What is the proper dosage and usage of Cialis (tadalafil) 10 mg for erectile dysfunction?

Cialis (Tadalafil) 10 mg: Dosage and Usage for Erectile Dysfunction

For most men with erectile dysfunction, start with tadalafil 10 mg taken as needed prior to anticipated sexual activity, with the option to increase to 20 mg or decrease to 5 mg based on response and tolerability. 1

Dosing Strategies

As-Needed (PRN) Dosing

• Initial dose: 10 mg taken prior to anticipated sexual activity 1
• Dose adjustment: May increase to 20 mg or decrease to 5 mg based on individual efficacy and tolerability 1
• Maximum frequency: Once per day in most patients 1
• Duration of effect: Tadalafil improves erectile function for up to 36 hours following dosing, allowing for greater spontaneity compared to shorter-acting PDE5 inhibitors 1
• Food considerations: May be taken without regard to food 1

Once-Daily Dosing Alternative

• Starting dose: 2.5 mg taken at approximately the same time every day, without regard to timing of sexual activity 1
• Dose adjustment: May increase to 5 mg based on individual efficacy and tolerability 1
• Advantage: Eliminates the need to time medication with sexual activity, providing an option for couples who prefer spontaneous rather than scheduled sexual activity 2

Efficacy Evidence

High-quality evidence demonstrates that tadalafil significantly improves erectile function, with 69% of men reporting successful sexual intercourse attempts compared to 33% with placebo. 3, 2

• Tadalafil improves erections in 73-88% of men compared to 26-32% with placebo 3
• Unlike sildenafil and vardenafil, tadalafil does not show dose-dependent improvement in erectile function between 5-20 mg doses 3, 2
• Efficacy is maintained across various etiologies of ED including diabetes, cardiovascular disease, depression, and post-prostatectomy 3

Critical Patient Instructions

Requirements for Effectiveness

• Sexual stimulation is necessary for tadalafil to work; the medication does not cause automatic erections 4, 2
• Multiple trials may be required: An adequate trial consists of at least 5 separate attempts at maximum dose before declaring treatment failure 2
• Common reasons for failure: Lack of sexual stimulation, medication taken with large meal, incorrect timing, excessive alcohol consumption 5

Safety Precautions

• Absolute contraindication: Never use with nitrates due to risk of dangerous, potentially fatal hypotension 2, 1
• Timing with nitrates: If emergency nitrate therapy is needed, at least 24 hours should have passed since taking sildenafil (though tadalafil's longer half-life of 17.5 hours requires even greater caution) 5, 6
• Cardiovascular assessment: Evaluate ability to perform moderate physical activity before prescribing; refer to cardiology if unable 2

Dose Adjustments for Special Populations

Renal Impairment (As-Needed Dosing)

• Creatinine clearance 30-50 mL/min: Start with 5 mg, maximum 10 mg once every 48 hours 1
• Creatinine clearance <30 mL/min or hemodialysis: Maximum 5 mg once every 72 hours 1

Hepatic Impairment

• Mild to moderate (Child-Pugh Class A or B): Do not exceed 10 mg once per day 1
• Severe (Child-Pugh Class C): Tadalafil is not recommended 1

Difficult-to-Treat Populations

• Men with diabetes and post-prostatectomy patients have more severe ED at baseline and may respond less robustly to PDE5 inhibitors 2
• For men with ED and testosterone deficiency, combining tadalafil with testosterone therapy may be more effective than tadalafil alone 2

Common Adverse Effects

• Most common: dyspepsia, headache, back pain, nasal congestion, and myalgia 2, 7
• Tadalafil has lower rates of flushing compared to other PDE5 inhibitors 2
• Serious adverse events occur in less than 2% of patients, with no significant difference compared to placebo 5
• No visual side effects have been noted with tadalafil, unlike sildenafil 8

Switching from Other PDE5 Inhibitors

For men with incomplete response to maximum-dose as-needed PDE5 inhibitor therapy, switching to tadalafil once-daily dosing (5 mg) can result in return to normal erectile function in 39-40% of patients compared to 12% with placebo. 9

Important Clinical Pearls

• Do not split tablets: The entire dose should be taken 1
• Titrate doses to find optimal balance between efficacy and side effects 2
• Periodic follow-up is recommended to evaluate efficacy, side effects, and any significant changes in health status or medications 5
• If inadequate response occurs, assess whether use was adequate before changing therapy, considering factors such as timing, sexual stimulation, and relationship dynamics 5