Codeine

Codeine is methyl morphine, with a methyl substitution on the phenolic hydroxyl group of morphine. It is more lipophilic than morphine and thus crosses the blood–brain barrier faster.

• classified as a simple, or mild analgesic, codeine is often used in low doses as an oral analgesic has a much better oral/parenteral absorption ratio than morphine.
• Effective for mild to moderate pain.
• Constipation occurs
• Dizziness may occur in ambulatory patients.
• More potent histamine-releasing action than does morphine.
• Should not be administered by IV injection.
• Extremely effective antitussive agent and is used therapeutically for suppressing cough.
• In contrast to morphine, codeine overdose can occasionally lead to the production of seizures.
• Seizures can be treated with barbiturates.
• Respiratory depression can be counteracted with Naloxone.
• orally, 30 mg of codeine is equi-analgesic to 600 mg of aspirin, however, the effects of the two are additive, and occasionally synergistic

Gastric acid neutralizers (antacids)

Antacids act primarily in the stomach and are used to prevent and treat peptic ulcer. They are also used in the treatment of Reflux esophagitis and Gastritis.

Mechanism of action: 

Antacids are alkaline substances (weak bases) that neutralize gastric acid (hydrochloric acid) they react with hydrochloric acid in the stomach to produce neutral or less acidic or poorly absorbed products and raise the pH of stomach secretion.

Antacids are divided into systemic and non-systemic.

• Systemic antacids (e.g. sodium bicarbonate) are highly absorbed into systemic circulation and enter body fluids. Therefore, they may alter acid–base balance. They can be used in the treatment of metabolic acidosis. 

Non-systemic: they do not alter acid–base balance significantly, because they are not well-absorbed into the systemic circulation. They are used as gastric antacids; and include:

• Magnesium compounds such as magnesium hydroxide and magnesium sulphate MgS2O3. They have relatively high neutralizing capacity, rapid onset of action, however, they may cause diarrhoea and hypermagnesemia.

• Aluminium compounds such as aluminium hydroxide. Generally, these have low neutralizing capacity, slow onset of action but long duration of action. They may cause constipation.

• Calcium compounds such as. These are highly effective and have a rapid onset of action but may cause hypersecretion of acid (acid - rebound) and milk-alkali syndrome (hence rarely used in peptic ulcer disease). 

Therefore, the most commonly used antacids are mixtures of aluminium hydroxide and magnesium hydroxide . 

GLP-1 analogs

Exenatide

Mechanism

GLP-1 is an incretin released from the small intestine that aids glucose-dependent insulin secretion
basis for drug mechanism is the observation that more insulin secreted with oral glucose load compared to IV 

Exenatide is a GLP-1 agonist

↑ insulin
↓ glucagon release
the class of dipeptidyl peptidase inhibitors ↓ degradation of endogenous GLP-1
e.g.) sitagliptin, -gliptins 
 

Clinical use
type II DM
 

Toxicity
nausea, vomiting
pancreatitis
hypoglycemia
if given with sulfonylureas

Pharmacodynamics

Pharmacodynamics is the study of what drugs do to the body and how they do it.

Dose-Response Relationships

- Basic Features of the Dose-Response Relationship:  The dose-response relationship is graded instead of all-or-nothing (as dose increases, response becomes progressively larger).

- Maximal Efficacy and Relative Potency

- Maximal Efficacy: the largest effects that a drug can produce

- Relative Potency:  Potency refers to the amount of drug that must be given to elicit an effect.

- Potency is rarely an important characteristic of a drug.

- Potency of a drug implies nothing about its maximal efficacy.
 

Patient positioning

The most common medical emergency encountered in the dental office setting is syncope. So patients in the supine or semi-supine position to improve venous return and cerebral blood flow provided that the position is tolerated by the patient and is appropriate for their medical condition.

Celecoxib

is a highly selective COX-2 inhibitor and primarily inhibits this isoform of cyclooxygenase, whereas traditional NSAIDs inhibit both COX-1 and COX-2. Celecoxib is approximately 10-20 times more selective for COX-2 inhibition over COX-1.

Being a sulphonamide can cause skin rash &  hypersensitivity rxn., occasional oedema& HT.

Indication

Osteoarthritis ( 100‐200mg BID ) , rheumatoid  arthritis, dysmenorrhea, acute gouty attacks,  acute musculoskeletal pain.