Local Anesthetic Agents in Clinical Use - PDF

Local Anaesthetic Agents In Clinical Use Dr. Omar Karadsheh Tala murad  Background Selection Of A Local Anaesthetic agent Outline Maximum doses of local anaesthetic agents Most common local anaesthetic agents used in...

Local Anaesthetic Agents In Clinical Use Dr. Omar Karadsheh Tala murad  Background Selection Of A Local Anaesthetic agent Outline Maximum doses of local anaesthetic agents Most common local anaesthetic agents used in dentistry Topical Anaesthetic agents  Selection of Local Anaesthetic agents The duration of pulpal (hard tissue) and soft tissue (total) anaesthesia needed. ( for example: lidocaine persists 1 hour in the pulp and 2 to 3 hours in soft tissues) Need for Postoperative pain management. Need for Haemostasis ( to stop bleeding - by vasoconstrictor ) Absolute and relative C/I ( contraindications )  Accuracy in deposition of the local anaesthetic. Anatomic variation. (Example: infiltration buccally for Very important slide lower 6 and 7 won’t be sufficient because of the thick buccal shelf ) Tissue status: 1) vascularity (high vascularity = wash out faster= shorter duration of anesthesia) 2) PH (anesthetic agent’s ph near to our soft tissue’s ph =7 , Duration and so in acidic environments ( inflammation )anesthesia won’t Depth of work sufficiently ) 3) buffered L.A ( to neutralize the acidic ph , by adding the Anaesthesia buffer to LA , but the problem here is that LA will become contaminated , so it’s better to be disposable ) + ( it improves the response of LA and it’s effectivity in infective area ) Type of injection administered ) ID block deeper than infiltration) Volume of L.A injected ( in ID block you give more anaesthesia than infiltration) Individual response to the drug (the “bell-shaped” curve) – next slide  Normal distribution curve (bell-shaped curve): Variation in individual response to a drug is common and expected and is depicted in the so-called bell or normal distribution. people are either hyper responders to the drug or hypo responders to it or normal responders.(in case you give them the same anesthetic volume)  Used mainly for children , ‫عشان ما يعضوا لسانهم‬ Short Duration (Pulpal Anesthesia Approximately 30 Minutes) Plain = without Mepivacaine HCl 3% vasoconstrictor Approximate Prilocaine HCl 4% (by infiltration) Intermediate Duration (Pulpal Anesthesia Approximately 60 Minutes) Duration of Articaine HCl 4% + epinephrine 1:100,000 Articaine HCl 4% + epinephrine 1:200,000 Action of Local Lidocaine HCl 2% + epinephrine 1:50,000 Lidocaine HCl 2% + epinephrine 1:100,000 Anaesthetics Mepivacaine HCl 2% + levonordefrin 1:20,000 Plain Prilocaine HCl 4% (via nerve block only) Used for cardiovascular patients + Prilocaine HCl 4% + epinephrine 1:200,000 patients with epinephrine sensitivity Long Duration (Pulpal Anesthesia Approximately 90+ Minutes) Bupivacaine HCl 0.5% + epinephrine 1:200,000 (by nerve block)  Maximum dose is Unlikely to be reached ( if you have a 70 kg patient, the maximum number of carpools to give are 10 carpools Maximum of lidocaine or articaine ) doses of L.A (mg/kg) or (mg/lb). Only estimated values (Bell-shaped curve): Normal responders Hypo-responders Hyper-responders Always minimize drug doses and use the smallest clinically effective dose Decreased in medically compromised, debilitated, or elderly persons Time of giving doses is also a factor ( giving 10 carpools in 10 min vs. giving 10 carpools in 1 hr ) , time must be sufficient , so the body can metabolize the excess of the dose.  ‫احفظوا بس ال‬ articaine and lidocaine 1 cartridge = 1.8 ml  Patient: 22 years old, Healthy, Female, 50 kg Calculation of L.A: Lidocaine HCL + Epinephrine 1:100,000 Maximum MRD Lidocaine: 7 mg/kg dosage and Lidocaine 2% → 2/100 x 1000 = 20 mg/ml Number of Cartridge contains 1.8 ml solution ,so → 20 x 1.8 = 36mg/cartridge Cartridges Maximum dose for this patient is: 7 mg/kg x 50 = 350 mg (single drug) Number of cartridges= 350/36 = ~10  Max. dose= Conc. X 10 x 1.8 Customized dose recommendation: for ‫لما يكون في‬ elderly patients for ‫نوعين تخدير‬ example, they have low ‫مناخد ال‬ metabolism, and they have maximum a lot of medications that ‫الوطى واحد فيهم‬ may have an effect in the ‫ بعدين منطرح‬، kidney , so it will affect the ‫ والباقي‬، ‫قديه اخد‬ wash out of the drug ( the ‫منقسمه على‬ drug will remain inside the ‫النوع الجديد‬ body for longer time , because the kidney is not functioning well ) so the probability of toxicity is higher in these patients , so you calculate a customized dose for them.  Local Anaesthetic Agents Used in Dental Injections Ester Type Amide Type ✓ Procaine ✓ Mepivacaine ✓ Propoxycaine HCl ✓ Prilocaine ✓ Mixture of Procaine + Propoxycaine ✓ Lidocaine ✓ Articaine Rare incident of allergy from ✓ Bupivacaine ester type , so they stop using it.  Procaine HCL Potency: 1 (Procaine=1) Toxicity: 1 (Procaine=1) Metabolism: Blood plasma (Pseudocholinesterase) Excretion:2% unchanged in urine: Onset of action: 6-8 min Effective concentration: 2%-4% Anaesthetic half-life: 6 min Topical anaesthetic action: N.A 2% procaine (plain) provides essentially no pulpal anaesthesia and from 15 to 30 minutes of soft tissue anaesthesia. the greatest vasodilation of all clinically used local anaesthetics.( = wash out faster = short duration of action) Immediate management of inadvertent intra-arterial (IA) injection of a drug  Propoxycaine Potency: 7-8 (Procaine=1) Toxicity: 7-8 (Procaine=1) Metabolism: Plasma & liver Excretion:Kidney Onset of action: Rapid (2-3 min) Effective concentration: 0.4% Anaesthetic half-life: N.A Topical anaesthetic action: N.A 0.4% propoxycaine/2% procaine with 1:20,000 levonordefrin (United States) or with 1:30,000 norepinephrine (Canada) provided approximately 40 minutes of pulpal anesthesia and 2 to 3 hours of soft tissue anaesthesia Amide-Type Local Anesthetics  Lidocaine ‫حكا الدكتور ال‬ onset of action ( safest) ‫مهمة‬ Potency: 2(Procaine=1) Toxicity: 2 (Procaine=1) Effective concentration: 2% Onset of action: Rapid (3-5 mins) Anaesthetic half-life: 90 min Topical anaesthesia: Yes (5%) Metabolism: Liver into two metabolites Excretion: Kidney Vasodilation properties: Procaine > Lidocaine > Prilocaine > Mepivacaine Lidocaine has a vasodilation property so we can’t use it as plain, we must use it with vasoconstrictor to elongate the duration of action. 60 minutes pulpal & 3 to 5 hours of soft tissue anaesthesia. (with vasoconstrictor) Pregnancy classification: B Safety during lactation: S  Lidocaine Lidocaine had replaced procaine (Novocaine) as the most widely used local anaesthetic in both medicine and dentistry. Compared with procaine, lidocaine possesses : ✓ a significantly more rapid onset of action (3 to 5 minutes vs. 6 to 10 minutes), ✓ produces more profound anaesthesia, ✓ has a longer duration of action, ✓ and has greater potency. Allergy to amide local anaesthetics is virtually non-existent; Excellent Hemostatic agent – high vasoconstrictor , good for stopping bleeding , but it may cause necrosis especially in the low blood supply areas like palate. “ used to stop intraoperative bleeding only , not post operative bleeding , because it will cause rebound vasodilation in case you use it post operatively , and the bleeding will occur again when the duration of action of the drug stops “. Lidocaine Preparations Preferred anesthesia Lidocaine preparations  Which Lidocaine preparation? For most procedures in a typical dental patient, 2% lidocaine with 1:100,000 epinephrine is preferred to 2% lidocaine with 1:50,000 epinephrine. The 1:50,000 solution provides excellent haemostatic action. The 1:100,000 dilution also may be used for hemostasis, but it is not as effective. Rebound vasodilation - epinephrine concentration decreases. The only recommended use of 2% lidocaine 1:50,000 epinephrine concentration is for haemostasis (small volumes into the surgical site). 2% lidocaine with 1:200,000 or 1:300,000 epinephrine provides the same duration of pulpal and soft tissue anaesthesia, although not the same level of haemostasis, their use is recommended in elderly patients or hyper-responders to epinephrine  Lidocaine Overdose Signs and symptoms of lidocaine toxicity (overdose) may be the same (central nervous system [CNS] stimulation followed by CNS depression) as other agents. However, the stimulatory phase may be brief or may not develop at all. Although muscle tremor and seizures commonly occur with overly high lidocaine blood levels, the first signs and symptoms of lidocaine overdose may include drowsiness, leading to loss of consciousness and respiratory arrest.  Mepivacaine HCl Potency: 2(Procaine=1) Toxicity: 1.5-2 (Procaine=1) Onset of action: Rapid (3-5 mins) Anaesthetic half-life: 1.9 hours Effective concentration: 3% plain, 2% with vasoconstrictor. Metabolism: Liver Excretion: Kidney Vasodilation properties: Slightly vasodilator Topical anaesthesia: N.A 20-40 minutes pulpal anaesthesia for plain (compared to 10-20min Lidocaine plain) Pregnancy classification: C ( not safe ) Safety during lactation: S ?  Three Percent Mepivacaine Without a Vasoconstrictor For patients in whom a vasoconstrictor is not indicated For dental procedures requiring neither lengthy nor profound pulpal anaesthesia. Mepivacaine plain is the most used local anaesthetic in paediatric patients when the treating doctor is not a paediatric dentist (e.g., is a general practitioner) and often is quite appropriate in the management of geriatric patients.  Two Percent Mepivacaine With a Vasoconstrictor, Levonordefrin 1:20,000 Depth and duration of anaesthesia is similar to Lidocaine combinations. Mepivacaine is available in combination with levonordefrin (1:20,000). (Where hemostasis is desired, epinephrine is preferred to levonordefrin) Signs and symptoms of mepivacaine overdose usually follow the more typical pattern of CNS stimulation followed by depression.  Prilocaine HCL Potency:2 (procaine = 1; lidocaine = 2). Toxicity: 1 (procaine = 1; lidocaine = 2); 40% less toxic than lidocaine ( safest ) Vasodilating Properties: Lidocaine > Prilocaine > Mepivacaine Onset of Action : Slightly slower than that of lidocaine (3 to 5 minutes). Effective Dental Concentration 4%. Anaesthetic Half-Life: 1.6 hours. Topical Anaesthetic Action: Not in clinically acceptable concentrations. Prilocaine, in its uncharged base form, is an integral part of EMLA cream  Prilocaine HCL Metabolism: Is significantly different from lidocaine and mepivacaine,it undergoes more rapid and complete biotransformation Orthotoluidine, a by-product, can induce methemoglobinemia →observable cyanosis. ( cannot be used with patients who have anemia ) Limiting the total prilocaine dose to 600 mg (FDA recommendation) avoids symptomatic cyanosis. Excretion: kidneys. Renal clearance of prilocaine is faster than for other amides, Pregnancy Classification B. Safety During Lactation : Unknown. Prilocaine Preparations  Infiltration with Prilocaine 4% plain provides short durations of pulpal (10 to 15 minutes) and soft tissue ( to 2 hours) anesthesia, whereas regional nerve block 40 to 60 minutes & soft tissue anesthesia for 2 to 4 hours. Thus prilocaine plain =lidocaine or mepivacaine with a vasoconstrictor. Prilocaine with epinephrine provides lengthy anaesthesia while offering a less concentrated epinephrine dilution: 1:200,000. In epinephrine-sensitive patients requiring prolonged pulpal anesthesia (≥60 minutes), prilocaine plain or with 1:200,000 epinephrine is strongly recommended. It is rapidly biotransformed and, for this reason, is considered to be a safe local anaesthetic (e.g., lower toxicity)  C/I of Prilocaine Prilocaine is relatively contraindicated in patients with idiopathic or congenital methemoglobinemia, hemoglobinopathies (sickle cell anemia), anemia, or cardiac or respiratory failure evidenced by hypoxia, because methemoglobin levels are increased, decreasing oxygen-carrying capacity. Prilocaine administration is also relatively contraindicated in patients receiving acetaminophen or phenacetin, both of which produce elevations in methemoglobin levels. Neurotoxicity and paresthesia ?  Articaine HCl Classification : Hybrid molecule. Classified as an amide; however, it possesses both amide and ester characteristics. Potency 1.5 times that of lidocaine; 1.9 times that of procaine. Toxicity Similar to lidocaine and procaine. Metabolism : both plasma and liver Excretion: Via kidneys Vasodilating Properties: Articaine = lidocaine.  Onset of Action: Articaine 1:200,000, infiltration 1 to 2 minutes, mandibular block 2 to 3 minutes; Articaine 1:100,000, infiltration 1 to 2 minutes, mandibular block 2 to 3 minutes. Effective Dental Concentration: 4% with 1:100,000 or 1:200,000 epinephrine. Anaesthetic Half-Life: 0.5 hours [27 minutes]. Topical Anaesthetic Action: N.A Pregnancy Classification: C. ( not safe ) Safety During Lactation: Unknown (use with caution in females who are breast-feeding because it is not known whether articaine is excreted in milk).  Articaine, as the newest local anaesthetic drug marketed It has been claimed that articaine is able to diffuse through soft and hard tissues more reliably than other local anesthetics Clinically, it is claimed that following maxillary buccal infiltration, articaine on occasion may provide palatal soft tissue anesthesia, obviating the need for palatal Articaine HCL injection The significant success of articaine administered by buccal infiltration in the mandible of adult patients. Reports of paraesthesia following local anaesthetic administration. An overwhelming majority of reported cases occurred following inferior alveolar nerve block and primarily involved the lingual nerve  Articaine HCL relative C/I Articaine HCl should be used with caution in persons with hepatic disease and significant impairment in cardiovascular function Class C drug during pregnancy. Use with caution in females who are breast-feeding Administration to children younger than 4 years is not recommended because insufficient data are available to support such usage. Bupivacaine HCl The longest acting drug Bupivacaine HCL  Bupivacaine HCL MRD bupivacaine is 90 mg. Bupivacaine is available as a 0.5% solution with 1:200,000 epinephrine Two primary indications for its utilization in dentistry: 1. Lengthy dental procedures for which pulpal (deep) anesthesia in excess of 90 minutes is necessary (e.g., full mouth reconstruction, implant surgery, extensive periodontal procedures) 2. Management of postoperative pain (e.g., endodontic, periodontal, postimplant, surgical) The patient's requirement for postoperative opioid analgesics is considerably lessened.  Relative C/I Bupivacaine is not recommended in younger patients or in those for whom the risk of postoperative soft tissue injury produced by self-mutilation is increased, such as physically and mentally disabled persons. Bupivacaine is rarely indicated in children because pediatric dental procedures are usually of short duration. Bupivacaine preparations Summary  Amides are preferred to esters whenever possible: A minimum of two drugs is recommended for most offices: 1 Short-duration pulpal anaesthetic (≈30 minutes) summary 2 Intermediate-duration pulpal anaesthetic (≈60 minutes) 3 Long-duration pulpal anaesthetic (90 or more minutes) 4 Topical anaesthetic for tissue preparation before injection of local anaesthetic  Anesthetics For Topical Application Conventional topical anesthetics are unable to penetrate intact skin but do diffuse through abraded skin and any mucous membranes. The concentration of a local anaesthetic applied topically is greater than that of the same local anaesthetic administered by injection. Higher concentration also increases the risk of toxicity (Do not contain vasoconstrictors) Many local anesthetics used effectively via injection prove ineffective when applied topically. As a general rule, topical anesthetics are effective only on surface tissues (2 to 3 mm).  The topical anesthetics benzocaine and lidocaine base (not the HCl form used by injection) are insoluble in water. However, they are soluble in alcohol, propylene glycol, polyethylene glycol, and other vehicles suitable for surface application. The base forms of benzocaine and lidocaine are slowly absorbed into the cardiovascular system and therefore are less likely to produce an overdose reaction following typical dental application. Topical L.A in Pressurized spray containers are difficult to control the amount of anaesthetic expelled and to confine it to the desired site of application. They are no more effective than other forms. Spray devices that do not deliver measured doses should not be used intraorally.  Topical Anaesthesia Topical anaesthesia need time to start working ( up to 45 min )  Benzocaine Benzocaine (ethyl p-aminobenzoate) is an ester Poor solubility in water Poor absorption into the cardiovascular system Systemic toxic (overdose) reactions virtually unknown Remains at the site of application longer, providing a prolonged duration of action Not suitable for injection Inhibits the antibacterial action of sulfonamides Availability (aerosol, gel, gel patch, ointment, and solution.)  Cocaine Ester that occurs naturally as a white crystalline solid that is highly soluble in water Used exclusively via topical application (injection is C/I) Onset of topical anaesthisa action is rapid (1 min). Duration up to 2 hours. It is absorbed rapidly but eliminated slowly, dosage is not carefully monitored. Cocaine is the only local anaesthetic consistently produce vasoconstriction Potentiate the actions of endogenous epinephrine and norepinephrine. psychological dependence and tolerance Clinical manifestations: CNS excitation, then depression ad death  It is recommended that the concentration of cocaine not exceed 4% for topical application to oral mucous membranes. Solutions of cocaine are unstable and deteriorate on standing. Because of the extreme abuse potential of cocaine, its use as a topical anesthetic in dentistry is not recommended. Topically applied cocaine is used occasionally before nasal-endotracheal intubation is performed in the operating theatre to minimize bleeding from this highly vascular region and pain as the endotracheal tube is passed.  EMLA (Eutectic Mixture of Local Anesthetics) EMLA cream (composed of lidocaine 2.5% and prilocaine 2.5%) provide surface anesthesia for intact skin Used primarily before painful procedures such as venepuncture EMLA must be applied 1 hour before the procedure., and lasts for 1 to 2 hours after removal. “EMLA is not recommended for use on mucous membranes,”???  Tetracaine Hydrochloride long-duration ester local anaesthetic that can be injected or applied topically, Highly soluble in water , Applied topically, five to eight times more potent than cocaine Onset of action after topical application is slow. Duration of action is approximately 45 minutes after topical application. Rapidly absorbed through mucous membranes. Use should be limited to small areas to avoid rapid absorption. Caution is urged because of great potential for systemic toxicity. Tetracaine in a 3% concentration, with the vasoconstrictor oxymetazocine, has been shown to provide pulpal anesthesia of maxillary teeth when administered by aerosol spray into a patient's nares  Lidocaine Lidocaine is available in two forms for topical application: ✓ lidocaine base, which is poorly soluble in water, used as a 5% concentration, indicated for use on ulcerated or abraded tissue; ✓ and lidocaine hydrochloride, its water-soluble preparation, used as a 2% concentration and penetrates tissue more efficiently than the base form. However, greater risk of toxicity than the base form. MRD following topical application is 200 mg. Availability: Lidocaine base is available as an aerosol spray, ointment, patch, and solution in various dosage forms Lidocaine HCl is available as an oral topical solution in 20 mg/mL (viscous) and 40 mg/mL (solution). Thank you