Pharmacology Essentials: Drug Interactions and Absorption

Hypotonic solutions contain fewer effective osmoles than what is found in the intracellular fluid space or interstitial space. Therefore, these types of fluids will quickly leave the intravascular space and redistribute to the interstitial space and intracellular fluid space. Think of hypotonic solutions as causing cell swelling because water is moving INTO the intracellular space.

Activated Charcoal does NOT absorb the toxin it coats the walls so toxin cannot get absorbed into the body. Activated charcoal does adsorb the toxin; that is it attracts and retains material so it can pass through the body and not be absorbed.

Opioids are classified by their action at the opioid receptor. There are three types of opioid receptors: mu kappa and delta. A pure mu agonist opioid will activate ALL of the opioid receptors. The commonly used opioid agonist drugs are: morphine oxymorphone hydromorphone meperidine methadone and fentanyl. Butorphanol is classified as an agonist/antagonist drug. They activate one type of opioid receptor and block another type. Butorphanol is a mu antagonist and a kappa agonist. Buprenorphine is considered a partial agonist at the mu receptor. It will stimulate the mu receptor producing some analgesia but is less effective than the pure mu agonist opioid drugs. Naloxone is an example of one reversal agent for the opioid drugs. It is considered an opioid antagonist.

The liver, kidney, intestines, lungs, milk, saliva, perspiration, urine, and feces are all routes of elimination for drugs.

Oral medications in tablet or pill form must first dissolve so that by the time it reaches the small intestine it can be absorbed. If gastric motility is too fast the drug misses the chance to be absorbed. If gastric motility it is too slow the amount of drug absorbed may be affected.

The use of Schedule Numbering (I, II, III, IV, etc.) indicates the level of potential abuse. The lower the number the higher the potential for abuse.

As part of the regulations to counteract drug diversion and because of the high potential for abuse the DEA requires Schedule II drugs to have a written prescription for each dispensing activity. Refills would require a new written prescription. Oral prescriptions for Schedule II can be given in an emergency with a written prescription completed as a follow-up.

Lethal dose divided by the effective dose equals the therapeutic index (LD50/ED50=TI). There is a greater margin of safety if there is a high therapeutic index; a LOT of difference between what is effective and what is lethal.

The LD50 represents the lethal dose in 50% of the test animals, meaning that half of the animals tested would die from the dosage of the substance given.

The Dose is a measure of an amount of substance (a drug) given at one time. If the patient weighed 10 kg using the dosage above the patient would be prescribed 100 mg would be a single dose. Concentration would be the amount of drug per unit of medication. Dosage regimen incorporates time as well such as 10 mg/kg every 8 hours.

Use the math conversion: 1% = 10mg/mL. Thus plugging in the numbers: 2.5 x 10 = 25mg/mL. Therefore 2.5% is equal to 25mg/mL.

Butorphanol and hycodan are antitussives. Diphenhydramine is an antihistamine.

The concentration of the medication is 12.5mg in 5mL of elixir. Divide 12.5mg by 5mL to get the concentration per mL (2.5mg/1 mL). Use cross multiplication of 2.5 mg/1 mL = 25mg/xmL > 2.5x = 25; solve for x; 25 divided by 2.5 = 10. Thus to administer 25mg of the medication you will need 10mL. The age and weight of the dog are irrelevant in this question.

Chloramphenicol is a known cause of aplastic anemia in humans.

First convert 42 pounds to kg: 42/2.2 = 19 kg; Next multiple the kg x dosage: 0.3mg/kg = 5.72 mg. The concentration of metoclopramide HCl is 5 mg/mL so divide 5.72 mg by 5. The answer is 1.14 or 1.1 matches that answer selection (C) for this case.

The liver metabolizes; the kidneys excrete; the stomach and intestine absorb.

The therapeutic dose produces a desired effect without toxicity. Maximum effect before toxicity has no specific term nor is there a specific term for minimum for sub-therapeutic dose. The LD50 dose is lethal in 50% of the cases.

Catecholamines mimic the effects of the hormones released by the core of the adrenal gland, which includes epinephrine and norepinephrine.

To administer 2mL draw up 2mL. 1.0 cc is the same measurement as 1.0 mL in fluid volumes.

The therapeutic index is the drug dosage or dose that produces the desired effect with minimal or no signs of toxicity. The maximum effect before toxicity has no specific term nor is there a specific term for the minimum for sub therapeutic dose. The LD50 dose is lethal in 50% of the cases.

The adrenal medulla releases epinephrine and norepinephrine when it is stimulated by the sympathetic nervous system.

When local or regional blocks are performed they will help decrease recovery time. The patient will recover more quickly from general anesthesia because local/regional blocks help decrease MAC which allows a lower inhalant concentration to be used during the procedure.