📖 Pharmacology
Needle selection
PharmacologyNeedle selection
Nerve blocks:
Inferior alveolar- 25 G short (LLU technique)
PSA- 25 G short
Mental/Incisive- 25 G short
Palatal- 27/30 G short/ultrashort
Gow-Gates/Akinosi- 25 G long
Infraorbital- 25 G long
Field Block:
ASA 25/27 short
Infiltration:
Infiltration/SP 25/27 short
PDL/Intraosseous
PDL 27/30 short
Intraosseous 30 short/ultrashort
Specific Agents
PharmacologySpecific Agents
Hydralazine [orally effective]
MOA: Not completely understood. Seems to be partially dependent on the release of EDRF and perhaps partially due to K+-channel activation
- in clinical doses action is manifest primarily on vascular smooth muscle (non-vascular muscle is not much affected).
- Re: Metabolism & Excretion. In cases of renal failure the plasma half life may be substantially increased (4-5 fold). One mode of metabolism is
via N-Acetylation (problem of slow acetylators)
Side Effects
- those typical of vasodilation = headache, nasal congestion, tachycardia etc.
- chronic treatment with high doses > 200 mg/day may induce a rheumatoid-like state which may resemble lupus erythematosus.
Minoxidil (Loniten) [orally effective]
MOA: K+-channel agonist
- very effective antihypertensive. Used primarily to treat life-threatening hypertension or hypertension resistant to other agents.
Side effects - growth of hair
Diazoxide (Hyperstat) [used only IV]
MOA: K+-channel agonist
- Administered by rapid IV injection; action appearing after 3-5 min; action may last from 4 to 12 hours.
Nitroprusside (Nipride) [used only IV]
MOA: increase in cGMP
- unlike the other vasodilators, venous tone is substantially reduced by nitroprusside.
- rapid onset of action (.30 sec); administered as an IV-infusion.
- particularly useful for hypertension associated with left ventricular failure.
Catecholamines Agonists
Pharmacology Catecholamines Agonists :
Epinephrine
A and B receptors - B1, A1, B2
- Good for emergency bronchospasm treatment (acute asthma or anaphylactic shock) and open-angle glaucoma
- Also gives longer duration of anesthetic action via vasocontriction and reducing systemic absorption
- Increases sBP lowers dBP
Norepinephrine
- A and B in therapeutic doses, most A receptor influence
- Good to increase peripheral resistance (A1)
- Good for shock treatment (increase TPR and BP); increases sBP and dBP
Isoproterenol
- Synthetic: B1 and B2, little A stimulation
- Strong cardiac stimulation (b1), dilation of skeletal vessels (b2), and bronchodilation (b2)
- Increases sBP lowers dBP
Dopamine
- Precursor to NE; A and B activity and dopamine receptors in renal and mesenteric vasculature causing vasodilation
- B1 stimulation of the heart
- Therapeutic: choice drug for shock as it increases BP via cardiac stimulation and also increases kidney blood flow (increased GFR and Na diuresis)
Dobutamine
- Synthetic B1 agonist
- To increase CO in CHF
- Watch out in Afib as it may increase AV conduction
Phenylephrine - Synthetic A1 agonist – for nasal decongestion
Methoxamine - Synthetic A1 agonist – for hTN in surgery
Clonidine - A2 agonist- - Used to lower pressure in essential HTN (via CNS effect, diminishing sympathetic outflow)
Dental implications of antiepileptic drugs:
PharmacologyDental implications of these drugs:
1. Adverse effects: gingival hyperplasia (phenytoin), osteomalacia (phenytoin, Phenobarbital), blood dyscrasias (all but rare)
2. Drug interactions: additive CNS depression (anesthetics, anxiolytics, opioid analgesics), induction of hepatic microsomal enzymes (phenytoin, Phenobarbital, carbamazepine), plasma protein binding (phenytoin and valproic acid)
3. Seizure susceptibility: stress can → seizures