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![DILUTIONSOFVASOCONSTRICTORS
■ The dilution of vasoconstrictors is commonly referred to as a ratio (e.g., 1 to 1000 [written 1 : 1000]).
■ A concentration of 1 : 1000 means that 1 g (1000 mg) of solute (drug) is contained in 1000 mL of solution.
■ 1 : 1000 dilution contains 1000 mg in 1000 mL or 1.0 mg/mL of solution (1000 µg/mL).
■ To produce a 1 : 10,000 concentration, 1 mL of a 1 : 1000 solution is added to 9 mL of solvent (e.g., sterile water);
therefore 1 : 10,000 = 0.1 mg/mL (100 µg/mL).
■ To produce a 1 : 100,000 concentration, 1 mL of a 1 : 10,000 concentration is added to 9 mL of solvent; therefore 1 :
100,000 = 0.01 mg/mL (10 µg/mL).
■ The genesis of vasoconstrictor dilutions in local anesthetics began with the discovery of adrenalin in 1897 by Abel.
■ In 1903, Braun suggested using adrenalin as a chemical tourniquet to prolong the duration of local anesthetics.](https://image.slidesharecdn.com/vasoconstrictors-151229113723/75/Vasoconstrictors-11-2048.jpg)
Uploaded byDr. Anindya Chakrabarty
Vasoconstrictors
This document discusses vasoconstrictors which are added to local anesthetic solutions to oppose the vasodilatory effects of local anesthetics and prolong the duration and effectiveness of anesthesia. It describes how vasoconstrictors work by constricting blood vessels to decrease blood flow and absorption of the local anesthetic from the injection site. Common vasoconstrictors used include epinephrine, norepinephrine, and felypressin. Epinephrine is the most widely used vasoconstrictor in dentistry and has effects such as increasing heart rate, blood pressure, and acting as a bronchodilator. Proper selection of a vasoconstrictor depends on factors like the length and type of
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Vasoconstrictors
- 1.
- 2. ■ All clinicallyeffective injectable local anesthetics are vasodilators, the degree of vasodilation varying from significant (procaine) to minimal (prilocaine, mepivacaine) and also possibly with both the injection site and individual patient response. ■ 1. An increased rate of absorption of the local anesthetic into the cardiovascular system, which in turn removes it from the injection site (redistribution) ■ 2. Higher plasma levels of the local anesthetic, with an attendant increase in the risk of local anesthetic toxicity (overdose) ■ 3. Decrease in both the depth and duration of anesthesia because the local anesthetic diffuses away from the injection site more rapidly ■ 4. Increased bleeding at the site of treatment as a result of increased perfusion
- 3. ■ Vasoconstrictors aredrugs that constrict blood vessels and thereby control tissue perfusion.They are added to local anesthetic solutions to oppose the inherent vasodilatory actions of the local anesthetics. ■ 1. By constricting blood vessels, vasoconstrictors decrease blood flow (perfusion) to the site of drug administration. ■ 2. Absorption of the local anesthetic into the cardiovascular system is slowed, resulting in lower anesthetic blood levels. ■ 3. Local anesthetic blood levels are lowered, thereby decreasing the risk of local anesthetic toxicity. ■ 4. More local anesthetic enters into the nerve, where it remains for longer periods, thereby increasing the duration of action of most local anesthetics. ■ 5. Vasoconstrictors decrease bleeding at the site of administration; therefore they are useful when increased bleeding is anticipated (e.g., during a surgical procedure).
- 4. ■ The vasoconstrictorscommonly used in conjunction with injected local anesthetics are chemically identical or similar to the sympathetic nervous system mediators epinephrine and norepinephrine.
- 5. Chemical structure ■ Classificationof sympathomimetic drugs by chemical structure is related to the presence or absence of a catechol nucleus. ■ Catechol : orthodihydroxybenzene. Sympathomimetic drugs that have hydroxyl (OH) substitutions in the third and fourth positions of the aromatic ring are termed catechols. ■ Catecholamine: If they also contain an amine group (NH 2 ) attached to the aliphatic side chain ■ Epinephrine : H CH3 ■ Levonordefrine : CH3 H ■ Norepinephrine : H H
- 6. ■ Felypressin, asynthetic analog of the polypeptide vasopressin (antidiuretic hormone), is available in many countries as a vasoconstrictor.
- 7. MODES OF ACTION ■Adrenergic Receptors ■ proposed by Ahlquist in 1948 ■ alpha (α) - contraction of smooth muscle in blood vessels (vasoconstriction) ■ beta (β) - smooth muscle relaxation (vasodilation and bronchodilation) and cardiac stimulation (increased heart rate and strength of contraction). ■ Release of Catecholamines ■ act indirectly by causing the release of the catecholamine norepinephrine from storage sites in adrenergic nerve terminals ■ may exert direct action on α and β receptors ■ TACHYPHYLAXIS : – Successively repeated doses of these drugs will prove to be less effective than those given previously because of depletion of norepinephrine from storage sites. – Such phenomenon is less common with adrenergic receptor drugs
- 11. DILUTIONSOFVASOCONSTRICTORS ■ The dilutionof vasoconstrictors is commonly referred to as a ratio (e.g., 1 to 1000 [written 1 : 1000]). ■ A concentration of 1 : 1000 means that 1 g (1000 mg) of solute (drug) is contained in 1000 mL of solution. ■ 1 : 1000 dilution contains 1000 mg in 1000 mL or 1.0 mg/mL of solution (1000 µg/mL). ■ To produce a 1 : 10,000 concentration, 1 mL of a 1 : 1000 solution is added to 9 mL of solvent (e.g., sterile water); therefore 1 : 10,000 = 0.1 mg/mL (100 µg/mL). ■ To produce a 1 : 100,000 concentration, 1 mL of a 1 : 10,000 concentration is added to 9 mL of solvent; therefore 1 : 100,000 = 0.01 mg/mL (10 µg/mL). ■ The genesis of vasoconstrictor dilutions in local anesthetics began with the discovery of adrenalin in 1897 by Abel. ■ In 1903, Braun suggested using adrenalin as a chemical tourniquet to prolong the duration of local anesthetics.
- 13. PHARMACOLOGY OF SPECIFIC AGENTS ■Epinephrine ■ Norepinephrine (Levarterenol) ■ Levonordefrin ■ Phenylephrine Hydrochloride ■ Felypressin
- 14. name Proprio tery name Source Mode of action Myocar dium Pacema kercell Coronar y arteries Blood pressur e Cardiov ascular dynami c Vascula ture Hemost asis Respira tory system CNS Elimina tion Side effect Availabl e in dentistr y Max. dosage EPINEP HRINE Adrenali ne Synthet ic Adrenal medulla Direct acting on alpha & beta Cardiac output & rate increase d Ventricu lar tachyca rdia Dilation of arteries – increase blood flow SBP – increase d with low dose DBP – increase with large dose Decreas e in cardiac efficien cy Low dose – B2 recepto r affinity – vasodila tion High dose – α recepto r – vasocon striction With high conc.- hemost asis, Low concent ration – vasodila tion – postop bleed Broncho dilator Therape utic dosage not potent for CNS effect Throug h liver In urine Cardiac dysrhyt hmia Ventricu lar fibrillati on Cerebra l haemor rhage 1:20000 0 0.2 mg per appoint ment NOREPI NEPHRI NE Levoph ed, noradre naline Synthet ic, adrenal medulla , Mainly alpha affinity Increase d cardiac output Cardiac dysrhyt hmia Increase blood flow Increase d SBP & DBP Decreas ed cardiac efficien cy Increase d total peripher al resistan ce - No clinical effect By reuptak e at nerve endings Less frequen t than epineph rine 1:30000 0.34 mg for normal 0.14 mg for card. FELYPR ESSIN Octapre ssin Synthet ic Direct stimulat ion of smooth muscle - Nondys rhythm ogenic Impair blood flow through coronar y artery - - Constric tion of vessles with high dose - - Nil - Wide range of safety 0.03IU/ ml with 3% prilocrai ne 0.27 IU – 9 ml
- 15. EPINEPHRINE ■ Source: 80%…. ■ MOA - ■ Systemic Effects of Epinephrine – Myocardium - ↑ heart rate & cardiac output – B P- ↑ systolic pressure – Vasculature - – Respiratory - Bronchodilator – CNS - Not a potent CNS stimulant – Metabolism ■ Increase oxygen consumption ■ Glycogenolysis - ↑ blood sugar
- 16. EPINEPHRINE ■ Clinical Manifestationsof Epinephrine Overdose – CNS stimulation - fear, anxiety, tremor, pallor, dizziness – CVS - ■ Maximum Dose for Dental Appointment – Normal healthy patient 0.2 mg. per appointment – Significant cardiovascular impairment 0.04 mg per appointment
- 17. SELECTION OF AVASOCONSTRICTOR ■Length of the Dental Procedure ■ Requirement for Hemostasis ■ Medical Status of the Patient
- 18. ■ Lidocaine HCLinfiltration block ■ 2% − no vasoconstrictor 5-10* ≈10-20* ■ 2% + epinephrine 1 : 50,000 ≈60 ≥60 ■ 2% + epinephrine 1 : 100,000 ≈60 ≥60 ■ 2% + epinephrine 1 : 200,000 ≈60 ≥60 ■ Mepivacaine HCL ■ 3% − no vasoconstrictor 5-10* 20-40* ■ 2% + levonordefrin 1 :20,000 ≤60 ≥60 ■ 2% + epinephrine 1 :100,000 ≤60 ≥60 ■ Prilocaine HCL ■ 4% − no vasoconstrictor 10-15* 40-60* ■ 4% + epinephrine 1 : 200,000 ≤60 60-90 ■ Articaine HCL ■ 4% + epinephrine 1 : 100,000 ≤60 ≥60