Interacting drugs - summary

Dronabinol +

Amphetamine /  Cocaine/  Sympathomimetics} Anticholinergics/                           Antihistamines-                                                                                                            additive hypertension, tachycardia, possibly cardiotoxicity

 Anticholinergics/ Antihistamines-                                                                             additive or super-additive tachycardia, drowsiness 

Antidepresants- Tricyclic-                                                                                             additive tachycardia, hypertension, drowsiness

Alcohol/ Sedatives / Hypnotics/ Psychomimetics/-                                                         additive or synergistic CNS effects.Clearance of barbiturates decreased  

 Cannabinoids +

 Disulfiran-                                                                                                                           reversible hypomaniac reaction occured in a patient who smoked marijuana by rechallenge

Fluoxetine-                                                                                                                      patient with depression and bulimia became hypomaniac after smoking marijuana, symptoms resolved after 4 days

Theophylline-                                                                                                                     increased theophylline metabolism reported with marijuana smoking 

Antiemetic,appetite stimulation-treating anorexia associated with weight loss in AIDS patients 

Cardiovascular- Palpitations, tachycardia, vasodilation, conjuntivitis, hypotension.

GI- Nausea, vomiting, diarrhea, fecal incontinence, anorexia, hepatic enzyme elevation.

CNS- Euphoria, dizziness, paranoid reaction, somnolence, asthenia, amnesia, ataxia, confusion, depersonalization, hallucination, abnormal thinking

Special senses- Vision difficulties. tinnitus

Dermatologic- Flushing, sweating.

Respiratory- cough, rhinitis, sinusitis

Musculoskeletal- myalgias

Hypersensitivity to dronabinol

Special precautions:

Hypertension or heart disease- use with caution since dronabinol may cause a general increase in sympathomimetic activity.

Psychiatric patients- in maniac depressive or schizphrenic patients, symptoms of these disease state may be exacerbated by the use of canabinoids

Drug abuse and dependence- dronabinol is highly abusable. Limit prescriptions to the amount for a single cycle of chemotherapy

Hazardous tasks- because of its profound efects onmental status, warn patients not to drive, operate complex machinery or engage innany activity requiring sound judgement and unimpaired coordination while receiving treatment.

Warnings-

Patient supervision- because of individual variation, determine clinically the period of patient supervision required. Closely observe patients within an inpatient setting.

Elderly-use caution because elderly are generally more sensitive to the psychoactive effects. Pregnancy- use during pregnancy only if clearly needed.

Lactation- because the effects of infants of chronic exposure to the drug and its metabolite are unknown, nursing mothers should not use dronabiol.

Children- not recommended for AIDS- related anorexia in children because it has been studied in this population.

Dosage for chemotherapy-induced emesis is the same as in adults. Use caution in children because of psychoactive effects.

Indications:

Antiemetic,appetite stimulation-treating anorexia associated with weight loss in AIDS patients

Dosage:

Initially give 5mg/m2 1 to 3 hours prior to the administration of chemotherapy, then every 2 to 4 hours after chemotherapy is given, for a total of 4 to 6 doses a day.

Overdosage-

Symptoms-

Mild intoxification- drowsiness, euphoria, heightened sensory awareness,altered time perception, reddened conjunctiva,dry mouth, and tachycardia

Moderate intoxification- memoery impairment, depersonalization, mood alteration, urinary retention, and reduced bowel motility.

Severe intoxification- decreased motor coordination, lethargy, slurred speech and postural hypotension.

Apphrensive patients may experience panic reactions, seizures may occur in patients with existing seizure disorders The estimated lethal human dose of IV dronabinol is 30 mg.kg, Significant CNS symptoms in antiemetic studies followed oral doses of 4 mg/kg.

Treatment

1. Manage potentially serious oral ingestion, if recent gut decontamination.

2. In unconsious patients with a secure airway, instill activated charcoal via a nasogastric tube.

3. A saline cathartic or sorbitol may be added to the first dose of activated charcoal

4. Place patients experiencing depressive ,hallucinatory or phychotic reactionsin a quiet area and other reassurance.

5. Benzodiazepine ( 5 to 10mg oral diazepam ) may be used for treatment of extreme agitation.

6. Hypotension usually responds to Trendelburg position and IV fluids.

7. Pressors are rarely required.

 Missed dose-

1. If you miss a dose of this medicine, take it as soon as possible

. 2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule

. 3. Do not double doses.

1. Avoid alcohol and barbiturates.

2. May cause dizziness or drowsiness, do not drive or perform hazardous tasks requiring alertness, coordination or physical dexterity

. 3. Appraise patients of possible changes in mood and other adverse behavioural efects of the drug so they will not panic in the event of such manifestations.

4. Patients should remain under supervision of a responsible adult.

5. Allergies- Tell your doctor if you have ever had any unusual or allergic reactions to dronabinol, marijuana producs, or sesame oil. Also tell your doctor if your are allergic to any other substances such as foods, preservatives or dyes.

6. Pregnancy- studies in animals have shown that dronabinol given in doses many times the usual human dose increases the risk of death of the fetus and decreases the number of live babies born,

7. Breast feeding- there is a possibility that the baby may become dependent on this medicine

8. Children- no specific information comparing use of dronabinol in children with use in other age groups.Children should be watched closely while taking this medicine.

9. Elderly- Elderly people should be watched closely while they are taking this medicine

6. Other medicines- tell your doctor if you are taking any of the following- Central nervous system CNS- depresants medicines or Tricyclic antidepressants - takingthese medicines together with dronabinol may increase the CNS depressant effects.

7. Other medical problems- Alcohol abuse or Drug abuse or dependence - dependence may develop Heart disease or High blood pressure or Maniac depression or Schizophrenia - dronabinol may make the condition worse

15. Missed dose- If you miss a dose of this medicine take it as soon as possible. However if it is almost time for your next dose go back to your regular dosing schedule. Do not double doses.

Pharmacology:

Dronabiol is the principal psychoactive substance present in Cannabis sativa L(marijuana). Non therapeutic effects of dronabinol are identical to those of marijuna and other centrally active cannabinoids. The mechanism of action is not known.

Pharmacokinetics:

Following oral administration, dronabinol is almost completely absorbed (90 to 95%). It has a systemic bioavailability of 10 to 20% an onset of action of about 0.5 to 1hr and peak effect at 2 to 4 hours. Duration of psychoactive effects is 4 to 6 hours, but the appetite stimulant effect may continue for more than 24 hours after administration.

Pregnancy:

Use during pregnancy only if needed. Lactation: Nursing mothers should not use dronabinol.

Children-                                                                                                                                    Not recommended for AIDS- related anorexia in children because it has been studied in this population. 

Dosage for chemotherapy-induced emesis is the same as in adults. Use caution in children because of psychoactive effects.