Camellia sinensis
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Related to Thea sinensis: Camellia sinensis, Camellia assamica
black tea
(blak tee) ,Camellia sinensis
(trade name),English tea
(trade name),Theaflavin
(trade name)Classification
Therapeutic: central nervous system stimulantsAction
Black tea contains caffeine (2–4%) a methylxanthine that stimulates the CNS through adenosine receptor blockade and phosphodiesterase inhibition, relaxes smooth muscle in the airways, stimulates the heart and has diuretic effects. Theaflavins and tannins present in black tea are responsible for antioxidant properties.
Therapeutic effects
CNS stimulation.
Diuresis.
Elevated heart rate and BP.
Pharmacokinetics
Absorption: Unknown.
Distribution: Unknown.
Metabolism and Excretion: Unknown.
Half-life: Unknown.
Time/action profile
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| PO | unknown | unknown | unknown |
Contraindications/Precautions
Contraindicated in: Allergy or hypersensitivity to caffeine or tannin; Obstetric: Pregnancy and lactation (in high doses due to caffeine content).
Use Cautiously in: Cardiac arrhythmias; Diabetes; Peptic ulcer disease; Osteoporosis (caffeine increases urinary calcium excretion); Iron deficiency anemia (may worsen); Pediatric: Safety and efficacy has not been established in children.
Adverse Reactions/Side Effects
Cardiovascular
- arrhythmia
- hypertension
- tachycardia
Central nervous system
- insomnia
- tremor
Dermatologic
- rash
- hives
Endocrinologic
- hyperglycemia
Fluid and Electrolyte
- hypokalemia
- hyponatremia
Gastrointestinal
- constipation
- increased stomach acid
Hematologic
- iron deficiency
- microcytic anemia
Genitourinary
- diuresis
- increased urine sodium, potassium, and calcium levels
Musculoskeletal
- rhabdomyolysis (high doses)
Interactions
Cimetidine, disulfiram, fluvoxamine, phenylpropanolamine, fluoroquinolones, and estrogens can ↓ caffeine clearance and ↑ adverse effects. Caffeine can inhibit dipyridamole -induced vasodilation.Abrupt withdrawal of caffeine can ↑ lithium levels.Additive stimulatory effects with CNS stimulants.Caffeine can ↑ theophylline levels.May ↑ heart rate and BP when used with bitter orange.May ↑ stimulatory effects when taken with ephedra and green tea.Oral (Adults) Heart disease prevention—1–4 cups daily; Headache/mental performance—1–5 cups daily. One cup of black tea contains approximately 50 mg caffeine. A maximum of 8 cups/day has been suggested.
Availability
Tea leaves: OTC
Nursing implications
Nursing assessment
- Assess BP and heart rate periodically in patients at risk for cardiovascular side effects.
- Lab Test Considerations: Monitor liver and kidney function tests and blood glucose, plasma homocysteine, and uric acid levels periodically in patients with who drink large amounts of black tea.
Potential Nursing Diagnoses
Acute pain (Indications)Implementation
- Drink tea as desired.
Patient/Family Teaching
- Advise patient that chronic use of black tea may be habit-forming. Abrupt discontinuation may lead to withdrawal symptoms; decrease gradually.
Evaluation/Desired Outcomes
- Increased mental alertness.
- Increased urine output.
- Decrease in headache pain.
green tea
(green tee) ,Camellia sinensis
(trade name)Classification
Therapeutic: central nervous system stimulantsAction
Caffeine in green tea stimulates the CNS and cardiovascular system through adenosine receptor blockade and phosphodiesterase inhibition.
Therapeutic effects
Improved cognitive performance and mental alertness.
Pharmacokinetics
Absorption: Unknown.
Distribution: Unknown.
Metabolism and Excretion: Unknown.
Half-life: Unknown.
Time/action profile
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| PO | Unknown | Unknown | Unknown |
Contraindications/Precautions
Contraindicated in: Allergy/hypersensitivity; Pregnancy and lactation (doses >200 mg/day due to caffeine content ).
Use Cautiously in: Patients with caffeine sensitivity. Long term use of doses >250 mg/day may produce tolerance, psychological dependence, tachyarrhythmias, and sleep disturbances; Iron deficiency anemia (may worsen); Diabetes (may impair glucose control); Cardiac conditions (may induce arrhythmias in sensitive individuals); Bleeding disorders.
Adverse Reactions/Side Effects
Cardiovascular
- arrhythmia
- tachycardia
Central nervous system
- agitation
- dizziness
- excitement
- insomnia
- tremors
Gastrointestinal
- nausea
- vomiting
- diarrhea
- hepatotoxicity
- abdominal pain
Fluid and Electrolyte
- hypokalemia
Endocrinologic
- hyperglycemia
Hematologic
- prolonged bleeding time
Interactions
Green tea may ↓ effects of adenosine.↑ risk of bleeding with anticoagulants or antiplatelet agents.↑ effects of CNS stimulants.May impair glucose control from antidiabetic agents.abrupt withdrawal can ↑ lithium levels.May ↓ dipyridamole —induced vasodilation.verapamil can ↑ caffeine concentrations by 25%.additive effects with methylxanthines.↑ risk of adverse cardiovascular effects with bitter orange.↑ risk of hepatotoxicity with hepatotoxic herbs or supplements.↑ risk of seizures, hypertension or stroke with ephedra and creatine.Oral (Adults) Range: 1–10 cups/day. One cup provides approximately 60 mg of caffeine.
Availability
Tea leaves:
Nursing implications
Nursing assessment
- Monitor BP and heart rate periodically during therapy.
- Lab Test Considerations: Monitor serum glucose, homocysteine and uric acid levels periodically during therapy.
- Monitor liver and kidney function periodically during therapy.
Potential Nursing Diagnoses
Impaired memory (Indications)Implementation
- May be taken as tea or as an extract in capsules.
Patient/Family Teaching
- Advise women who may be pregnant or who are breastfeeding to limit green tea due to the caffeine content.
Evaluation/Desired Outcomes
- Improvement in memory.
Camellia sinensis,
n See green tea.