Alendronic Acid/Fosamax Weekly

Alendronic acid 70mg is the most widely prescribed bisphosphonate for osteoporosis in the UK. Its once-weekly dosing schedule is now the default formulation in the majority of clinical settings, recommended in NHS guidance and supported by a large body of real-world prescribing evidence. Alendronic Acid/Fosamax Weekly 70mg Tablets deliver a single oral dose of alendronate once every seven days for the treatment of osteoporosis in postmenopausal women and in men, and for the prevention of osteoporosis in postmenopausal women at risk of fracture.

The once-weekly regimen was introduced following published evidence that reducing dosing frequency from daily to weekly improved patient adherence to bisphosphonate therapy without any reduction in clinical efficacy. Adherence to long-term preventive medicines is a recognised challenge across all therapeutic areas; in osteoporosis, where the benefit of treatment is measured in fractures avoided over years, gaps in treatment can have lasting consequences. This medicine is a Prescription Only Medicine. A clinical consultation with a registered prescriber is the required first step before any supply.

Fosamax Once Weekly is the branded originator product containing alendronic acid 70mg as a film-coated tablet. Generic alendronic acid 70mg once-weekly tablets are bioequivalent alternatives that contain the same active ingredient at the same dose and are therapeutically interchangeable within the licensed indication. Both are referred to on this page as alendronic acid 70mg weekly.

Alendronic acid is a nitrogen-containing bisphosphonate. Within this class, individual medicines differ in their molecular structure, binding affinity to bone mineral, potency within the osteoclast, and their pharmacokinetic behaviour following absorption. Alendronate has been studied more extensively than any other bisphosphonate in large-scale, long-term clinical trials and has the most extensive real-world evidence base for fracture prevention in postmenopausal osteoporosis.

The 70mg once-weekly formulation is licensed in the UK for three distinct indications. It is licensed for the treatment of osteoporosis in postmenopausal women to reduce the risk of vertebral and hip fractures. It is also licensed for the prevention of osteoporosis in postmenopausal women at risk, and for the treatment of osteoporosis in men. The breadth of its licensed indications reflects the depth of clinical evidence that has accumulated across each of these patient populations over decades of use.

The weekly tablet was purposefully designed with an effervescent version (Binosto 70mg effervescent tablet) available as an alternative for patients who have difficulty swallowing conventional film-coated tablets, though that formulation is not the subject of this page.

Bone mineral density in an adult represents the cumulative product of years of bone remodelling – cycles of resorption and formation that renew approximately ten per cent of the adult skeleton each year. The rate at which bone turns over varies by site, with trabecular bone in the spine and femoral neck being metabolically more active than cortical bone in the shafts of long bones. This higher metabolic activity makes these sites more responsive to bisphosphonate therapy, and also more vulnerable to bone loss in osteoporosis.

Following oral ingestion on an empty stomach, approximately one per cent of the 70mg dose is absorbed from the small intestine – a figure that reflects the inherently low oral bioavailability of all bisphosphonates. Once in the circulation, alendronate is taken up rapidly by bone surfaces, concentrating at sites where bone remodelling is most active. It incorporates into bone mineral and remains there until osteoclasts attempt to resorb that section of bone.

The weekly 70mg dose, like the daily 10mg regimen, inhibits farnesyl pyrophosphate synthase within the osteoclast. This enzyme sits at a pivotal point in the mevalonate pathway, controlling the production of isoprenoid lipid molecules that osteoclasts require to maintain their internal cytoskeletal organisation and function. Without these lipids, osteoclasts cannot attach to bone surfaces effectively and lose their capacity to resorb mineral. The cell eventually undergoes apoptosis, and the local rate of bone resorption falls substantially.

Over time – typically measurable from six months onward – the reduced rate of bone resorption allows the balance between resorption and formation to shift. Bone mineral density increases at the lumbar spine, femoral neck, and total hip. This measurable increase in density corresponds to a clinically relevant reduction in the incidence of both vertebral and hip fractures in postmenopausal women, as established in the pivotal Fracture Intervention Trial and subsequent studies.

Select one day of the week as your alendronate day and take one 70mg tablet on that morning every week. The choice of day is yours to make, but once chosen, consistency matters. Many patients choose a day that anchors easily to another weekly activity – a regular appointment, a shopping routine, or simply the same day each week chosen for convenience.

Take the tablet on that chosen morning before anything else – before eating, before drinking anything other than plain tap water, and before taking any other oral medicine. The fasting window is not a preference; it is a pharmacokinetic requirement. Bisphosphonate absorption is acutely sensitive to the presence of food and other drinks in the stomach. Even small quantities of food, coffee, tea, milk, orange juice, or mineral water at the time of dosing substantially impair absorption. The only acceptable liquid for swallowing the tablet is plain tap water.

Use a full glass of water – at least 200ml – to swallow the tablet whole. Do not crush or chew the tablet. After taking it, remain fully upright: standing or sitting in a chair. Do not return to bed. Maintain this upright posture for a minimum of thirty minutes. The tablet should not be taken at bedtime under any circumstances.

The purpose of the thirty-minute upright period is mechanical: it ensures the tablet passes efficiently through the oesophagus into the stomach and does not linger against the oesophageal mucosa. Alendronate is capable of causing localised mucosal damage if it remains in contact with the oesophageal lining for a prolonged period. Correct technique – adequate water volume, upright posture, morning timing before food – makes this risk very low in practice.

After the thirty-minute window has passed, eat breakfast and take any other medicines or supplements at that point. Calcium supplements, antacids, iron preparations, and products containing magnesium or aluminium must not be taken within thirty minutes of alendronate; in practice, taking them with or after breakfast keeps them well separated. If you miss your weekly dose, take it on the morning of the following day and then return to your usual weekly schedule. Do not take two tablets within the same seven-day period.

Licensed Strength and Schedule

Alendronic Acid/Fosamax Weekly is available as a single 70mg tablet taken once every seven days. This is the only dose and schedule covered by this product page.

Why the Shift From Daily to Weekly

When alendronate was first widely prescribed in the UK, the standard formulation was a 10mg tablet taken every morning. This daily schedule required patients to observe the fasting and posture requirements seven mornings per week, every week of the year. Research into how patients actually took their prescribed bisphosphonates found that a significant proportion struggled to maintain this daily routine over the long term.

The development of the 70mg once-weekly tablet arose directly from this evidence. By compressing the weekly dose into a single larger tablet taken on one chosen morning, the treatment achieved two goals simultaneously: the total weekly exposure to alendronate remained identical to the daily regimen, and the number of mornings per week on which patients needed to observe the fasting and posture requirements reduced from seven to one.

Supplementation with Calcium and Vitamin D

Prescribers frequently advise patients on alendronate to take calcium and vitamin D supplements alongside their bisphosphonate therapy. Calcium provides the mineral substrate for new bone formation, and vitamin D is essential for calcium absorption from the gut. Both are needed for alendronate to produce its optimal effect on bone density. Any supplementation should be taken at a separate time from alendronate – ideally with or after a meal, to avoid any reduction in alendronate absorption.

Concentrating the weekly dose into a single 70mg tablet means that any gastrointestinal effects, if they occur, arise on one morning per week rather than every morning. For some patients this makes the weekly formulation meaningfully easier to tolerate than the daily 10mg tablet, as any discomfort is confined to the dosing day rather than recurring daily. The following information reflects the current UK Summary of Product Characteristics for alendronic acid 70mg.

Common Side Effects (may affect up to 1 in 10 people)

1. Abdominal pain, bloating, or discomfort
2. Nausea
3. Heartburn or acid reflux
4. Constipation or diarrhoea
5. Musculoskeletal pain, including pain in the bones, joints, or muscles
6. Headache

Uncommon Side Effects (may affect up to 1 in 100 people)

1. Oesophageal ulceration or erosion – most commonly associated with incorrect administration technique
2. Gastric or duodenal ulceration
3. Skin rash, itching, or redness
4. Transient flu-like symptoms following the first dose (acute phase reaction), including fever, muscle aches, and fatigue – these typically resolve within a few days and do not recur
5. Eye inflammation, including uveitis or episcleritis
6. Low blood calcium, particularly in patients with vitamin D deficiency

Rare and Serious Adverse Effects

The following adverse effects are rare but associated with long-term bisphosphonate use. Patients should be aware of them throughout the course of treatment.

1. Osteonecrosis of the jaw (ONJ): rare deterioration of jaw bone, most commonly triggered by invasive dental procedures in patients taking bisphosphonates. Inform your dentist that you are taking alendronate before any dental treatment that involves the jaw bone, including extractions, implants, and surgery. Good oral hygiene and regular dental check-ups are recommended.
2. Atypical femoral fractures: stress fractures at unusual locations in the shaft of the thigh bone, associated with prolonged bisphosphonate therapy. These often present first as a dull, aching pain in the thigh, hip, or groin. New or worsening pain of this nature should be reported to a prescriber promptly, without waiting for a scheduled review. Bilateral symptoms should also be investigated.
3. Severe or incapacitating musculoskeletal pain, which may resolve on stopping the medicine
4. Severe cutaneous reactions including Stevens-Johnson syndrome (very rare)

Three Licensed Patient Groups

The 70mg once-weekly formulation is licensed for a broader range of patients than some other bisphosphonate formulations in the catalogue. It is licensed for the treatment of osteoporosis in postmenopausal women to reduce the risk of both vertebral and hip fractures, for the prevention of osteoporosis in postmenopausal women at elevated fracture risk, and for the treatment of osteoporosis in men to reduce the risk of fractures.

This breadth of licensed indications means that both postmenopausal women and men presenting with a confirmed osteoporosis diagnosis or a significant fracture risk profile may be considered for this formulation. Prescribing decisions will be based on each individual's bone density measurements, fracture history, relevant comorbidities, concurrent medicines, and the clinical judgement of their prescriber.

Clinical Circumstances Where Alendronate May Not Be Appropriate

Alendronic acid 70mg weekly is not suitable for all patients. The following represent absolute contraindications.

1. Uncorrected hypocalcaemia at the time of starting treatment – calcium levels must be corrected before bisphosphonate therapy begins
2. Severe renal impairment with creatinine clearance below 35ml per minute
3. Oesophageal conditions that impair normal oesophageal emptying, such as stricture, achalasia, or other motility disorders
4. Inability to stand or sit upright for at least thirty minutes after taking the dose
5. Known hypersensitivity to alendronic acid or any excipient in the tablet

Active upper gastrointestinal conditions – including oesophagitis, Barrett's oesophagus, active gastric ulcer, or recent upper gastrointestinal surgery – should be disclosed to the prescriber. These may represent relative contraindications or require careful clinical evaluation before alendronate is initiated.

Alendronate is not licensed for children or adolescents and is not recommended during pregnancy or breastfeeding. Patients with a known history of atypical femoral fractures on previous bisphosphonate therapy should inform their prescriber, as the decision to continue or restart therapy requires individual clinical assessment.

Alendronic acid 70mg weekly is a Prescription Only Medicine. A clinical consultation is the first and mandatory step. The purpose of the consultation is to establish your individual clinical suitability for this medicine. A prescription is a possible outcome of the consultation, not a predetermined result. It will be issued only if the prescriber determines that alendronate 70mg weekly is clinically appropriate for you at this time.

During your consultation through Pharmacy Planet, a UK registered prescriber will review the information you provide about your diagnosis, bone density history, any fractures you have experienced, your current medicines, relevant medical conditions, and any previous experience with bisphosphonate therapy. This information informs the clinical decision about whether to prescribe.

For patients newly presenting with osteoporosis, the prescriber will assess whether the diagnosis is supported by appropriate investigation – typically a DEXA scan result or a validated fracture risk score such as FRAX or QFracture. For patients transferring an existing prescription for ongoing supply, the prescriber will confirm that continued treatment remains clinically appropriate and that no new circumstances have arisen that would warrant a change in treatment.

If additional clinical information is needed before a prescribing decision can be made, you will be informed clearly and guided on how to provide it. Our pharmacy team remains available throughout the process to answer questions and to assist with any aspect of your consultation or ongoing supply.

Store alendronic acid 70mg tablets at room temperature, below 25 degrees Celsius. Keep the tablets in their original blister packaging. Blisters protect individual tablets from moisture and light between doses; once-weekly dosing means that each strip covers many weeks, making appropriate storage over that longer period important.

Mark your chosen dosing day on a calendar, on your phone, or using a pill organiser with a weekly compartment. Because the tablet is taken only once per week, it is easy to lose track of whether a dose has been taken. Establishing a reliable visual or alert reminder from the outset reduces the likelihood of missed or accidental double doses.

Check the expiry date on each blister strip before taking a dose. The date printed on the packaging refers to the last day of the month shown. Do not take expired tablets. Return any unused or out-of-date tablets to a pharmacy for safe and environmentally responsible disposal. Medicines should not enter household waste bins or drains.

All seven medicines listed below are oral tablets or capsules prescribed for osteoporosis, the same therapeutic category and the same form factor, making direct comparison appropriate. They differ in their active ingredient, dosing frequency, licensed indication, and mechanism of action.

The table below compares commonly prescribed oral bisphosphonate treatments available through Pharmacy Planet's osteoporosis service. Products are listed in order of dosing frequency, from daily to monthly, so you can quickly identify how each medicine fits into a patient's routine.

Important: This comparison is for general information only and does not replace medical advice. A prescriber will decide which treatment is suitable for you following an online consultation. All medicines listed are Prescription Only Medicines (POMs). Suitability depends on individual clinical circumstances including diagnosis, renal function, medical history, and concurrent medicines.

Pharmacy Planet is a GPhC-registered online pharmacy that provides safe, regulated, and clinically governed prescription services to patients across the UK. Our dispensing processes operate under the supervision of a qualified superintendent pharmacist, and every prescription we fulfil is checked by a qualified pharmacist before dispatch.

Alendronic acid 70mg weekly is one of the most commonly prescribed medicines in the UK for long-term osteoporosis management. For patients who have been on this treatment for years, reliable repeat prescribing is as important as the medicine itself. Our consultation and dispensing service is designed to give established patients a straightforward, clinically safe route to their ongoing prescription without disruption to their treatment continuity.

Our pharmacy team is available to answer clinical questions about your alendronate treatment, to clarify administration guidance, and to liaise with the prescribing team on your behalf where needed. Patient safety, accurate dispensing, and consistent access to treatment are the principles that guide everything we do.

1. electronic Medicines Compendium (emc). Fosamax Once Weekly 70mg Tablets / Alendronic Acid 70mg Tablets – Summary of Product Characteristics. www.medicines.org.uk/emc. Accessed June 2026.
2. British National Formulary (BNF). Alendronic acid. bnf.nice.org.uk/drugs/alendronic-acid. Accessed June 2026.
3. NHS. Alendronic acid. www.nhs.uk/medicines/alendronic-acid. Accessed June 2026.
4. National Osteoporosis Guideline Group (NOGG). Clinical Guideline for the Prevention and Treatment of Osteoporosis. www.nogg.org.uk. Accessed June 2026.
5. Cramer JA, et al. Medication compliance and persistence: terminology and definitions. Value in Health. 2008;11(1):44-47. Cited for adherence terminology in bisphosphonate prescribing literature.
6. Black DM, et al. Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures (Fracture Intervention Trial). Lancet. 1996;348(9041):1535-1541.