CNS Stimulants, Local Anesthetics & Fluid Therapy

Vocabulary flashcards covering CNS stimulants, local anesthetics, anesthesia routes, formulation components, and fluid therapy principles.

Respiratory Analeptic

Drug class that stimulates the CNS, respiratory, and cardiovascular systems to increase tidal volume.

Doxapram

Most-recommended CNS stimulant; activates carotid & aortic chemoreceptors—do NOT overdose (convulsions).

Halothane (as stimulant)

Volatile agent that stimulates the CNS and cardiovascular system when used as an analeptic.

Nikethamide

CNS stimulant with lethal action on the respiratory center—rarely used today.

Methylxanthines

Plant alkaloids (caffeine, theophylline, theobromine) that stimulate the cerebral cortex → ↑ motor & mental activity.

Caffeine

Coffee alkaloid; antioxidant; increases urinary & GI tract activity.

Theophylline

Tea alkaloid; lipolytic; bronchodilator—found in anti-asthmatic drug aminophylline.

Aminophylline

Ethylenediamine salt of theophylline; potent respiratory (anti-asthmatic) drug.

Theobromine

Chocolate alkaloid; antioxidant; stimulant of CNS.

4-Aminopyridine

Experimental CNS stimulant; antidote for curare overdosage.

Yohimbine

CNS stimulant & α2-adrenergic antagonist; reverses amitraz overdose and prevents sedation, arrhythmia, hypertension.

Tolazoline

α-adrenergic blocker with CNS stimulant & antihistamine actions; inhibits sympathetic nerves.

CO₂ as stimulant

Proper concentration increases respiratory drive by acting on the medullary center.

Strychnine

Alkaloid from Strychnos nux-vomica; powerful CNS, respiratory, CV stimulant—highly toxic.

Local Anesthetic

Drug applied to peripheral nerves to produce reversible loss of pain while consciousness is retained.

Topical Anesthesia

Application of anesthetic cream/ointment to skin or mucous membranes.

Infiltration Anesthesia

Subcutaneous injection of anesthetic that diffuses into surrounding tissues; most common route.

Conduction (Nerve Block)

Injection near a nerve trunk to block regional sensation.

Paravertebral Anesthesia

Injection around spinal nerves as they exit intervertebral foramina.

Epidural Anesthesia

Injection into epidural space between vertebrae and dura mater.

Intrathecal Anesthesia

Injection into cerebrospinal fluid in the subarachnoid space.

IV Regional (Bier) Block

Anesthetic injected into a limb isolated by tourniquet; surgeries <3 h.

Baricity

Specific gravity of spinal anesthetic; glucose added to create hyperbaric solution limiting ascent in CSF.

Vasoconstrictor (Epinephrine)

Added to LA to prolong action and localize drug by reducing blood flow.

Hyaluronidase

Dispersing enzyme that accelerates LA spread through tissues.

pH Alkalinizer

Onset promoter; alkalinizing LA speeds nerve penetration and action onset.

Preservatives in LA

Substances (EDTA, sodium metabisulfite, methylparaben, benzyl alcohol) that extend shelf life.

Procaine

Ester LA for infiltration, nerve block, paravertebral & epidural use.

Hexylcaine

LA usable topically and parenterally; same spectrum as procaine including epidural.

Lidocaine

Amide LA for infiltration, nerve block, epidural, topical; also class IB antiarrhythmic.

Tetracaine

Potent surface/conduction LA; lacks vasoconstriction—often combined with epinephrine; long-acting in ophthalmology.

Proparacaine

Surface ophthalmic LA preferred by many despite shorter duration than tetracaine.

Prilocaine

LA for epidural, intrathecal, infiltration & nerve block; longer duration than lidocaine.

Mepivacaine

Infiltration & nerve block LA; twice as potent as procaine with similar structure.

Bupivacaine

Long-acting LA for regional, spinal & epidural blocks; four times as potent as lidocaine.

Cetacaine

Topical mixture: 14 % benzocaine + 2 % tetracaine + 2 % butamben.

Benzocaine

Topical & infiltration LA widely used in dentistry.

Ropivacaine

Epidural & spinal LA almost as potent as bupivacaine; less cardiotoxic.

EMLA Cream

Eutectic mixture of 2.5 % lidocaine + 2.5 % prilocaine; synergy doubles potency & duration.

Fluid Therapy

Administration of fluids to correct dehydration, acid-base and electrolyte imbalances, or circulatory deficits.

Maintenance Dose (MD)

Normal water turnover (65 mL/kg adult; 130 mL/kg young/lactating) × body weight.

Replacement Dose (RD)

Degree of dehydration (%) × body weight (kg); 1 kg ≈ 1 L.

Continuing Dose (CD)

Ongoing fluid losses during treatment added to MD & RD.

Metabolic Acidosis (MAC)

Condition (e.g., diarrhea, renal disease) treated with sugar-containing fluids like LRS or D5W.

Metabolic Alkalosis (MAL)

Condition (e.g., emesis, diuretics) treated with salt-containing fluids like NSS or Ringer’s.

Respiratory Acidosis (RAC)

Hypoventilation disorders; manage with sugar-based solutions (LRS, D5W).

Respiratory Alkalosis (RAL)

Hyperventilation states; treat with salt-rich fluids (NSS, NH₄Cl).

Microdrip Set

Infusion set delivering 60 drops/mL; used for pediatric or small patients.

Macrodrip Set

Infusion set delivering 20 drops/mL; used for adult animals.

Total Fluid (TF) Formula

TF = Maintenance Dose + Replacement Dose + Continuing Dose.

Rate of Administration

(TF × drops/mL) ÷ 24 h → drops/hour → ÷60 for drops/minute.