect due to difficulty in crossing the blood-brain barrier. Most effects on the CNS are manifestations of the vasoconstrictor on other organs such as the heart.

Concentrations of vasoconstrictors

1. Epinephrine The most commonly used epinephrine dilution in dentistry today is 1:100000. However it appears that a 1:200000 concentration is comparable in effect to the 1:100000 concentration.

2. Levonordefrin Levonordefrin is a synthetic compound very similar in structure to epinephrine. It is the only alternate choice of vasoconstrictor to epinephrine. It is prepared as a 1:20000 (0.05mg/ml)(50 mcg/ml) concentration with 2 % mepivacaine.

Cardiovascular considerations

The plasma concentration of epinephrine in a patient at rest is 39 pg/ml.1 The injection of 1 cartridge of lidocaine 1:100000 epinephrine intraorally results in a doubling of the plasma concentration of epinephrine.

The administration of 15 mcg of epinephrine  increased heart rate an average of 25 beats/min with some individuals experiencing an increase of 70 beats/min.

Clinical considerations

It is well documented that reduced amounts of epinephrine should be administered to patients with:

HEART DISEASE (ANGINA HISTORYOF MI)

POORLY CONTROLLED HIGH BLOOD PRESSURE

It is generally accepted that the dose of epinephrine should be limited to 0.04 mg (40 mcg) for patients that have these medical diagnoses